Air / vacuum relief valves with improved air flow vectoring profiles

Abstract

The present disclosure provides vacuum relief valves having improved air flow performance characteristics for use in connection with pipelines, such as sewer pipelines.

Description

[0001] AIR / VACUUM RELIEF VALVES WITH IMPROVED AIR FLOW VECTORING PROFILES

[0002] FIELD

[0003] The present disclosure provides valves, such as vacuum relief valves, for use with water and waste-water pipelines.

[0004] BACKGROUND

[0005] Vacuum relief valves are installed along water and waste-water pipelines principally to allow air to enter the pipeline during pipeline draining or negative pressure events caused by pressure surges and to protect the pipeline from collapse and, wherein the addition of air provides a pneumatic cushion, which if appropriately managed can be used to control potential water hammer induced by the rapid rejoining of water columns often caused by pressure surges that often follow sudden changes in pumping rates.

[0006] Air release valves are installed along water and waste-water pipelines principally to allow removal of pressurized gas pockets that tend to accumulate at the highpoints along the pipeline, otherwise these accumulations increase the energy required to pump the fluids. The air can also be expelled during pipeline filling operations (at low pressure) and during surge events where water column / s are rejoining, in which case these air release valves can be fitted with anti-surge devices to limit the closing velocity of the water columns to approximately 1 ft / sec, which would be expected to generate ~50 psi pressure wave (water hammer effect). This surge pressure wave is roughly proportional to the closing velocity, and if not controlled can cause damage to the CARV and the pipeline, either directly or when reflected wave fronts meet resulting in pressure amplification.

[0007] Combination air / vacuum release valves (CARVs) are devices that incorporate all the function described above into one piece of equipment. For the purposes of this discussion, reference to a CARV includes a device with any or all combinations of the above functions.

[0008] Pipelines are often installed underground for a variety of reasons and frequently follow underneath a roadway, which means the CARVs are similarly located. To facilitate access the CARVs may be installed in vaults (e.g., of concrete, brick, fiberglass, resin, reinforced plastic, etc.), with access controlled by a heavy metal manhole lid, which are commonly seen dotted along most city and suburban roads and may be shared with other utilities, such as natural-gas and electricity. Because the atmosphere inside these vaults can be hazardous due to the presence of methane, or absence of sufficient oxygen concentrations, they are subject to ‘confined entry' safety procedures, and require emergency extraction mechanisms for entry personnel and use of protective suits and gloves, etc. In many situations, the opening of a manhole located on a public road creates further safety and permission issues, making the inspection of CARVs a time consuming and costly event.

[0009] Vacuum relief valves (including CARVs) commonly in use today do not allow for efficient air intake when a vacuum forms in a pipeline to which the vacuum relief valve is connected. For a given air relief valve installation, the valve's air intake capacity is generally the primary variable that determines the size of the specified air relief valve. However, the present inventor has discovered that Mach flow choking effects emerge at certain locations along a CARV when a vacuum exceeding about -4 psig forms in an associated pipeline. This Mach flow choking effect significantly reduces the rate at which air entering the CARV can flow into an associated pipeline, which in turn increases the risk of catastrophic pipe failure even when the CARV is in fully functional order. Surprisingly, the present inventors have found that these Mach choking effects inhibit flow less when concentrated near the junction of a CARV and the associated pipeline. The present disclosure provides air relief valves (e.g., CARVs) including air flow vectoring profiles that substantially reduce the Mach choking effects in air relief valves such as CARVs, especially at or near the junction of a CARV and an associated pipeline (e.g., exhaust Pipe).

[0010] SUMMARY

[0011] In one embodiment, the present disclosure provides a base flange for a vacuum relief valve, wherein the base flange comprises an exit port having a filleted cross-sectional profile, wherein the filleted cross-sectional profile is a truncated (e.g., not a full quarter-round) circular radial profile.

[0012] In another embodiment, the present disclosure provides a base flange for a vacuum relief valve comprising an exit port having an asymmetric circular radial filleted cross-sectional profile, wherein the asymmetric circular radial filleted cross-sectional profile that is tangential to a top surface of the base flange; and is not tangential to an inner side wall of an exhaust pipe coupled to the base flange.

[0013] In still other embodiments, the present disclosure provides a vacuum relief valve including a base flange comprising an exit port having a truncated circular filleted cross- sectional profile or a truncated non-circular or non-truncated non-circular filleted cross-sectional profile.

[0014] In still other embodiments, the present disclosure provides a vacuum relief valve comprising a base flange including an exit port having an asymmetric circular radial filleted cross-sectional profile, wherein the asymmetric circular radial filleted cross-sectional profile that is tangential to a top surface of the base flange; and is not tangential to an inner side wall of an exhaust pipe coupled to the base flange.

[0015] In still other embodiments, the present disclosure provides a base flange for a vacuum relief valve comprising an exit port having an elliptical filleted cross-sectional profile.

[0016] In still other embodiments, the present disclosure provides a vacuum relief valve comprising an exit port configured to enable air to enter an exhaust pipe coupled to the vacuum relief valve, wherein the air entering the exhaust pipe defines a column air, and wherein the column of air occupies all or substantially all of an inside volume of the exhaust pipe.

[0017] In still other embodiments, the present disclosure provides a method of improving vacuum relief performance of a waste line, the method comprising: decoupling a preexisting vacuum relief valve from an exhaust pipe, wherein the preexisting vacuum relief valve includes an exit port defined by a base flange that includes a non-f illeted cross-sectional profile; and coupling a vacuum relief valve consistent with the present disclosure to the exhaust pipe.

[0018] These and other embodiments are described in more detail herein below.

[0019] BRIEF DESCRIPTION OF THE FIGURES

[0020] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0021] FIG. 19 shows a cutaway view of a vacuum relief valve including a base flange featuring an exit port having a non-f illeted cross-sectional profile, the base flange being consistent with the prior art.

[0022] FIG. 1 shows a cutaway view of a vacuum relief valve including a base flange featuring an exit port having a non-f illeted cross-sectional profile, the base flange being consistent with the prior art. FIG. 2 shows a cutaway view of a vacuum relief valve including a base flange featuring an exit port having a filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0023] FIG. 3 shows a cutaway view of a vacuum relief valve including a base flange featuring an exit port having a filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0024] FIG. 4 shows a cutaway view of a vacuum relief valve including a base flange featuring an exit port having a filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0025] FIG. 5 shows a cross-sectional view of a portion of a base flange featuring an exit port having an asymmetrical truncated circular radial (filleted) cross-sectional profile consistent with one embodiment of the present disclosure. Airflow through the CARV when a vacuum is applied from the pipeline 310 is represented by the curved arrow (A).

[0026] FIG. 6 shows a cross-sectional view of the portion of the base flange of FIG. 6 compared to a symmetrical non-truncated circular radial (filleted) profile ( — ■ — ).

[0027] FIG. 7 shows a cross-sectional view of a portion of a base flange featuring an exit port having an asymmetrical truncated elliptical (filleted) cross-sectional profile consistent with another embodiment of the present disclosure. Airflow through the CARV when a vacuum is applied from the pipeline 310 is represented by the curved arrow (A).

[0028] FIG. 8 shows a cross-sectional view of the portion of the base flange of FIG. 8 compared to a symmetrical non-truncated elliptical (filleted) profile ( — ■ — ).

[0029] FIG. 9 shows graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having a filleted cross-sectional profile consistent with one embodiment of the present disclosure and showing an overlay of square computational cells used in the in silico study.

[0030] FIG. 10 shows a portion of the graphical results of in silico airflow modeling for a prior art vacuum relief valve including a base flange featuring an exit port having a symmetrical quarterround fillet.

[0031] FIG. 1 1 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve (using the same test conditions used in FIG.10) including a base flange featuring an exit port having a truncated circular radial filleted cross-sectional profile to achieve full crosssection flow in the exhaust pipe consistent with one embodiment of the present disclosure.

[0032] FIG. 12 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring a 1 mm (~ 3% thickness) radiused fillet (in practice considered as non-filleted’) cross-sectional profile consistent with the prior art.

[0033] FIG. 13 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having a non-truncated circular radial filleted cross-sectional profile consistent with prior art.

[0034] FIG. 14 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having an asymmetrical truncated circular radial filleted cross-sectional profile consistent with one embodiment of the present disclosure.

[0035] FIG. 15 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having an asymmetrical truncated circular radial filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0036] FIG. 16 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having an asymmetrical elliptical filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0037] FIG. 17 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having an asymmetrical truncated elliptical filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0038] FIG. 18 shows a portion of the graphical results of in silico airflow modeling for a vacuum relief valve including a base flange featuring an exit port having an asymmetrical truncated elliptical filleted cross-sectional profile consistent with another embodiment of the present disclosure.

[0039] FIG. 19 shows a vacuum relief valve or CARV including a non-filleted (right angle) profile of its air exit orifice, consistent with the prior art and as disclosed in U.S. Patent No. 5,51 1 ,577. DETAILED DESCRIPTION

[0040] Referring generally to FIGS. 1 -18, the present disclosure provides vacuum relief valves (e.g., CARVs) featuring significantly improved vacuum relief performance characteristics. The improvements observed over prior art vacuum relief valve designs were unexpected, especially in the magnitude of increased air flow under a wide range of applied vacuum intensities.

[0041] Vacuum relief valves have traditionally included a base flange for mounting the valve to a pipeline that features a non-f illeted air exit orifice. One example is the vacuum relief valve (a CARV in this case) disclosed in U.S. Patent No. 5,511 ,577. As shown in FIG. 19, the CARVs disclosed in the ‘577 Patent include only non-f illeted (right angle) profiles of the air exit orifice (reference number 20) in cross-section.

[0042] The air intake orifice (reference number 20) of the ‘577 Patent also features non-filleted (right angle) cross-sectional profile, on both its leading (external) edge and the trailing (internal) edge.

[0043] Our testing found CARVs of this design to suffer from a number of inefficiencies. Most notably, air flow through CARVs of this type tend to essentially plateau at sub-optimal airflow rates. Without wishing to be bound by theory, we observed through fluid dynamics modeling that air flowing through a CARV similar to that shown in Figure 3 of the ‘577 Patent induces significant vena contracta effects just below the base flange orifice, with a significant majority of the pipe’s inner cross-sectional area being virtually unused.

[0044] One example of this airflow testing observation is shown representatively in FIG. 12. Those data clearly illustrate that the inner diameter of the exhaust pipe 300 is significantly larger than the column of air flowing therethrough, resulting in unused void spaces V along the inner side wall 310 of the exhaust pipe 300. The net effect of these void spaces V is a choking of the vacuum relief valve 10 — the effective diameter of the exhaust pipe 300 being significantly smaller than the nominal diameter of the exhaust pipe 300. This narrowing of fluids flowing through a circular port is called Vena Contracta. Accordingly, vacuum relief valves 10 of this type must be larger and coupled to larger sized (e.g., inside diameter 315) exhaust pipes 300 to provide desired performance. Insufficient vacuum relief capacity of a CARV can lead to catastrophic failure of the main pipeline.

[0045] Believing that the observed vena contracta region may be acting as a governor, limiting the air flow potential of a CARV, we prepared and modeled CARVs 10 comprising base flanges 200 including exit ports 210 surrounded by filleted and comparative non-filleted base flange rim profiles 220 such as those shown in FIGS. 1 -18. The CARVs 10 included an air intake manifold 400 that, in response to vacuum applied in or below the CARV 10, allowed air to enter an interior chamber 510 of the body 500 of the CARV 10. The CARVs 10 further included a series of floats 600 that open and close the CARV to gas efflux or air intake in response to rising and falling liquid levels within the pipeline 310.

[0046] Non-filleted base flanges 200 including exit ports 210 surrounded by a base flange rim profile 220 that is not filleted performed poorly in our tests and in silica models. For example, the CARV 10 shown in FIG. 1 included a non-filleted base flange rim profile 220 including only a 1 mm radius rounded corner profile to simulate a non-filleted profiles produced by methods common in the industry. FIG. 12 shows the results of one such in silica test based on a -5.08 psig vacuum applied from the pipeline 310. Large void areas V are present along the inner side wall 320 of the exhaust pipe 300 indicating significant choking of the CARV 10. The air column itself reached maximum speeds of about Mach 0.8 (about 614 mph / 988 kph) at the core, with significantly slower speeds (about Mach 0.3) adjacent the void area V.

[0047] Circular Radial Base Flange Profiles

[0048] Referring now generally to FIGS. 3, 5-6, and 13-15, the present disclosure further provides base flanges 200 and CARVs 10 including base flanges 200 that include a circular base flange profile 220 surrounding an exit port 210.

[0049] Some efficiency gains are observed when the non-filleted profile of FIGS. 1 and 12 is replaced by a circular profile 220 having a radius r0substantially equal to the thickness 290 of the base flange 220. Such fully-filleted circular radial profiles 220 are sometimes referred to as quarter-round profiles, and are consistent with the representative circular radial profile shown in FIG. 5 where y is 90° or about 90°. The radius r of these full fillets is equal to or substantially equal to the thickness 290 of the base flange 200; the focus 230 of the corresponding circle 240 is colinear or substantially colinear with the bottom surface of the base flange 200 and is colinear or substantially colinear with the intersection between the top surface 250 of the base flange 200 and the filleted profile 220. The profile 220 of these full fillets is tangent to the top surface 250 of the base flange 200 (i.e. , cp is 0°) and also tangent to the inside wall 320 of the associated exhaust port 300 (i.e., p is 0°). FIG. 6 shows a fully-filleted circular radial profile in dash-dot lines ( — ■ — ) with a radius r0that is equal to the thickness 290 of the base flange 200. The focus 230' of this fully-filleted circular radial profile is colinear with the interface of the base flange 200 and the exhaust pipe 300, and colinear with the intersection of the filleted profile and the top surface 250 of the base flange 200. As a result, fully-filleted circular radial profiles of this type are also symmetrical.

[0050] Our testing of fully-filleted profiles 220 confirmed some gains in efficiencies, but indicated that significant choking of the CARV 10 remained present. For example, FIGS. 10 and 14 show the results of an in silico airflow model of a CARV 10 including a base flange 200 having a fully-filleted quarter-round circular radial profile 220 (both equal to 28.58 mm) when a vacuum of -5.08 psig is applied from the pipeline 310. Significant voids V remain present along the inner side wall 310 of the exhaust pipe 300, and maximum airflow speeds are relatively slow. Only one small region of airflow at Mach 1 was observed located in the exit port 210 immediately proximal to the filleted profile 220. Compared to a non-filleted base flange profile 220 such as those consistent with FIGS. 1 and 12, fully-filleted profiles 220 offer improved airflow rates of only about 20%.

[0051] Referring now to FIGS. 5-6, 1 1 , and 14, the present disclosure provides base flanges 200 including an exit port 210 surrounded by a circular radial filleted profile 220. The circular radial filleted profile 220 may in some embodiments have a radius rthat is greater than the thickness 290 of the base flange 200. In the embodiment specifically illustrated in FIGS. 5-6, for example, the radius r is greater than the thickness 290 of the base flange.

[0052] Circular radial filleted profiles 220 consistent with the present disclosure may be symmetrical or asymmetrical. A circular radial filleted profile 220 is symmetrical when the angle cp formed between the top surface 250 of the base flange 200 and the tangent line of the circle 240 at the point 260 where the profile 220 and the top surface 250 intersect is equal to the angle p formed between the inner side wall 310 of the exhaust pipe 300 and the tangent line of the circle 240 at the point where the profile 220 and the inner side wall 310 intersect. In embodiments where the radius rof the circle 240 is greater than the thickness 290 of the base flange 200 (i.e., when y is not equal to zero), the profile 220 is symmetrical when angle a is equal to angle / 3 (and therefore when angle <p is equal to angle p).

[0053] In contrast, a circular radial filleted profile 220 is asymmetrical when the angle cp formed between the top surface 250 of the base flange 200 and the tangent line of the circle 240 at the point 260 where the profile 220 and the top surface 250 intersect is not equal to the angle p formed between the inner side wall 310 of the exhaust pipe 300 and the tangent line of the circle 240 at the point where the profile 220 and the inner side wall 310 intersect. In embodiments where the radius rof the circle 240 is greater than the thickness 290 of the base flange 200 (i.e., when is not equal to zero), the profile 220 is asymmetrical when angle a is not equal to angle / 3 (and therefore when angle (p is not equal to angle p).

[0054] FIGS. 11 and 14 show results of in silica airflow models of a CARV 10 including a base flange 200 having a circular radial filleted profile 220 with a radius r that was about 18% greater (about 33.72 mm) than the thickness 290 of the base flange 200 (about 28.58 mm). In this model, the focus 230 of the circle was positioned such that the profile 220 was tangential to the top surface 250 of the base flange (i.e., a was 0° and <p was 0°) and such that the profile 220 was not tangential to the inner side wall 310 of the exhaust pipe 300 (i.e., / 3 was about 16.4° and p was about 16.4°).

[0055] The model included vacuum application of -5.08 psig in the pipeline 310. Unlike the airflow model results for non-filleted and fully-filleted (quarter-round) profiles, airflow into the exhaust pipe 300 for this asymmetric circular radial filleted profile 220 exhibited no vena contracta type behavior — no obvious void areas V along the inner side wall 310 of the exhaust pipe 300 were observed. Airflow speeds reached Mach 1 along the bottom portion of the filleted profile 220 proximal to the intersection of the base flange 200 and the exhaust pipe 300. Airflow speed along the inner side wall 310 of the exhaust pipe 300 were observed to exceed 300 mph — noticeably higher than observed along the inner side wall 310 when the base flange 200 included non-filleted and fully-filleted profiles 220.

[0056] In some embodiments, base flanges and CARVs incorporating base flanges consistent with the present disclosure advantageously feature flow capacities (e.g., flow capacities in an associated exhaust pipe) that are significantly higher than possible via comparable base flanges or the prior art and CARVs that incorporate same. Without wishing to be bound by theory, the inventor presently believes that improving airflow closely proximal to the walls of the exhaust pipe at a vacuum condition or modeled vacuum condition of -5.08 psig enables or translates to a significantly increased air flow capacity at more extreme vacuum conditions before separation of the airflow from the wall of the exhaut pipe ultimately occurs and results in a flow choking effect.

[0057] FIG. 15 shows results of an in silico airflow model of a CARV 10 including a base flange 200 having a circular radial filleted profile 220 with a radius rthat was about 18% greater (about 33.72 mm) than the thickness 290 of the base flange 200 (about 28.58 mm). In this model, the focus 230 of the circle was positioned such that the profile 220 was not tangential to the top surface 250 of the base flange or to the inner side wall 310 of the exhaust pipe 300. The offset or truncation of this circular radial profile 220 was asymmetric: the focus 230 of the circle 240 corresponding to the profile 220 was positioned such that angle jB was about twice that of angle a (i.e., a was about 5.5° while / 3 was about 10.9°, resulting in a base tangent angle p of about 6°).

[0058] This CARV 10 also performed significantly better than a comparable CARV including a non-filleted or fully-filleted base flange 200. As shown in FIG. 15, no voids V along the inner side wall 310 of the exhaust pipe 300 were observed, and air speed along the inner side wall 310 were quite high. The region of Mach 1 airflow was slightly larger for this CARV than the CARV including the semi-tangential circular radial profile 220 described above and shown in FIGS. 11 and 14.

[0059] In some embodiments, the radius r of a circular radial filleted profile 220 is at least about 5% greater than the thickness 290 of the base flange 220. In some embodiments, the radius rof a circular radial filleted profile 220 is at least about 10% greater than the thickness 290 of the base flange 220. In some embodiments, the radius rof a circular radial filleted profile 220 is at least about 15% greater than the thickness 290 of the base flange 220. In some embodiments, the radius r of a circular radial filleted profile 220 is at least about 20% greater than the thickness 290 of the base flange 220. In some embodiments, the radius r of a circular radial filleted profile 220 is at least about 25% greater than the thickness 290 of the base flange 220. In some embodiments, the radius rof a circular radial filleted profile 220 is about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 1 1%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 21%, about 22%, about 23%, about 24%, or about 25% greater than the thickness 290 of the base flange 220.

[0060] Non-Circular Base Flange Profiles

[0061] Referring now generally to FIGS. 3-4, 7-8, and 16-18, the present disclosure further provides base flanges 200 and CARVs 10 including base flanges 200 that include a non-circular base flange profile 220 surrounding an exit port 210. For example and without limitation, the non-circular base flange profile 220 in such embodiments may include a simple curve including a portion of an elliptical profile, a portion of an oval profile, or a portion of a parabolic curve; or a compound curve including two curves each independently selected from the group consisting of: elliptical, oval, and parabolic.

[0062] Referring now to FIGS. 7-8 and 16-18, the non-circular base flange profile 220 may in some embodiments include a simple curve that is a portion of an ellipsis 240. The profile 220 may be fully-filleted (e.g., non-truncated) in some embodiments. In such embodiments, the nontruncated elliptical profile has a geometric center 230' positioned such that the major axis 242' of the ellipsis 240 is colinear with the intersection point 260 between the filleted profile 220 and the top surface 250 of the base flange 200, and the minor axis 244' is colinear with the intersection of the base flange 200 and the exhaust pipe 300. In such embodiments, the filleted profile 220 is tangential to both the top surface 250 of the base flange 200 and to the inner side wall 310 of the exhaust pipe 300.

[0063] In other embodiments, the profile 220 is truncated. In some such embodiments, the profile 220 is truncated such that the ellipsis 240 is tangential to the top surface 250 of the base flange 200, but not tangential to the inner side wall 310 of the exhaust pipe 300. In other embodiments, the profile 220 is truncated such that the ellipsis 240 is not tangential to the top surface 250 of the base flange 200, but is tangential to the inner side wall 310 of the exhaust pipe 300. In still other embodiments, the profile 220 is truncated such that the ellipsis 240 is not tangential to the top surface 250 of the base flange 200 or to the inner side wall 310 of the exhaust pipe 300.

[0064] One example of an elliptical filleted profile 220 that is not tangential to either the top surface 250 of the base flange 200 or to the inner side wall 310 of the exhaust pipe 300 is shown representatively in FIG. 8. In such embodiments, the geometric center 230 of the ellipsis 240 is offset from the geometric center 230' of an ellipsis 240' corresponding to a comparable fully-filleted elliptical profile ( — ■ — ) both laterally and longitudinally. In this particular illustrated example, the magnitude of the longitudinal offset is greater than the magnitude of the lateral offset, resulting in a truncated elliptical profile 220 that is asymmetric.

[0065] In silica testing results of three CARVs 10 including base flanges 200 featuring elliptical filleted profiles 220 surrounding the exit port 210 are shown in FIGS. 16-18. The elliptical filleted profiles 220 of the CARVs 10 tested in FIGS. 16-18 were each offset such that the profile 220 was truncated to be about 6° out of tangent from the inner side wall 310 of the exhaust pipe 300 (p was about 6°).

[0066] All three elliptical profiles 220 performed well, with no substantial void regions V along the inner side wall 310 of the exhaust pipe 300. The largest of the elliptical profiles 220, shown in FIG. 18, began to display some areas of low airflow L along the inner side wall 310 proximal to the junction between the base flange 200 and the exhaust pipe 300. All three CARVs 10 achieved Mach 1 airflow speeds immediately adjacent the elliptical profiles 220, with the location of the maximum airflow speed region migrating towards the junction with the exhaust pipe 300 as the size of the ellipsis 240 was increased.

[0067] Unless otherwise indicated, in silico airflow testing was performed using SolidWorks (2012) Computational Fluid Dynamics (CFD) software benchmarked to actual physical flow testing of a range of CARVs having various sizes and similar geometries as CARVs 10 illustrated in FIGS. 1-4. The internal flow regions 510, 210, 310 of the CARVs 10 were divided into about 6 million computational cells shown representatively in FIG. 9. The size of each cell was determined by the CFD software based on calculated differences between adjacent cells and absolute airflow values in each cell. CARVs 10 used in these in silico models were 8-inch size. The vacuum applied from the pipeline 310 was -5.08 psig unless otherwise stated. These in silico models did not consider change of state effects on moisture that could be present in the airflow from rapid temperature changes (e.g., freezing) in the flowing air; modeling assumed dry air (i.e., 0% humidity) entering the CARV 10 at 14.7 psia and 70°F.

[0068] Base Flanges

[0069] The present disclosure provides base flanges 200 configured to be incorporated into or mate with the body 500 of a CARV 10, for example at the end of the CARV 10 adjacent to an exhaust pipe 300. The base flange 200 defines an exit port 210 through which air A passes from the cavity 510 of the CARV 10 into an adjacent exhaust pipe 300. In some embodiments, the base flange 200 has an annular ring shape. The exit port 210 may have an inner diameter 215 (e.g., minimum inner diameter) that is the same as or substantially the same as the inner diameter 315 of the exhaust pipe 300.

[0070] In some embodiments, the present disclosure provides a base flange 200 for a vacuum relief valve 10, wherein the base flange 200 comprises an exit port 210 having a filleted cross- sectional profile 220. In some embodiments, the filleted cross-sectional profile 220 comprises a truncated circular radial profile 220. In some embodiments, the truncated circular radial profile 220 has a radius / "greater than the thickness 290 of the base flange 200. In some embodiments, the radius r is at least 10% greater than the thickness 290 of the base flange 200. In some embodiments, the radius r is at least 15% greater than the thickness 290 of the base flange 200. In some embodiments, the radius is at least 20% greater than the thickness 290 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is tangential to a top surface 250 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to a top surface 250 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to a top surface 250 of the base flange 250 and is not tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is defined at least in part by a focal point 230 that is offset from a comparative focal point 230' of a non-truncated circular radial profile 240' such that the truncated circular radial profile 220 is offset from tangent relative to the top surface 250 of the base flange 200 by a first angle a and is offset from tangent relative to the inner side wall of the exhaust pipe by a second angle / 3. In some embodiments, the first angle a is about 1° to about 20°, for example about 1 °, about 2°, about 3°, about 4°, about 5°, about 6°, about 7°, about 8°, about 9°, about 10°, about 11 °, about 12°, about 13°, about 14°, about 15°, about 16°, about 17°, about 18°, about 19°, about 20°. In some embodiments, the second angle / 3 is about 1 ° to about 20°, for example about 1 °, about 2°, about 3°, about 4°, about 5°, about 6°, about 7°, about 8°, about 9°, about 10°, about 11 °, about 12°, about 13°, about 14°, about 15°, about 16°, about 17°, about 18°, about 19°, about 20°.

[0071] In some embodiments, the present disclosure provides a base flange 200 for a vacuum relief valve 10 comprising an exit port 210 surrounded by an asymmetric circular radial filleted cross-sectional profile 220, wherein the asymmetric circular radial filleted cross-sectional profile 220: is tangential to a top surface 250 of the base flange 200; and is not tangential to an inner side wall 310 of an exhaust pipe 300 coupled to the base flange 200. In some embodiments, the asymmetric circular radial filleted cross-sectional profile 220 has a radius r that is about 10% to about 25% greater than the thickness 290 of the base flange 200, for example about 10% greater than, about 1 1% greater than, about 12% greater than, about 13% greater than, about 14% greater than, about 15% greater than, about 16% greater than, about 17% greater than, about 18% greater than, about 19% greater than, about 20% greater than, about 21% greater than, about 22% greater than, about 23% greater than, about 24% greater than, or about 25% greater than the thickness 290 of the base flange 200.

[0072] In some embodiments, the filleted cross-sectional profile 220 comprises a non-circular elliptical profile including a major axis 242 and a minor axis 244 that intersect at a geometrical center 230. In some embodiments, the non-circular elliptical profile 220 is truncated and defined at least in part by a geometrical center 230 disposed offset from a geometrical center 230' of a comparative ellipse 240 defined by: a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200; and a comparative minor axis 244’ that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the geometrical center 230 of the noncircular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240’ in one dimension such that the major axis 242 is non-tangential to the top surface 250 of the base flange 200 while the minor axis 244 is tangential to the inner side wall 310 of the exhaust pipe 300. In some embodiments, the geometrical center 230 of the non-circular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240' in one dimension such that the minor axis 244 is non-tangential to the inner side wall 310 of the exhaust pipe 300 while the major axis 242 is tangential to the top surface 250 of the base flange 200. In some embodiments, the geometrical center 230 of the non-circular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240' in two dimensions such that the major axis 242 is non-tangential to the top surface 250 of the base flange 220 and the minor axis 244 is non-tangential to the inner side wall 310 of the exhaust pipe 300. In some embodiments, the major axis 242 of the non-circular elliptical profile 220 is greater than a comparative major axis 242' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the minor axis 244 of the non-circular elliptical profile 220 is greater than a comparative minor axis 244' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the major axis 242 and the minor axis 244 of the non-circular elliptical profile 220 are each greater than a comparative major axis 242' and a comparative minor axis 244' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200.

[0073] In some embodiments, the present disclosure provides a base flange 200 for a vacuum relief valve 10 comprising an exit port 210 having an elliptical filleted cross-sectional profile 220. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to a top surface 250 of the base flange 200. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to an inner side wall 310 of an exhaust pipe 300 configured to be coupled to the base flange 200. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to a top surface 250 of the base flange 200 and is tangential to an inner side wall 310 of an exhaust pipe 300 configured to be coupled to the base flange 200.

[0074] Vacuum Valves (CARVs)

[0075] The present disclosure provides vacuum relief valves (CARVs) 10 configured to relieve gas pressure or vacuum forces within an associated pipeline 310. In general, vacuum relief valves 10 of the present disclosure include a body portion 500 disposed between an air inlet portion 400 and an exit port 210 through which air A flows into or out of an associated pipeline 310. In some embodiments, the vacuum relief valve 10 includes one or more floats 600 configured to seal the air inlet portion 400, for example when liquid levels rise from the pipeline 310 into the vacuum relief valve 10, and / or to seal the exit port 210 in the absence of a positive pressure gradient between the pipeline 310 and the atmosphere surrounding the vacuum relief valve 10.

[0076] The exit port 210 is surrounded by (e.g., defined by) a base flange 200 that may be incorporated into the vacuum relief valve 10 (e.g., by permanently affixing the base flange 200 to the body portion 500) or may be added to a preexisting vacuum relief valve that includes an outlet orifice that is too large for the inside diameter 315 of an associated exhaust pipe 300 or that does not include an outlet orifice configured to align with the inside diameter 315 of an associated exhaust pipe 300. For example and without limitation, the exit port 210 may be surrounded by a base flange 200 that is configured to be inserted as an adapter or coupling linkage between a vacuum relief valve and an exhaust pipe 300.

[0077] The base flange 200 surrounds the exit port 210 and includes a filleted cross-sectional profile 220 consistent with any embodiment of the present disclosure. In some embodiments, the filleted cross-sectional profile 220 comprises a truncated circular radial profile 220. In some embodiments, the truncated circular radial profile 220 has a radius r greater than the thickness 290 of the base flange 200. In some embodiments, the radius r is at least 10% greater than the thickness 290 of the base flange 200. In some embodiments, the radius r is at least 15% greater than the thickness 290 of the base flange 200. In some embodiments, the radius is at least 20% greater than the thickness 290 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is tangential to a top surface 250 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to a top surface 250 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is not tangential to a top surface 250 of the base flange 250 and is not tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the truncated circular radial profile 220 is defined at least in part by a focal point 230 that is offset from a comparative focal point 230' of a non-truncated circular radial profile 240' such that the truncated circular radial profile 220 is offset from tangent relative to the top surface 250 of the base flange 200 by a first angle a and is offset from tangent relative to the inner side wall of the exhaust pipe by a second angle / 3. In some embodiments, the first angle a is about 1° to about 20°, for example about 1 °, about 2°, about 3°, about 4°, about 5°, about 6°, about 7°, about 8°, about 9°, about 10°, about 11 °, about 12°, about 13°, about 14°, about 15°, about 16°, about 17°, about 18°, about 19°, about 20°. In some embodiments, the second angle / 3 is about 1 ° to about 20°, for example about 1 °, about 2°, about 3°, about 4°, about 5°, about 6°, about 7°, about 8°, about 9°, about 10°, about 1 1 °, about 12°, about 13°, about 14°, about 15°, about 16°, about 17°, about 18°, about 19°, about 20°.

[0078] In some embodiments, the filleted cross-sectional profile 220 comprises an asymmetric circular radial filleted cross-sectional profile 220, wherein the asymmetric circular radial filleted cross-sectional profile 220: is tangential to a top surface 250 of the base flange 200; and is not tangential to an inner side wall 310 of an exhaust pipe 300 coupled to the base flange 200. In some embodiments, the asymmetric circular radial filleted cross-sectional profile 220 has a radius r that is about 10% to about 25% greater than the thickness 290 of the base flange 200, for example about 10% greater than, about 1 1% greater than, about 12% greater than, about 13% greater than, about 14% greater than, about 15% greater than, about 16% greater than, about 17% greater than, about 18% greater than, about 19% greater than, about 20% greater than, about 21% greater than, about 22% greater than, about 23% greater than, about 24% greater than, or about 25% greater than the thickness 290 of the base flange 200.

[0079] In some embodiments, the filleted cross-sectional profile 220 comprises a non-circular elliptical profile including a major axis 242 and a minor axis 244 that intersect at a geometrical center 230. In some embodiments, the non-circular elliptical profile 220 is truncated and defined at least in part by a geometrical center 230 disposed offset from a geometrical center 230' of a comparative ellipse 240 defined by: a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200; and a comparative minor axis 244’ that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the geometrical center 230 of the noncircular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240’ in one dimension such that the major axis 242 is non-tangential to the top surface 250 of the base flange 200 while the minor axis 244 is tangential to the inner side wall 310 of the exhaust pipe 300. In some embodiments, the geometrical center 230 of the non-circular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240' in one dimension such that the minor axis 244 is non-tangential to the inner side wall 310 of the exhaust pipe 300 while the major axis 242 is tangential to the top surface 250 of the base flange 200. In some embodiments, the geometrical center 230 of the non-circular elliptical profile 220 is offset from the geometrical center 230' of the comparative ellipse 240' in two dimensions such that the major axis 242 is non-tangential to the top surface 250 of the base flange 220 and the minor axis 244 is non-tangential to the inner side wall 310 of the exhaust pipe 300. In some embodiments, the major axis 242 of the non-circular elliptical profile 220 is greater than a comparative major axis 242' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the minor axis 244 of the non-circular elliptical profile 220 is greater than a comparative minor axis 244' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200. In some embodiments, the major axis 242 and the minor axis 244 of the non-circular elliptical profile 220 are each greater than a comparative major axis 242' and a comparative minor axis 244' of a comparative ellipse 240' defined by a comparative major axis 242' that is tangential to a top surface 250 of the base flange 200 and a comparative minor axis 244' that is tangential to an inner side wall 310 of an exhaust pipe 300 disposed in fluid communication with the exit port 210 of the base flange 200.

[0080] In some embodiments, the filleted cross-sectional profile 220 comprises an elliptical filleted cross-sectional profile 220. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to a top surface 250 of the base flange 200. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to an inner side wall 310 of an exhaust pipe 300 configured to be coupled to the base flange 200. In some embodiments, the elliptical filleted cross-sectional profile 220 is tangential to a top surface 250 of the base flange 200 and is tangential to an inner side wall 310 of an exhaust pipe 300 configured to be coupled to the base flange 200.

[0081] In some embodiments, a flow diverter 255 is disposed between the top surface 250 of the base flange 200 and the inside wall 550 of the body portion 500. In some embodiments, the flow diverter 255 is formed integral with the base flange 200. In other embodiments, the flow diverter 255 is formed integral with the inner side wall of the body portion 500. In still other embodiments, the flow diverter 255 is formed separate from the base flange 200 and the inside wall 550 of the body portion 500. The flow diverter 255 in some embodiments includes a planar outermost surface, such as shown specifically in FIGS. 5-8 and 15-18. The planar outermost surface may form a first angle 5 with the top surface 250 and a second angle 0 with the inner side wall 550 of the body portion 500. In some embodiments, the first angle 5 and the second angle 0 are substantially the same or the same. In other embodiments, the first angle 5 is greater than the second angle 0. In still other embodiments, the first angle 5 is less than the second angle 0. In some embodiments, the first angle 5 is about 20° to about 70°, for example about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, about 50°, about 55°, about 60°, about 65°, or about 70°. In some embodiments, the second angle 0 is about 20° to about 70°, for example about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, about 50°, about 55°, about 60°, about 65°, or about 70°. In some embodiments, the first angle 5 is about 40° to about 50° and the second angle 0 is about 40° to about 50°. In some embodiments, the first angle 0 is about 45° and the second angle 0 is about 45°.

[0082] In other embodiments, such as those specifically shown in FIGS. 11 and 14, the flow diverter 255 includes a curved outermost surface. The curved outermost surface may have a convex shape, a concave shape (such as shown in FIGS. 1 1 and 14), or a combination of a convex shape and a concave shape. The radius of the curved concave outermost shape is such that the curve is orthogonal or substantially orthogonal to both the top surface 250 and the inner side wall 550 of the body portion 500. In some embodiments, the curved outermost surface is a truncated curved shape such that the outermost surface of the flow diverter 255 is not tangential to the top surface 250 of the base flange. In other embodiments, the curved outermost surface is a truncated curved shape such that the outermost surface of the flow diverter 255 is not tangential to the inner side wall 550 of the body portion 500 of the associated vacuum relief valve 10. In still other embodiments, the curved outermost surface is a truncated curved shape such that the outermost surface of the flow diverter 255 is not tangential to the inner side wall 550 of the body portion 500 of the associated vacuum relief valve 10 or to the top surface 250 of the base flange.

[0083] For practical reasons or depending on the method of construction, in all cases there may be a small gap between the flow diverter 255 and the wall 510 or the flange surface 250.

[0084] The flow diverter 255 has a radial horizontal width that is less than the radial width of the air column carrying the majority of the air flow in “A” being directed essentially perpendicular to the flange surface 250. In some embodiments, the width of 255 is less than 50% of the width of this air column.

[0085] The flow diverter 255 extends vertically from or from the proximity of flange surface 250 to a height where less than 10% of its radial width extends above the level of the lower surface of float stack 600 when the CARV is operating under vacuum conditions. In some embodiments, the flow diverter 255 would extend only to a height proximate to this level; in other embodiments, flow diverter 255 is less than 40% of this height.

[0086] In some embodiments, the present disclosure provides a vacuum relief valve 10 comprising an exit port 210 configured to enable air A to enter an associated exhaust pipe 300 coupled to the vacuum relief valve 10, wherein the air A entering the exhaust pipe 300 defines a column air, and wherein the column of air occupies all or substantially all of an inside volume 310 of the exhaust pipe 300. In some embodiments, the column of air occupies all or substantially all of the inside volume 310 of the exhaust pipe 300 for at least an initial distance of the exhaust pipe 300 from the vacuum relief valve 10. In some embodiments, the initial distance is at least 1 .5 times an inside diameter 215 of the exit port. In some embodiments, the initial distance is at least 2 times an inside diameter 215 of the exit port. In some embodiments, at least a portion of the column of air reaches a speed of at least about Mach 1 using standard vacuum test conditions of -5.08 psig. In some embodiments, at least a portion of the column of air reaches a speed of at least about Mach 1 .5, before Mach choking essentially plateaus flowrates using vacuum conditions two to about three psig stronger. Methods of Improving Vacuum Relief Performance of a Water or Waste Line

[0087] In some embodiments, the present disclosure provides methods of improving the performance of a waste pipeline in response to changing gas pressures / vacuum conditions.

[0088] Currently, waste pipelines that respond poorly to changes in gas pressure or vacuum conditions are generally improved by removing significant sections of pipe and replacing them with larger diameter pipe and larger-sized CARVs. The cost of these improvement projects in both materials and labor is quite high.

[0089] Much of those high costs may be avoided by replacing CARVs having base flanges that include non-filleted or fully-filleted (e.g., quarter-round) exit port orifices with CARVs 10 consistent with the present disclosure that include a symmetric truncated filleted circular radial profile 220, an asymmetric truncated circular radial profile 220, a symmetric elliptical profile 220, a symmetric truncated elliptical profile 220, or an asymmetric truncated elliptical profile 220. Since CARVs are generally located above ground level or in areas easily accessible, replacement of the existing CARVs with CARVs 10 consistent with the present disclosure may offer significant improvement at a small fraction of the cost.

[0090] In some embodiments, the method of improving waste pipeline performance (e.g., in response to changing gas pressure or vacuum forces) comprises decoupling a preexisting vacuum relief valve from an exhaust pipe, wherein the preexisting vacuum relief valve includes an exit port defined by a base flange that includes a non-filleted cross-sectional profile; and coupling a vacuum relief valve 10 consistent with the present disclosure to the exhaust pipe 300. In some embodiments, the vacuum relief valve 10 includes an exit port 210 surrounded by a base flange 200 including a filleted exit port rim profile 220. In some embodiments, the filleted exit port rim profile 220 has a symmetrical truncated circular radial cross-sectional profile. In other embodiments, the filleted exit port rim profile 220 has an asymmetrical truncated circular radial cross-sectional profile. In other embodiments, the filleted exit port rim profile 220 has a non-truncated non-circular cross-sectional profile. In yet other embodiments, the filleted exit port rim profile 220 has a symmetrical truncated non-circular cross-sectional profile. In still other embodiments, the filleted exit port rim profile 220 has an asymmetrical truncated non-circular cross-sectional profile.

Claims

CLAIMSWhat is claimed is:1 . A base flange for a vacuum relief valve, wherein the base flange comprises an exit port having a filleted cross-sectional profile.

2. The base flange of claim 1 , wherein the filleted cross-sectional profile comprises a truncated circular radial profile.

3. The base flange of claim 2, wherein the truncated circular radial profile has a radius greater than a thickness of the base flange.

4. The base flange of claim 2, wherein the radius is at least 10% greater than the thickness of the base flange.

5. The base flange of claim 2, wherein the radius is at least 15% greater than the thickness of the base flange.

6. The base flange of claim 2, wherein the radius is at least 20% greater than the thickness of the base flange.

7. The base flange of any one of claims 2-6, wherein the truncated circular radial profile is tangential to a top surface of the base flange.

8. The base flange of any one of claims 2-6, wherein the truncated circular radial profile is tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.

9. The base flange of any one of claims 2-6, wherein the truncated circular radial profile is not tangential to a top surface of the base flange.

10. The base flange of any one of claims 2-6, wherein the truncated circular radial profile is not tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.11 . The base flange of any one of claims 2-6, wherein the truncated circular radial profile is not tangential to a top surface of the base flange and is not tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.

12. The base flange of claim 11 , wherein the truncated circular radial profile is defined at least in part by a focal point that is offset from a comparative focal point of a non-truncated circular radial profile such that the truncated circular radial profile is offset from tangent relative to the top surface of the base flange by a first angle a and is offset from tangent relative to the inner side wall of the exhaust pipe by a second angle / 3.

13. The base flange of claim 1 , wherein the filleted cross-sectional profile comprises a noncircular elliptical profile including a major axis and a minor axis that intersect at a geometrical center.

14. The base flange of claim 13, wherein the non-circular elliptical profile is truncated and defined at least in part by a geometrical center disposed offset from a geometrical center of a comparative ellipse defined by: a comparative major axis that is tangential to a top surface of the base flange; and a comparative minor axis that is tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.

15. The base flange of claim 14, wherein the geometrical center of the non-circular elliptical profile is offset from the geometrical center of the comparative ellipse in one dimension such that the major axis is non-tangential to the top surface of the base flange while the minor axis is tangential to the inner side wall of the exhaust pipe.

16. The base flange of claim 14, wherein the geometrical center of the non-circular elliptical profile is offset from the geometrical center of the comparative ellipse in one dimension such that the minor axis is non-tangential to the inner side wall of the exhaust pipe while the major axis is tangential to the top surface of the base flange.

17. The base flange of claim 14, wherein the geometrical center of the non-circular elliptical profile is offset from the geometrical center of the comparative ellipse in two dimensions such that the major axis is non-tangential to the top surface of the base flange and the minor axis is non-tangential to the inner side wall of the exhaust pipe.

18. The base flange of any one of claims 13-17, wherein the major axis of the non-circular elliptical profile is greater than a comparative major axis of a comparative ellipse defined by a comparative major axis that is tangential to a top surface of the base flange and a comparativeminor axis that is tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.

19. The base flange of any one of claims 13-17, wherein the minor axis of the non-circular elliptical profile is greater than a comparative minor axis of a comparative ellipse defined by a comparative major axis that is tangential to a top surface of the base flange and a comparative minor axis that is tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.

20. The base flange of any one of claims 13-17, wherein the major axis and the minor axis of the non-circular elliptical profile are each greater than a comparative major axis and a comparative minor axis of a comparative ellipse defined by a comparative major axis that is tangential to a top surface of the base flange and a comparative minor axis that is tangential to an inner side wall of an exhaust pipe disposed in fluid communication with the exit port of the base flange.21 . A base flange for a vacuum relief valve comprising an exit port having an asymmetric circular radial filleted cross-sectional profile, wherein the asymmetric circular radial filleted cross-sectional profile: is tangential to a top surface of the base flange; and is not tangential to an inner side wall of an exhaust pipe coupled to the base flange.

22. The base flange of claim 21 , wherein the asymmetric circular radial filleted cross-sectional profile has a radius that is about 10% to about 25% greater than a thickness of the base flange.

23. A base flange for a vacuum relief valve comprising an exit port having an elliptical filleted cross-sectional profile.

24. The base flange of claim 23, wherein the elliptical filleted cross-sectional profile is tangential to a top surface of the base flange.

25. The base flange of claim 23, wherein the elliptical filleted cross-sectional profile is tangential to an inner side wall of an exhaust pipe configured to be coupled to the base flange.

26. The base flange of claim 23, wherein the elliptical filleted cross-sectional profile is tangential to a top surface of the base flange and is tangential to an inner side wall of an exhaust pipe configured to be coupled to the base flange.

27. A vacuum relief valve including a base flange of any one of claims 1 -26.

28. A vacuum relief valve comprising an exit port configured to enable air to enter an exhaust pipe coupled to the vacuum relief valve, wherein the air entering the exhaust pipe defines a column air, and wherein the column of air occupies all or substantially all of an inside volume of the exhaust pipe.

29. The vacuum relief valve of claim 28, wherein the column of air occupies all or substantially all of an inside volume of the exhaust pipe for at least an initial distance of the exhaust pipe from the vacuum relief valve.

30. The vacuum relief valve of claim 29, wherein the initial distance is at least 1 .5 times an inside diameter of the exit port.31 . The vacuum relief valve of claim 29, wherein the initial distance is at least 2 times an inside diameter of the exit port.

32. The vacuum relief valve of claim 29, wherein at least a portion of the column of air reaches a speed of at least about Mach 1 .

33. The vacuum relief valve of claim 29, wherein at least a portion of the column of air reaches a speed of at least about Mach 1 .5.

34. The vacuum relief valve of any one of claims 28-33, wherein the base flange is the base flange of any one of claims 1 -26.

35. The base flange of any one of claims 1 -26 further comprising a flow diverter disposed between a top surface of the base flange and an inner side wall of an associated body portion of a vacuum relief valve.

36. The base flange of claim 35, wherein the flow diverter includes a planar outermost surface.

37. The base flange of claim 35, wherein the flow diverter includes a curved outermost surface.

38. The base flange of claim 36, wherein the curved outermost surface is concave.

39. The base flange of claim 37 or claim 38, wherein the curved outermost surface is a truncated curved surface that is not tangential to the top surface of the base flange and / or to the inner side wall of an associated vacuum relief valve.

40. The vacuum relief valve of any one of claims 28-34 further comprising a flow diverter proximal to the exit port and configured to enhance redirection of air flowing towards the exit port without converting the air flowing to a predominantly horizontal direction.41 . The vacuum relief valve of claim 40, wherein the flow diverter includes a planar outermost surface.

42. The vacuum relief valve of claim 40, wherein the flow diverter includes a curved outermost surface.

43. The vacuum relief valve of claim 42, wherein the curved outermost surface is concave.

44. The base flange of claim 42 or claim 43, wherein the curved outermost surface is a truncated curved surface that is not tangential to the top surface of the base flange and / or to the inner side wall of an associated vacuum relief valve.

45. A method of improving vacuum relief performance of a waste line, the method comprising: decoupling a preexisting vacuum relief valve from an exhaust pipe, wherein the preexisting vacuum relief valve includes an exit port defined by a base flange that includes a non-filleted cross-sectional profile; and coupling a vacuum relief valve of any one of claims 27-34 or claims 40-44 to the exhaust pipe.

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