MAV addition valve with constant mass flow orifice protection system

Abstract

MAV addition valve with constant flow nozzle protection system comprising a housing (1) inside of which are fixed, duly sealed and connected by gas channels, a constant flow nozzle assembly (2), an oxygen valve assembly (3), diluent valve assembly (4), oxygen inlet port (5), diluent inlet port (6) and gas outlet port, 5 (7) the constant flow nozzle assembly (2) includes a nozzle body (28) with an oxygen inlet hole (31) connected to an axial hole (32) inside the nozzle body (28), to which a constant flow nozzle (29) with a nozzle orifice (29a) is attached, characterised in that the oxygen inlet opening (31) is covered by a filter using a hydrophobic membrane (34) attached to the nozzle body (28), furthermore, between the central part 10 (30) of the nozzle body (28) and the central part (35) of the chamber (2a) of the nozzle assembly (2), there is a free space (36), which, when the addition button (26) of the oxygen valve assembly (3) is pressed, oxygen flows at high speed.

Description

MAV addition valve with constant mass flow orifice protection system

[0001] The subject of the invention is an MAV addition valve with a constant mass flow orifice protection system intended for use in closed circuit rebreather (CCR) diving systems. The MAV valve (Manual Addition Valve, Manual Add Valve) together with the other elements of the set forms a device called a rebreather (closed-circuit breathing apparatus).

[0002] Closed circuit rebreathers are equipped with a minimum of two gas cylinders. One contains pure oxygen, and the other contains either bottom gas or diluent - air or trimix for deep technical diving. CCR systems can work in many different configurations, depending on the type of dive being carried out, it can be a conventional backmount configuration with one diluent cylinder or two-cylinder set as well as a sidemount configuration with cylinders mounted on the sides of the diver's body. Rebreather allows both recreational diving and specialized technical diving.

[0003] The mCCR, i.e. mechanical rebreathers are based on the principle that with unchanging exertion a person metabolizes a constant quantity of oxygen, which oscillates at about 1 liter / minute (1pm). Additionally, this consumption is independent of depth. This is the reason for using systems that constantly feed an unchanging quantity of oxygen into the breathing loop, close to what we metabolize. CMF ( Constant Mass Flow) is a system that provides a constant flow of oxygen into the system using a mass flow orifice. Under ideal conditions (during a relaxed dive), the quantity of oxygen metabolized by the diver is the same as the quantity of oxygen administered by the mass flow orifice, ensuring an unchanging oxygen content in the breathing loop. During higher exertion and ascent phases, the diver must additionally manually replenish the oxygen content in the breathing loop using the oxygen addition valve (MAV) button. The advantages of mechanical rebreathers are the simplicity of design and the relatively low number of points where failure can occur, as they are based on a regular orifice with a microscopic diameter opening through which oxygen enters the system, independent of other components. These devices do not have computers, solenoid valves or other failure-prone components as is the case with the eCCR. The eCCR, or electronic CCR, is equipped with an electromagnet valve (solenoid), which opens to add oxygen to the breathing loop. Electronic rebreathers have an appropriately programmed computer which, in conjunction with oxygen sensors, maintains preset oxygen content in the gas the diver is breathing.

[0004] Among others, from the US patent description US4273120A "Underwater breathing apparatus" is known an mCCR rebreather with mass flow valve on the oxygen connector and from the US patent description US8272381B2 "Closed circuit rebreather" is known an mCCR rebreather with oxygen control valve (OCV) provided with oxygen connectors and a manual oxygen addition button.

[0005] Existing closed circuit rebreather diving apparatuses today can be equipped with solutions that provide a constant supply of oxygen to the breathing loop in a quantity slightly lower than metabolized by the user (usually 0.5-0.8 1pm). In the case of eCCR units, equipped with an electronically controlled oxygen addition valve, such a solution is optional, while in the case of mCCR units, solutions of this type are commonly used, which is dictated by safety considerations. This solution provides greater safety for diving with mCCR apparatuses, as it maintains a safe oxygen level (partial pressure) in the breathing loop for a longer period of time in situations where the user does not add oxygen with the manual valve.

[0006] Due to the high toxicity of oxygen at high partial pressures, a very important criterion is the ability to very precisely and stably regulate the quantity of supplied gas, regardless of the ambient pressure.

[0007] Two solutions are commonly used in mCCR apparatuses. The first is the needle valve, which allows adjusting the quantity of oxygen delivered depending on the depth (ambient pressure). The second is the constant mass flow orifice, in which the output is correlated with the pressure upstream the orifice, which allows precise adjustment and does not require additional adjustment with changes in depth during the dive.

[0008] The CCR KISS Sidewinder system is equipped with two heads. Each head is connected to a canister of the absorbent bed. In the head of the first scrubber are the bayonet, oxygen and diluent supply hose connections, as well as the automatic diluent valve (ADV). In the head of the second scrubber there are three oxygen sensors with a cable for connecting an oxygen monitoring device, an over pressure relief valve and a bayonet. The set is equipped with an oxygen regulator with constant pressure between stages, and an MAV manual oxygen addition valve, which also includes a constant mass flow orifice. The counterlung is placed behind the scrubber canisters with the absorbent and constitutes the lower connection of the scrubbers.

[0009] "In the Sidewinder unit, oxygen is delivered to the exhaled gas, i.e. the right absorbent canister, through a constant flow orifice (CMF) and, if necessary, manually. The supply hose is mounted in the head. The injection site was placed here to allow time to obtain a homogeneous mixture before measurement - the gas flows through the absorbent canister, the counter-lung and then the second absorbent canister, so that the gas is well mixed before it reaches the oxygen sensors located in the left scrubber head.

[0010] The flow of oxygen from the oxygen regulator with constant interstage pressure is provided by a CMF orifice. This constant mass flow orifice (a small hole placed in the MAV) gives, at a constant input pressure, a precisely defined flow, which is independent of the ambient pressure (within the depth limits specified by the manufacturer of the KISS device, i.e. 93 m). As a result, we get a constant gas flow of a certain value even with an increase in depth. To maintain a constant input pressure, a specially blocked first stage of the regulator was used (instead of the classic flexible diaphragm transmitting the ambient pressure, a Derlin plug was installed). The orifice is located on the exhale side of the loop and the user has easy access to it for maintenance. There is a non-retum valve (non-return valve) between the MAV and the supply hose.

[0011] Instead of the standard MAV, the unit can be equipped with a Dual button MAV that allows manual addition of both oxygen and diluent."

[0012] The two-button MAV addition valve with the constant mass flow orifice of the CCR KISS Sidewinder system constitutes the closest state of the art.

[0013] The opening of the constant mass flow orifice takes the form of a high hardness element, e.g. ceramic or made of crystal - sintered carbide, A12O3aluminum oxide (alumina), ruby or diamond, in which a small diameter opening is made, usually ~5 to ~30 microns. This solution has a number of advantages, such as ease of precise adjustment by changing the pressure prior to the orifice, as well as high safety due to the impossibility of accidental changes in settings. However, it has a major disadvantage, in the form of a high probability of orifice clogging during normal use, which is caused by the microscopic diameter of the orifice opening.

[0014] Currently, the only orifice protection used in mCCR apparatuses are sintered filters, which protect the orifice from dust to some extent (as long as they are replaced regularly), but do not eliminate failures caused by liquid water, particularly salty seawater or calcium-rich water commonly found in karst caves.

[0015] The mechanism of failure involving clogging of the constant mass flow orifice is that water enters its immediate vicinity, which is not caught by the standard sintered filters installed upstream of the orifice. The water then evaporates already inside the unit (downstream the sintered filter) and the dissolved minerals in it, such as salt when it is salty sea water, are deposited on the walls of the orifice seat in the form of solid contamination, which then enters the orifice with the air current, causing clogging.

[0016] MAV addition valve with constant mass flow orifice protection system according to the invention solve the above problems and inconveniences.

[0017] The purpose of the invention is to develop a solution which allows oxygen to flow freely, and which is equipped with a filter which completely eliminates the possibility of liquid water entering the area of the constant mass flow orifice. Additionally,solutions through which water in liquid form will be removed from the surface of the filter, downstream of which there are inlet channels that supply oxygen to the constant mass flow orifice.

[0018] The above tasks were achieved by making an MAV addition valve with a constant mass flow orifice protection system, which, according to the invention, contains a housing inside which the first gas channel connects the opening of the oxygen input port to the chamber of the constant mass flow orifice assembly. A second gas channel connects the constant mass flow orifice assembly chamber to the oxygen valve assembly chamber. A third gas channel connects the oxygen valve assembly chamber to the diluent valve assembly chamber. A fourth gas channel connects the opening of the diluent entry port to the chamber of the diluent valve assembly. A fifth gas channel connects the diluent valve assembly chamber with the constant mass flow orifice assembly chamber. A sixth gas channel connects the chamber of the constant mass flow orifice assembly to the opening of the gas exit port. A constant mass flow orifice assembly, oxygen valve assembly and diluent valve assembly are attached and adequately sealed in appropriate chambers. In the appropriate openings are attached and adequately sealed, oxygen input port, diluent input port and gas output port. The constant mass flow orifice assembly contains the body of the orifice. In the central part of the orifice body is made at least one oxygen inlet opening connected to the axial opening located inside the orifice body. A constant mass flow orifice with an orifice plate is attached to the end of the axial opening. MAV addition valve with constant mass flow orifice protection system, is characterized by the fact that the oxygen inlet opening is covered by a filter attached to the orifice body using a hydrophobic diaphragm. In addition, the central part of the orifice body has a smaller diameter than the central part of the orifice assembly chamber, creating a clear space between the central part of the orifice body and the central part of the orifice assembly chamber. Through the free space, when the addition button of the oxygen valve assembly is pressed, oxygen flows at high speed.

[0019] The solution according to the invention with a filter using a hydrophobic diaphragm ensures the free flow of oxygen, while completely eliminating the possibility of liquid water entering the vicinity of the constant mass flow orifice (29). The filter using hydrophobic diaphragm is characterized by resistance to pure oxygen under high pressure and is also impermeable to liquid water.

[0020] Preferably, the first and second gas channels are placed transverse to the chamber of the constant mass flow orifice assembly.

[0021] The solution according to the invention protects a filter using a hydrophobic diaphragm from, leading to clogging of the filter's micropores, crystallization of calcium and salt compounds on its surface. Placed transversely to the body of the filterorifice, the gas channels supplying oxygen to the oxygen valve assembly cause oxygen to flow at high speed through the free space in the center chamber of the constant mass flow orifice assembly, around the orifice body, toward the oxygen valve assembly, blowing water droplets off the surface of the filter, preventing contaminated water from drying in this area. Liquid water is blown off the surface of the filter every time the addition button of the oxygen valve assembly is pressed.

[0022] Preferably, the first and second gas channels are placed relative to the chamber of the constant mass flow orifice assembly at an angle contained between the axis of the chamber of the constant mass flow orifice assembly and the common axis of the first and second gas channels, the value of which is in the range of 70° to 110°.

[0023] Preferably, the angle value, contained between the chamber axis of the constant mass flow orifice assembly and the common axis of the first and second gas channels, is close to 90°.

[0024] As a result of the tests, it was found that the solution functions optimally when the value of the angle a is within the specified range.

[0025] Preferably, the body of the orifice is provided with a mounting collar, on the cylindrical surface of which a notch is made to form a retaining edge for a locking screw, fixed in an opening made in the housing that passes through the chamber of the constant mass flow orifice assembly.

[0026] The method of fixing the constant mass flow orifice assembly inside the MAV addition valve housing is additionally an advantage of the proposed solution. The described design, using basic tools, allows easy access to the constant mass flow orifice assembly, and thus gives the opportunity to quickly inspect its condition.

[0027] Preferably, the mounting collar of the orifice body has a larger diameter than the central part of the orifice body.

[0028] The larger diameter of the orifice body mounting collar, facilitates during installation, the precise placement of the constant mass flow orifice assembly in the appropriate place of the constant mass flow orifice assembly chamber.

[0029] The object of the invention is presented in an embodiment on the drawing of the MAV addition valve with a constant mass flow orifice protection system, in which:• [Fig-1] presents an exploded view on an isometric view of the MAV addition valve components with a constant mass flow orifice protection system,• [Fig.2] presents on an isometric view the housing of the MAV addition valve with a constant mass flow orifice protection system,• fig. 3 presents on isometric view MAV addition valve with constant mass flow orifice protection system,• [Fig-4] presents a view of the MAV addition valve housing with a constant mass flow orifice protection system from the side of the oxygen valve assembly and diluent valve assembly chambers with the A-A section line marked,• fig. 5 presents cross-section A-A of [Fig.4],• [Fig.6] presents a front view of the oxygen valve assembly,• fig. 7 presents the oxygen valve assembly on an isometric view,• [Fig.8] presents a constant mass flow orifice assembly on an isometric view,• fig. 9 presents a front view of the constant mass flow orifice assembly in a half section,• fig. 10 presents detail A of fig. 9,• [Fig.l 1] presents a view of the MAV addition valve with a constant mass flow orifice protection system from the side of the oxygen valve assembly and diluent valve assembly with the B-B section line marked,• fig. 12 presents a cross-section B-B of [Fig.11],• [Fig.13] presents a cross-section B-B of [Fig.l 1] with the marked successive components of MAV addition valve with constant mass flow orifice protection system,• [Fig.14] presents the flow path of the oxygen stream through the MAV addition valve with a constant mass flow orifice protection system when the oxygen valve is closed in cross-section B-B of [Fig.11]• fig. 15 presents the flow path of oxygen stream through MAV addition valve with constant mass flow orifice protection system when the oxygen valve is open in cross-section B-B of [Fig.11]• [Fig.16] presents schematically the process of removing contaminated water by a stream of oxygen from the surface of a filter using a hydrophobic diaphragm.

[0030] The embodiment presents a two-button MAV addition valve with a constant mass flow orifice protection system designed for use in closed-circuit rebreather (CCR) diving systems.

[0031] The solution presented in the embodiment involves using, upstream the constant mass flow orifice, a filter with properties that allow oxygen to flow freely, while completely eliminating the possibility of liquid water entering the vicinity of the orifice. These conditions are met by filters using a hydrophobic diaphragm (PTFE - polytetrafluoroethylene filters), which are characterized by resistance to pure oxygen under high pressure and are also impermeable to water in liquid form (condensation does not constitute a hazard to the orifice).

[0032] A risk for filters using hydrophobic diaphragm is crystallization of calcium compounds and salts on their surface, leading to clogging of the filter's micropores, as a result of which the flow through the orifice decreases or even stops. The MAV addition valve described in the example embodiment, containing a constant mass flow orifice protected by a filter using a hydrophobic diaphragm, is equipped with a solution by which liquid water is blown off the surface of the filter whenever the oxygen addition button is pressed. Channels supplying gas to the oxygen valve assembly are placed transverse to the orifice body, on which a flat filter using a hydrophobic diaphragm is attached, thanks to which oxygen flowing at high speed, around the orifice body towards the oxygen valve assembly blows off water droplets from the surface of the filter, preventing contaminated water from drying in this area.

[0033] The MAV addition valve with constant mass flow orifice protection system contains a housing (1) inside which the constant mass flow orifice assembly (2), oxygen valve assembly (3), diluent valve assembly (4), oxygen input port (5), diluent input port (6) and gas output port (7) are seated. The housing (1) of the MAV addition valve is provided with an attachment eye (8) that allows it to be hooked up with a diving carabiner. The constant mass flow orifice assembly (2), input ports (5,6) and output port (7) are secured against movement by locking bolts (9). The oxygen valve assembly (3) and the diluent valve assembly (4) are seated using sleeve nuts (10) with screws (11).

[0034] Inside the housing (1) there are a chamber (2a) of the constant mass flow orifice assembly (2), a chamber (3a) of the oxygen valve assembly (3), a chamber (4a) of the diluent valve assembly (4), an opening (5a) of the oxygen input port (5), an opening (6a) of the diluent input port (6) and an opening (7a) of the gas output port (7).

[0035] The openings (9a) of the locking screws (9) pass through the chamber (2a) of the constant mass flow orifice assembly (2), the opening (5a) of the oxygen input port (5), the opening (6a) of the diluent input port (6) and the opening (7a) of the gas output port (7). The openings (9a) of the locking screws (9) are blind and threaded in the lower part.

[0036] The locking screw (9) is in the form of a headless pin, with an Allen key socket and a thread on the lower part of the pin. A notch (12) made on the cylindrical surface of the ports (5,6,7) forms a retaining edge for the locking screw (5), preventing the ports (5,6,7) from falling out or swiveling inside the openings (5a, 6a, 7a). The ports (5,6,7) are sealed with two sealing rings (13). Diving hoses supplying oxygen and diluent are connected to ports (5,6,7), as well as a diving hose discharging gas from the MAV addition valve.

[0037] The openings (10a) of the sleeve nuts (10) pass through the chamber (3a) of the oxygen valve assembly (3) and the chamber (4a) of the diluent valve assembly (4).The openings (10a) of the sleeve nuts (10) are through-holes. The oxygen valve assembly (3) and diluent valve assembly (4) are attached by sleeve nuts (10) with screws (11) in a similar manner to the ports. Whereby the notch (14) is made around the entire circumference of the valve body (23). The circumferential notch (14) forms the retaining edges for the sleeve nut (10) into which the screw (11) is screwed in, preventing the valve assemblies (3,4) from falling out of the chambers (3a, 4a). Sleeve nuts (10) and screws (11) have heads with Allen key sockets. The valve assemblies (3,4) are sealed with two sealing rings (13).

[0038] The chambers (2a, 3a, 4a) of the orifice assembly (2) and valve assemblies (3,4) and the openings (5a, 6a, 7a) of the ports (5,6,7) are, inside the housing (1), connected by six gas channels (15,16,17,18,19,20). The first gas channel (15) connects the opening (5a) of the oxygen input port (5) to the chamber (2a) of the constant mass flow orifice assembly (2). The second gas channel (16) connects the chamber (2a) of the constant mass flow orifice assembly (2) to the chamber (3a) of the oxygen valve assembly (3). The third gas channel (17) connects the chamber (3a) of the oxygen valve assembly (3) with the chamber (4a) of the diluent valve assembly (4). The fourth gas channel (18) connects the opening (6a) of the diluent input port (6) to the chamber (4a) of the diluent valve assembly (4). The fifth gas channel (19) connects the chamber (4a) of the diluent valve assembly (4) with the chamber (2a) of the constant mass flow orifice assembly (2). The sixth gas channel (20) connects the chamber (2a) of the constant mass flow orifice assembly (2) to the opening (7a) of the gas output port (7).

[0039] The first (15) and second (16) gas channels are positioned transverse to the chamber (2a) of the constant mass flow orifice assembly (2), at an angle (a) close to 90°. In the embodiment, the angle (a) between the axis (21) of the chamber (2a) of the constant mass flow orifice assembly (2) and the common axis (22) of the first (15) and second (16) gas channels is 98°. As a result of the tests, it was found that the solution functions optimally when the value of the angle (a) is within the range of 70° to 110°.

[0040] The oxygen valve assembly (3) and diluent valve assembly (4) are made according to solutions known in the state of the art. The oxygen valve assembly (3) and the diluent valve assembly (4) contain, sealed with two ring gaskets (13), a valve body (23) with a circumferential notch (14) for the sleeve nut (10). The valve body (23) has a gas inlet opening (24). Inside the valve body (23) a piston (25) sealed with two ring gaskets (13) moves. Attached to the piston (25) is an addition button (26) that works with a spring (27). Pressing the addition button (26) opens the valve, and releasing it closes the valve.

[0041] The constant mass flow orifice assembly (2) for oxygen is cylindrical in shape and contains, sealed with two ring gaskets (13), an orifice body (28) and a constant mass flow orifice (29). In the embodiment example, three oxygen inlet holes (31) are madein the central part (30) of the orifice body (28), connected to the axial hole (32) located inside the orifice body (28). The axial opening (32) is threaded from the face.

[0042] The constant mass flow orifice (29) together with the orifice plate (29a) is made according to the solutions known in the state of the art, the orifice can be in the form of a high hardness element, e.g. ceramic or made of crystal - sintered carbide, A12O3 aluminum oxide (alumina), ruby or diamond. The constant mass flow orifice (29) is in the form of a hexagonal screw with a cone ending with an orifice (29a). Inside the orifice, an opening (29b) with a larger diameter is made and in the orifice (29a) a hole with a diameter (d) of 5 pm - 30pm is made. To better illustrate the solution in question, the figures of the embodiment present the diameter (d) of the orifice opening (29a) larger than in reality. The constant mass flow orifice (29) is provided with a thread (29c) so that it can be screwed into the axial opening (32) of the orifice body (28).

[0043] The orifice body (28) is provided with a mounting collar (33), on the cylindrical surface of which a notch (12) is made to form a retaining edge for the locking screw (5), preventing the constant mass flow orifice assembly (2) from falling out of the housing (1) or swiveling inside the chamber (2a). The mounting collar (33) of the orifice body (28) has a larger diameter than the central part (30) of the orifice body (28).

[0044] The method of attaching the constant mass flow orifice assembly (2) inside the housing (1) of the MAV addition valve is additionally an advantage of the solution presented in the embodiment. The described design, with the use of a basic tool in the form of an Allen key, allows easy access to the constant mass flow orifice assembly (2), and thus provides the opportunity to quickly inspect its condition. The larger diameter of the orifice body (28) mounting collar (33), facilitates during installation, the precise placement of the constant mass flow orifice assembly (2) in the appropriate place of the constant mass flow orifice (2) assembly chamber (2a).

[0045] The oxygen inlet openings (31) are protected by a filter attached to the orifice body (28) and using a hydrophobic diaphragm (34). The embodiment uses a PTFE (polytetrafluoroethylene) filter in the form of a GORE® self-adhesive hydrophobic diaphragm for ventilation.

[0046] The solution according to the invention with a filter using a hydrophobic diaphragm (34) GORE® ensures the free flow of oxygen, while completely eliminating the possibility of liquid water entering the vicinity of the constant mass flow orifice (29). The PTFE (34) GORE® filter is characterized by resistance to pure oxygen under high pressure and is also impermeable to liquid water.

[0047] The central part (30) of the orifice body (28) has a smaller diameter than the central part (35) of the chamber (2a) of the orifice assembly (2) so that there is a free space(36) between them, thanks to which, when the addition button (26) of the oxygen valve assembly (3) is pressed, oxygen flows at high pressure. Oxygen flowing at high speed, flowing around the central part (30) of the orifice body (28) removes contaminated water from the surface from the filter (34). The water, along with oxygen, travels through the diving hoses and is collected in a water trap located in the rebreather head.

[0048] The flow of the oxygen stream (37) is shown on fig. 15, [Fig.16] and fig. 17 of the drawing.

[0049] fig. 15 depicts the flow path of the oxygen stream (37) through the MAV addition valve with the oxygen valve (3) closed on the B-B section.

[0050] The oxygen stream (37) enters through the oxygen input port (5) and through the first gas channel (15) enters the free space (36) between the orifice body (28) and the chamber (2a) of the orifice assembly (2). It continues to flow through the GORE® PTFE filter (34) and flows through the oxygen inlet holes (31) into the axial opening (32) inside the orifice body (28).

[0051] Then a specific quantity of oxygen, dependent on the diameter (d) of the orifice opening (29a), flows through the orifice opening (29a) of the constant mass flow orifice (29) and through the sixth gas channel (20) flows out of the MAV addition valve through the gas output port (7).

[0052] [Fig.16] depicts the flow path of the oxygen stream (37) through the MAV addition valve with the oxygen valve (3) open on the B-B section.

[0053] fig. 17 depicts schematically the process of removing contaminated water (38) by a stream of oxygen (37) from the surface of a PTFE filter (34).

[0054] The oxygen stream (37) enters through the oxygen input port (5) and through the first gas channel (15) enters the free space (36) between the orifice body (28) and the chamber (2a) of the orifice assembly (2). The oxygen jet (37), flowing at high speed and pressure around the central part (30) of the orifice body (28) with the GORE® PTFE filter (34) attached, removes contaminated water (38) from its surface and flows out through the second gas channel (16). The stream of gas (37), entering through the inlet opening (24) of the oxygen valve, successively flows through the oxygen valve assembly (3), the chamber (3a) of the oxygen valve (3a), the third gas channel (17), the chamber (4a) of the diluent valve (4), the fifth gas channel (19) and the sixth gas channel (20) and then flows out with water (38) from the MAV addition valve through the gas output port (7). Since in this case part of the oxygen stream (37) flows through the constant mass flow orifice (29) all the time, the second gas channel (16) can have a smaller diameter than the first gas channel (15).

[0055] The solution according to the invention protects the GORE® PTFE filter (34) prior to crystallization of calcium and salt compounds on its surface, leading to clogging of the filter's (34) micropores. Placed transverse to the orifice body (28) with the filter(34), the channels (15, 16) supplying oxygen to the oxygen valve assembly (3) cause oxygen to flow at high speed through the free space (36) in the central part (35) of the chamber (2a), around the orifice body (28), towards the oxygen valve assembly (3), blowing water droplets off the surface of the filter (34), preventing contaminated water from drying in this area. Liquid water is blown off the surface of the filter (34) every time the addition button (26) of the oxygen valve assembly (3) is pressed.List of designations:

[0056] 1 MAV addition valve housing with constant mass flow orifice protection system

[0057] 2 Constant mass flow orifice assembly

[0058] 2a Constant mass flow orifice assembly chamber

[0059] 3 Oxygen valve assembly

[0060] 3a Oxygen valve assembly chamber

[0061] 4 Diluent valve assembly

[0062] 4a Diluent valve assembly chamber

[0063] 5 Oxygen input port

[0064] 5a Oxygen input port opening

[0065] 6 Diluent input port

[0066] 6a Opening of the diluent input port

[0067] 7 Gas output port

[0068] 7a Opening of the gas output port

[0069] 8 Housing attachment eyelet

[0070] 9 Locking screw

[0071] 9a Opening of the locking screw

[0072] 10 Sleeve nut

[0073] 10a Opening of the sleeve nut

[0074] 11 Screw

[0075] 12 The notch made on the cylindrical surface of the port and the notch made on the cylindrical surface of the mounting collar of the constant mass flow orifice body

[0076] 13 Sealing ring

[0077] 14 Circumferential notch of the body of the oxygen valve assembly and the body of the diluent valve assembly

[0078] 15 First gas channel

[0079] 16 Second gas channel

[0080] 17 Third gas channel

[0081] 18 Fourth gas channel

[0082] 19 Fifth gas channel

[0083] 20 Sixth gas channel

[0084] 21 Axis of the chamber of the constant mass flow orifice assembly

[0085] 22 Common axis of the first and second gas channels

[0086] 23 Oxygen and diluent valve body

[0087] 24 Gas input opening to oxygen valve body and diluent valve

[0088] 25 Oxygen and diluent valve piston

[0089] 26 Oxygen and diluent valve addition button

[0090] 27 Oxygen and diluent valve spring

[0091] 28 Constant mass flow orifice body

[0092] 29 Constant mass flow orifice

[0093] 29a Constant mass flow orifice plate

[0094] 29b Opening inside the constant mass flow orifice

[0095] 29c Constant mass flow orifice thread

[0096] 30 Central part of the constant mass flow orifice body

[0097] 31 Oxygen inlet openings of the constant mass flow orifice body

[0098] 32 Axial opening inside the constant mass flow orifice body

[0099] 33 Orifice body mounting collar

[0100] 34 Filter using hydrophobic diaphragm - PTFE filter

[0101] 35 Central part of the constant mass flow orifice chamber

[0102] 36 Free space between the central part of the orifice body and the central part of the orifice assembly chamber

[0103] 37 Oxygen stream

[0104] 38 Droplets of water

[0105] D Constant mass flow orifice opening diameter

[0106] a Angle a between the chamber axis of the constant mass flow orifice assembly and the common axis of the first and second gas channels

Claims

Claims

1. An MAV addition valve with constant mass flow orifice protection system containing housing (1), inside of which the first gas channel (15) connects the opening (5a) of the oxygen input port (5) with the chamber (2a) of the constant mass flow orifice assembly (2), the second gas channel (16) connects the chamber (2a) of the constant mass flow orifice assembly (2) with the chamber (3a) of the oxygen valve assembly (3), the third gas channel (17) connects the chamber (3a) of the oxygen valve assembly (3) with the chamber (4a) of the diluent valve assembly (4), the fourth gas channel (18) connects the opening (6a) of the diluent input port (6) with the chamber (4a) of the diluent valve assembly (4), the fifth gas channel (19) connects the chamber (4a) of the diluent valve assembly (4) with the chamber (2a) of the constant mass flow orifice assembly (2), the sixth gas channel (20) connects the chamber (2a) of the constant mass flow orifice assembly (2) with the opening (7a) of the gas output port (7), in the appropriate chambers (2a, 3a, 4a) the constant mass flow orifice assembly (2), oxygen valve assembly (3) and diluent valve assembly (4) are attached and adequately sealed, and the oxygen input port (5), diluent input port (6) and gas output port (7) are attached and adequately sealed in the appropriate openings (5a, 6a, 7a); the constant mass flow orifice assembly (2) containing an orifice body (28), at least one oxygen inlet port (31) connected to an axial port (32) located inside the orifice body (28) is made in the central part (30) of the orifice body (28), and a constant mass flow orifice (29) with an orifice plate (29a) is attached to the end of the axial port, characterized in that the oxygen inlet opening (31) is covered by a filter using a hydrophobic diaphragm (34) attached to the orifice body (28), additionally, the central part (30) of the orifice body (28) has a smaller diameter than the central part (35) of the chamber (2a) of the orifice assembly (2), forming a free space (36) between the central part (30) of the orifice body (28) and the central part (35) of the chamber (2a) of the orifice assembly (2), which, when the addition button (26) of the oxygen valve assembly (3) is pressed, flows oxygen at high speed.

2. An MAV addition valve with constant mass flow orifice protection system according to claim 1 characterized in that the first (15) and second (16) gas channels are placed transverse to the chamber (2a) of the constant mass flow orifice assembly (2).

3. An MAV addition valve with constant mass flow orifice protection system according to claim 1 characterized in that the first (15) and second (16) gas channels are placed relative to the chamber (2a) of the constant mass flow orifice assembly (2) at an angle (a) contained between the axis (21) of the chamber (2a) of the constant mass flow orifice assembly (2) and the common axis (22) of the first (15) and second (16) gas channels, the value of which is in the range of 70° to 110°.

4. An MAV addition valve with constant mass flow orifice protection system according to claim 3 characterized in that the value of the angle (a), contained between the axis (21) of the chamber (2a) of the constant mass flow orifice assembly (2) and the common axis (22) of the first (15) and second (16) gas channels, is close to 90°.

5. An MAV addition valve with a constant mass flow orifice protection system according to any of the claims 1 to 4, characterized in that the orifice body (28) is provided with a mounting collar (33), on the cylindrical surface of which is made a notch (12) forming a retaining edge for a locking screw (5), fixed in an opening (9a) made in the housing (1) passing through the chamber (2a) of the constant mass flow orifice assembly (2).

6. An MAV addition valve with constant mass flow orifice protection system according to claim 5, characterized in that the mounting collar (33) of the orifice body (28) has a larger diameter than the central part (30) of the orifice body (28).

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