A system for restoring the indicator of a measurement instrument and for protecting said indicator from pressure fluctuations

Abstract

A system for restoring the indicator (i) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations comprises: a fixed sealing apparatus (GS) configured to be installed between the indicator (i) and a capillary tube (TC) of the measurement instrument, said measurement instrument being provided with a flexible membrane (M) inserted in a separator (S) and immersed in a receptacle and in contact with the fluid whose quantity (pressure or level) is to be measured, said fixed sealing apparatus (GS) acting as a receiving element for restoring the transmission gas during the replacement steps for the indicator (i) and acting as a protection element against overpressures during the normal operation of the measurement instrument; a removable recharge pump (RP) connectable to said fixed apparatus (GS) for restoring the transmission gas. Said fixed apparatus (GS) allows for replacement of said indicator (i) without necessarily having to replace the entire instrument and without resulting in a system shutdown or during particularly complex and costly operations.

Description

A SYSTEM FOR RESTORING THE INDICATOR OF A MEASUREMENTINSTRUMENT AND FOR PROTECTING SAID INDICATOR FROM PRESSURE FLUCTUATIONS

[0001] The present invention belongs to the field of pressure or level measurement instruments adapted to be installed in systems, e.g., on tanks or low-pressure fluid transport lines.

[0002] More specifically, the invention relates to an apparatus capable of facilitating the operations of replacing an indicator, which is faulty or no longer suitable, without resulting in a system shutdown or carry out complex or costly interventions.

[0003] Pressure or level measurement instruments are well known in the background art; these manometric devices are essential for monitoring and ensuring the safe operation of equipment and processes in various sectors, such as, for example, the naval sector.

[0004] It is known that such instruments are available in various styles, such as self-powered dial gauges, to adapt to different applications and preferences .

[0005] Furthermore, they may provide various types of measurement, such as the tank level and / or volume, providing valuable data for process control and safety management.

[0006] it is known that a generic measurement system, for example for measuring the level, may consist of a membrane separator and an indicator connected by means of a capillary tube, in which the membrane is positioned inside the container whose liquid level and / or volumeis to be measured.

[0007] The membrane is in contact on one side with the fluid whose quantity (pressure or level) is to be measured, and on the other side with a gas adapted to "transfer" to the indicator, by means of the connection provided by the capillary tube, any changes resulting from the deformation of the membrane, due to changes in the monitored fluid.

[0008] However, it may occur that, on completion of assembly or during the scheduled system checks, the value of the actual measurement does not correspond to the reading on the instrument.

[0009] This may depend, for example, on an incorrect movement, which damaged the indicator / capillary / membrane assembly or modifications to the receiving element and thus, to the volume or level to be measured, or a loss of functionality and / or precision of the instrument, or on the fact that the tank is used for a liquid having a specific weight different to the one originally provided.

[0010] All these possible drawbacks render the measurement unit inefficient, resulting in the consequent need to replace the entire instrument, also when the fault or possible correction is exclusively localized in the indicator thereof.

[0011] indeed, as it is a unit whose elements are completely joined, currently, it is impossible to replace only the malfunctioning indicator with a new one without entirely replacing all the measurement instrument (therefore also the membrane and capillary tube), because replacing only the indicator would alterthe pressurization of the transmission gas placed inside the capillary tube, definitively compromising the possibility of restoring a correct reading.

[0012] On the other hand, replacing the entire measurement instrument, as stated previously, generally involves high costs due to the need to stop the entire system or at least the specific section, or in any case due to the need to empty the tanks in order to proceed with the replacement.

[0013] Furthermore, in cases where the monitored fluid is toxic or poses issues for the maintenance personnel, it is necessary to carry out a reclamation before proceeding with replacing the instrument, thus significantly increasing the expense required for the replacement.

[0014] it is the task of the invention to overcome the limitations of the prior art by providing a device allowing a simple replacement of the malfunctioning indicator without needing system shutdowns or act on the system and without needing to reclaim the monitored system.

[0015] The suggested solution is an apparatus installable between the indicator (i) and the capillary tube (T) of a generic measurement instrument, adapted to allow only the replacement of the indicator in the event of failure and to allow the refilling of the gas within the instrument circuit.

[0016] A better understanding of the invention will be obtained with the following detailed description and with reference to the accompanying figures, showing a preferred embodiment by way of non-limiting example.

[0017] Figure 1 is a generic installation diagram of a common measurement instrument inside a receptacle.

[0018] Figure 2 is a top sectional view of the gas passage duct according to the invention.

[0019] Figure 3 is a lateral sectional view of the gas passage duct according to the invention.

[0020] Figure 4 is a lateral sectional view of the recharge pump according to the invention.

[0021] As stated, the invention substantially consists of a system that allows replacing the indicator of the measurement instrument without necessarily having to replace the entire instrument and without having to empty the tank; according to the invention, said apparatus also protects the indicator from both accidental and continuous pressure fluctuations, when occur ri ng .

[0022] in a preferred, but non-limiting embodiment, said system comprises two devices:• A fixed sealing apparatus (GS) installable between the indicator (i) and the capillary tube (TC) of a generic measurement instrument provided with a flexible membrane (M) inserted in a separator (s) and immersed in a receptacle and in contact with the fluid whose quantity (pressure or level) is to be measured, said fixed sealing device (GS) acting as a receiving element for restoring the transmission gas during the replacement steps for the indicator (i) and acting as a protection element against the overpressures during the normal operation of the measurement instrument;• A removable recharge pump (RP) connectable to said fixed apparatus (GS) for restoring the transmissiongas.

[0023] in the described preferred, but non-limiting embodiment, said fixed sealing apparatus (GS) consists of a “T-shaped connection” body and comprises the following elements:• A middle body (1) inside which there are channels (B, C, D) for the flowing of the transmission gas of the signal and for housing the elements required for isolating and protecting against the overpressures;• An adjustment spring bearing side body (2) connected to said middle body (1) at the lower part of the channel (D) ;• A closing cap (3) lockable on the upper part of said body (1) above the channel (C) ;• A threaded connection (4) for connecting to the indicator and internally provided with a channel (E) communicating and coaxial with the transmission duct (D) of the middle body (1);• A calibration spring (5) placed inside the side body (2);• A sealing o-ring (6) placed inside the middle body (1) in the boundary zone between channels (C) and (D) ;• A piston (7) placed inside the middle body (1), said piston being suitably shaped so as to have multiple coaxial cylindrical sections, in which at least one section is placed above said sealing o-ring (6) inside the channel (C) , while the remaining part is entirely placed inside the channel (D) ;• A connection (8) for connecting to the capillary tube and internally provided with a channel (A) converging inside the transmission duct (B) of the middle body(1);• A plate (9) belonging to the modulating group placed at the lower end of the piston (7) and therefore at the lower zone of the channel (D) and above the lateral adjustment body (2), said plate being shaped so as to slide up to abutment inside a specific seat (9a) obtained inside the body (2);• A membrane (10) belonging to the modulating group placed at the lower end of the piston (7) and therefore at the lower zone of channel (D) and above the lateral body (2) containing the adjustment spring (5), said membrane being integral with the plate (9) and with the edge welded to the middle body (1);• A reaction spring (11) placed coaxially to the piston (7) above the plate (9);• A calibration screw (12) placed below the calibration spring (5), which rotation allows acting on the deformation of said spring (5);• A recharge duct (13) transverse to the channel (B) ;• A sealing conical -headed pin (14), an end of which allows gas leaks from the duct (13) to be avoided;• A protective cap (15) placed at the opposite end of the pin (14) in the housing dedicated to the recharge pump.

[0024] in the described preferred, but non- limiting embodiment, said fixed sealing apparatus (GS) may be made of various materials, including 316i_ stainless steel, brass, and titanium.

[0025] in the described preferred, but non-limiting embodiment, said removable recharge pump (RP) , connectable to said fixed apparatus (GS) , is syringe-shaped and comprises the following elements:• A substantially cyl indri cal -shaped outer casing (17) ending in a conical section at one end and containing a hollow and suitably shaped internal plunger;• A knob (18) integral with the inner plunger (19) of the recharge pump and such to allow the translation of said internal plunger by means of rotation;• A stop ring (20);• Preferably, a simple Allen maneuvering key or torque wrench (21) adapted to maneuver the pin (14), said maneuvering key being insertable inside the cavity of the plunger;• A sealing O-ring (22) for avoiding gas leaks towards the outside;• An abutting O-ring (23) adapted to allow the correct tightening of the recharge pump (RP) inside the dedicated housing, placed on the fixed sealing apparatus (GS) ;• A gas filling volume (24);• An internal sealing O-ring (25) placed between the maneuvering key and the cavity of the internal plunger, adapted to avoid gas leaks in the various steps ;• A protective cap (26).

[0026] in a preferred, but non-limiting embodiment, said recharge pump (RP) is made with an aluminum outer body.

[0027] As said, the apparatus according to the invention is installed between the indicator (i) and the capillary tube (TC) of the measurement instrument, whether the latter is of a new design or an old designinstrument, provided that it has a capillary tube screwed to an indicator in which the signal transmission occurs by means of the gas flow.

[0028] During the normal operation of the measurement instrument, the gas trapped inside the measurement system flows into the apparatus through the channels (A, B, C, D, E) , proportionally compressing and decompressing with respect to the deformation of the membrane (M) placed in contact with the fluid whose quantity is to be measured.

[0029] Once installed as indicated and in the event of malfunctioning or inadequacy of just the indicator (i) , the system according to the present invention allows replacing the faulty indicator (i) or no longer suitable for the field of use, with an adequate, correctly working one, enabling it to be recharged and allowing the complete restoration of the measurement instrument without resulting in a system shutdown or emptying the entire system (with possible reclamation depending on the monitored fluids).

[0030] The recharge function, i.e., restoring the ai r / gas volume inside the system, which depressurizes during the operation of replacing the manometer, is carried out using the recharge pump (RP).

[0031] Once the faulty indicator (i) has been removed and the new one installed, the following operations are carried out:• Removing the protective caps (16) (26);• unscrewing the knob (18) to provide the maximum volume of ai r / gas (24) ;• Screwing the recharge pump (RP) onto the appropriatethread of the middle body (1) placed on the fixed sealing apparatus (GS) in place of the cap (16), manually tightening until the O-ring (23) is abutting;• inserting the Allen maneuvering key (21) by engaging the Allen key of the pin (14);• unscrewing the pin (14) by rotating the Allen maneuvering key (21), allowing the gas to pass from the pump of the SPG system (and similar);• Rotating the screw (18) until the end stop, allowing the transfer of the gas volume contained in the pump into the ducts of the measurement instrument;• Adjusting the mechanical seal on the pin (14) by acting on the Allen maneuvering key (21) so as to ensure a perfect mechanical seal;• if liquid is contained inside the tank, the index of the indicator (i) will gradually reach the position indicating the height (volume) of the liquid;• Once the procedure is complete, unscrew the body of the recharge pump (RP) from the fixed sealing apparatus (GS) and reassemble the cap (16).

[0032] As said previously, during the normal operation, the gas trapped inside the measurement instrument flows into channels A, B, C, D, E.

[0033] if the pressure in the system exceeds the value determined during the design phase and calibrated on the calibration spring (5) by the adjustment screw (12), the modulating group, consisting of the membrane (10) and the plate (9), overcomes the force of the calibration spring (5), allowing the piston (7) with the reaction spring (11) to press the o-ring (6) against the seat and, consequently, intercept the flow from zone (C) tothe duct (D) .

[0034] This prevents an excessive increase in the gas pressure towards the indicator, protecting it from pressure values greater than those allowed, thus preventing damage to the receiving group.

[0035] According to the invention, the membrane (10) of the modulating group is welded to the body (1) to avoid leaks in the hermetically sealed system of the SPG or equivalent.

[0036] Likewise, the cap (3) creates a metal seal to avoid leaks on the side thereof.

[0037] After restoring the pressure within the determined limits of the calibration spring (5), the spring will distance the O-ring (6) from the seat, allowing ai r / gas to pass from the membrane (M) positioned in the separator to the indicator (i) .

[0038] Advantageously, the apparatus according to the invention ensures protection against overpressure up to over 30 mH2O (meters of water column).

[0039] Basically, the combined action of the modulating group, consisting of the plate (9) and the membrane (10) integral with the piston (7), the calibration spring (5), which may be calibrated by means of the adjustment screw (12), and the particular geometry of the gas circulation channels allow, in the event of overpressure, intercepting the gas inside the sealing apparatus (GS) , preventing damage to the indicator (i) .

Claims

CLAIMS1. A system for restoring the indicator (i) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations, character zed in that it comprises:• A fixed sealing apparatus (GS) configured to be installed between the indicator (i) and a capillary tube (TC) of the measurement instrument, said measurement instrument being provided with a flexible membrane (M) inserted in a separator (s) and immersed in a receptacle and in contact with the fluid whose quantity (pressure or level) is to be measured, said fixed sealing apparatus (GS) acting as a receiving element for restoring the transmission gas during the operations of replacing the indicator (i) and acting as a protection element against overpressures during the normal operation of the measurement instrument;• A removable recharge pump (RP) connectable to said fixed apparatus (GS) for restoring the transmission gas; wherein said fixed apparatus (GS) is configured to allow said indicator (i) to be replaced without necessarily having to replace the entire instrument and without resulting in a system shutdown or in particularly complex and costly operations.

2. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to the preceding claim, characterized in that said sealing apparatus (GS) comprises the following elements:• A middle body (1) inside which there are channels (B, C, D) for the flowing of the transmission gas of the signal and for housing the elements required for isolating and protecting against the overpressures;• A side cylindrical adjustment body (2) provided with openings on both circular sections, said side cylindrical body being connected to said middle body(1) at the lower part of the channel (D) ;• A closing cap (3) screwed onto the upper part of said body (1) above the channel (C) ;• A threaded connection (4) welded to the body (1) for connection to the indicator (i) and internally provided with a channel (E) which is coaxial to the transmission duct (D) of the middle body (1);• A calibration spring (5) placed inside the side body(2);• A sealing o-ring (6) placed inside the middle body (1) in the boundary zone between channels (C) and (D) ;• A piston (7) placed inside the middle body (1), said piston being suitably shaped in order to have several coaxial cylindrical sections and wherein at least one section is placed above said sealing o-ring (6) inside the channel (C) , while the remaining part is completely placed inside the channel (D) ;• A connection (8) welded to the body (1) for connection to the capillary tube and internally provided with a channel (A) converging inside the transmission duct (B) of the middle body (1);• A plate (9) belonging to the modulating group placed at the lower end of the piston (7), and therefore at the lower zone of the channel (D) and above theadjustment body (2), said plate being shaped so as to slide up to abutment inside a specific seat (9a) obtained inside the body (2);• A membrane (10) belonging to the modulating group placed at the lower end of the piston (7), and therefore at the lower zone of the channel (D) and above the adjustment duct (2), said membrane being integral with the plate (9) and with the ends of the middle body (1), thus allowing to avoid gas leaks from the channel (D) towards the adjustment duct (2) and, therefore, towards the outside;• A reaction spring (11) placed coaxially to the piston (7) above the plate (9);• A calibration screw (12) placed below the calibration spring (5), which rotation allows acting on the deformation of said spring (5);• A recharge duct (13) transverse to the channel (B) ;• A sealing conical -headed pin (14), an end of which allows gas leaks from the duct (13) to be avoided.

3. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to claim 2, characterized in that said sealing apparatus (GS) is provided with a safety cap (16) placed at the end opposite to the pin (14) in the housing dedicated to the recharge pump.

4. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to one or more of the preceding claims, characterized in that said recharge pumpcomprises the following elements:• A substantially cyl indri cal -shaped outer casing (17) ending in a conical section at one end and containing a hollow and suitably shaped internal plunger;• A knob (18) integral with the inner plunger of the recharge pump and such as to allow the translation of said internal plunger by means of rotation;• An internal plunger (19) of the recharge pump;• A stop ring (20);• A simple Allen maneuvering key or torque wrench (21) adapted to maneuver the pin (14), said maneuvering key being insertable inside the cavity of the plunger;• A sealing O-ring (22) for avoiding gas leaks towards the outside;• An abutment o-ring (23) adapted to allow the correct tightening of the recharge pump (RP) inside the dedicated housing placed on the fixed sealing duct;• A gas filling volume (24);• An internal sealing O-ring (25) placed between the maneuvering key and the cavity of the internal plunger, adapted to avoid gas leaks in the various steps .

5. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i)) from both continuous and accidental pressure fluctuations according to claim 4, characterized in that said recharge pump (RP) is provided with a safety cap (26).

6. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressurefluctuations according to one or more of the preceding claims, characterized in that said sealing apparatus (GS) may be made of various materials, including 316i_ stainless steel, brass and titanium.

7. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to one or more of the preceding claims, characterized in that the cylinder of said recharge pump (RP) is made with an aluminum outer body.

8. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to one or more of the preceding claims, characterized in that it is configured to allow, in the event of indicator (i) breaking, replacing the latter and restoring the volume of ai r / gas inside the system by simply replacing just the no longer adequate or malfunctioning indicator (l) with a new one, without experiencing system shutdowns nor possible tank emptying and reclamation operations, as well as reintegrating the gas required to move the index on the indicator dial using the recharge pump (RP) .

9. A system for restoring the indicator (l) of a measurement instrument and for protecting said indicator (i) from both continuous and accidental pressure fluctuations according to one or more of the preceding claims, characterized in that the combined action of the modulating group, consisting of the plate (9) and the membrane (10) which are integral with the piston (7), the calibrating spring (5) which is adjustable by meansof the calibrating screw (12), and the particular geometry of the gas circulating channels, allow the gas inside the sealing apparatus (GS) to be intercepted in the event of overpressure up to 30 m of water column, thus avoiding damage to the indicator (i) .

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