WO2004087497A2

WO2004087497A2 - Snorkel air inlet valve

Info

Publication number: WO2004087497A2
Application number: PCT/EP2003/003422
Authority: WO
Inventors: Adrian Cox
Original assignee: Adrian Cox
Priority date: 2003-04-02
Filing date: 2003-04-02
Publication date: 2004-10-14
Also published as: WO2004087497A3; EP1608552A2; AU2003222789A1; WO2004087497A8

Abstract

A snorkel air inlet valve (11) comprises a disc valve (21) pivoted inside a snorkel extension pipe (19), a float (17) that encircles the snorkel extension pipe (19) and swings parallel to and in parallel motion along the snorkel extension pipe (19) on the ends of horseshow shaped swing bars (37, 39) that are positioned parallel to another and encircle the snorkel extension pipe (19) and are pivoted on axis lines that pass through the centre of the snorkel extension pipe (19), an L-shaped bridging bush bar (29) mounted on the float (17) and reaching through a slot into the inner of the snorkel extension pipe (19) and pivotally holding one end of a crank wire (23) of which the other end is fixed to the disc valve (21) off-axis such that as the float (17) swings along the snorkel extension pipe (19) the L-shaped bridging bush bar (29) moved therewith moves the crank wire (23) which in turn adjusts the pitch of the valve disc (21 ). A single loop spiral spring (31) encircling and mounted to the snorkel extension pipe (19) applies a force on the float (17) in the direction which assists the closing of valve disc (21) within snorkel extension pipe (19).

Description

Snorkel Air Inlet Valve

The invention is of the type that would be fixed to the air-inlet end of a snorkel, worn by a swimmer to enable him to breath with his head under water, in order to prevent water from entering the said air inlet-end of the snorkel when submerged.

The present invention concerns a snorkel air inlet valve of the type comprising of a snorkel pipe extension and a float, which having a lower gravitational pull than water, rises further up the said snorkel pipe extension on submergence in water, closing an air-valve in the process, thus preventing water from passing through the said snorkel air inlet valve into the snorkel.

The advantage of a snorkel air inlet valve is that it prevents water from small waves, that are big enough to engulf the entire length of the snorkel but not big enough to raise the snorkeller in the water himself, from entering the snorkel tube and being channelled directly into the lungs of the snorkeller who would not be able to foresee such an occurrence in order to take preventive action.

A second advantage of a snorkel air inlet valve is that it enables the snorkeller to dive spontaneously without first of all having to raise his head out of the water to remove the snorkel form his mouth, which would otherwise channel water directly into his lungs once submerged unless he blocks the air-passageway of the mouthpiece of the said snorkel with his tongue being both unpleasant and a hazard to the health of the said snorkeller as the said tongue of the said snorkeller, being both sensitive and a direct channel to the bloodstream of the said snorkeller, would then for sustained periods of time be exposed to low temperatures, germs and hazardous chemicals that may exist in the water surrounding the said snorkeller.

A third advantage of a snorkel air inlet valve is that it creates an airlock in the snorkel which acts as an extension of the lungs of the snorkeller thus increasing his oxygen reserve und consequently the length of time he can spend submerged.

A forth advantage of a snorkel air inlet valve is that it, when the snorkeller is submerged with the snorkel in his mouth, together with the pressure of water pressing the lips of the snorkeller naturally onto the mouthpiece of the snorkel creating a natural seal, carries the said pressure of water trying to enter into the said snorkel and consequently into the lungs of the said snorkeller. Without this said snorkel, combined with the said snorkel air inlet valve, the said snorkeller would be forced to press his lips hard together in order to withstand the said pressure of the water trying to enter his lungs, thus raising the level of mental stress on the snorkeller and leaving the possibility open that the said snorkeller in a shock or stress situation, where he might attempt to inhale, could fill his lungs instantly with water. While having these advantages snorkel air inlet valves present various problems. First of all the said mass of the snorkel air inlet valve, being situated at the air-inlet end of the snorkel has a high level of leverage on the mouth of the snorkeller try ing to hold the said snorkel firmly by the snorkel mouthpiece in his mouth and possibly also by the headband of a pair of goggles. It is therefore essential that the said mass of the snorkel air inlet valve be minimised. For the same problem of the said leverage on the mouth of the snorkeller and possibly on the said headband of a pair of goggles, the said snorkel air inlet valve must also be small in order to reduce its drag when submerged in water.

A second problem of snorkel air inlet valves, as mentioned above, is that of tilt. A said snorkel air inlet valve becomes less responsive with tilt towards the horizontal plane, up to the point where it, at and beyond the horizontal plane, completely ceases to function, thus limiting the manoeuvrability of a snorkeller trying to avoid flooding of his snorkel, when on or below the surface of the water.

A third problem of the above mentioned snorkel air inlet valve is that of premature activation or premature deactivation. Because the said snorkel air inlet valve is limited in size and mass, for reasons explained above, the above mentioned float can offer only a small level of force for the activation of the said snorkel air inlet valve, thus making the said snorkel air inlet valve highly sensitive. This above mentioned high level of sensitivity of the said snorkel air inlet valve presents the problem that the said snorkel air inlet valve may also be activated or deactivated by forces other than that of floatation such as air flow, air pressure, water flow or water pressure.

A forth problem of the above mentioned snorkel air inlet valve is that of a snorkeller using a snorkel with a water outlet valve situated under the lowest section of the said snorkel when in an upright position with the air inlet end of the snorkel pointing upwards, used to discharge water that has managed to find its way into the said snorkel. The said snorkeller will require a means, at will, to forcefully close the said snorkel air inlet valve so that by strong exhalation a pressure can be built up within the said snorkel, which will force water resting in the water-outlet valve end of the said snorkel, out of the said snorkel via the said water outlet valve.

The invention seeks to provide a snorkel air inlet valve of the above-mentioned kind, which is small and compact, which will automatically close and stay closed when tilted to and beyond an angle of tilt where the floatation of the float alone would ceases to effect closure, and which will not be prematurely activated or deactivated by inhalation, exhalation or by the flow or pressure of water in which it submerges, which, when the snorkeller blows sharply into the snorkel, closes in order to allow a pressure in the snorkel to build up and press water, collected in the snorkel, out through a water outlet valve should there be one. In accordance with the invention, this object is accomplished in a snorkel air inlet valve of the above kind in that the float, having the fonn of a short heavy sectioned pipe and surrounding the snorkel extension pipe, swings loosely in parallel motion back and forwards along the said snorkel extension pipe, pivoted internally on the ends of two horseshoe shaped swing bars, which in turn are pivoted internally further up the ends of the said horseshoe shaped swing bars on the said snorkel extension pipe. The float is slightly denser than water and is partially suspended by a coil-spring wrapped loosely around the said snorkel extension pipe in the gap between the said float and the said snorkel extension pipe. Inside the said snorkel extension pipe is a valve disc pivoted in such a manner that it can be rotated to block the said snorkel extension pipe or to leave it almost completely clear. An arm attached to the said float reaches through a slot in the said snorkel extension pipe to the centre of the said snorkel extension pipe just above the centre of the said valve disc. Pivoted in a lengthways borehole in the centralized end of the said arm is a crank shaped pivot wire, of which the other end fits in a borehole running parallel to the axis of the valve disc in the valve disc, slightly off the axis of the valve disc such that the said valve disc rotates to positions that open and close the passageway in the said snorkel extension pipe as the said float, together with the said arm, swings to and fro along the said snorkel extension pipe. Fixed on the outer end of the said snorkel extension pipe is a flat circular cap. Above the centre of the said valve disc is also a ventilation hole in the side of the said snorkel extension pipe.

A snorkel air inlet valve formed in accordance with the invention has a number of advantages. First of all the float having the form of a short heavy sectioned pipe and encompassing the said snorkel extension pipe minimises its drag when submerged in water and ensures that, regardless of the direction of tilt, when water rises up the said snorkel the said float will always be partially submerged in water and close the said snorkel air inlet valve before the water reaches the said ventilation hole.

The invention has a floatation system that provides two advantages. The said floatation system of the invention is provided by the slightly heavier than water float, which is partially suspended by a coil-spring, which executes a closing motion, meaning it moves along the said snorkel extension pipe in the direction towards the air-inlet end of the said snorkel extension pipe and snorkel air inlet valve combination, when the said float is partially submerged in water because the float is then partially supported by the said water thus reducing the sum of vertical forces downwards on the said float, lightening the load on the said coils-spring supporting the float, which then, partially freed from compressive forces, returns partially to its natural unloaded shape, executing the said closing motion of the float in the process. Since the said closing motion of the said float is activated by a reduction in the said sum of vertical forces downwards on the said float, the said float will also execute the said closing motion when the said snorkel extension pipe is tilted, thus replacing the forces on the said float, which are released on partial submergence in water but lost through tilt, proportionally, so that when the float is at such an angle that it could not execute the closing motion through flotation alone, the force of the said coil-spring takes over and executes the said closing motion ensuring that water can not enter the said snorkel at any angle. The second advantage of the above- mentioned floatation S3^ste is that the said float, being slightly heavier than water, ensures also that the said snorkel air inlet valve remains closed when turned upside down.

The snorkel air inlet valve formed in accordance with the invention has also the following advantages. Since the above-mentioned disc located in the said snorkel extension pipe closes the air-passageway in the said snorkel extension pipe by being rotated about an axis situated centrally along the plane of the said valve disc, air- pressure acting on both sides of the said valve disc is equal when closed and, in combination with the ventilation system of the invention, almost equal when almost open, such that it is not possible for the disc to be prematurely sucked closed but will close when a snorkeller blows hard into his said snorkel / said snorkel air inlet valve combination, which creates high differences in air-velocity and air-pressure within the system, thus providing a snorkeller using a snorkel with a water outlet valve as mentioned above, with a practical means of, spontaneously and without the use of his hands, building up an air-pressure in his snorkel in order to discharge any water re siding there .

A snorkel air inlet valve formed in accordance with the invention has also the advantage that the above-mentioned flat circular cap fixed to the air-inlet end of the said snorkel extension pipe / snorkel air inlet valve combination, acting as a shield, prevents the float, when submerged in water, from being pushed back away from the said closed position by the water, when the snorkel, submerged, is moved backwards, that is in a direction along the axis of the said snorkel air inlet valve towards the air-inlet end of the snorkel air inlet valve, thus opening the said snorkel air inlet valve and letting water enter the said snorkel.

The invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a dissected pictorial view illustrating snorkel air inlet valves in accordance with the invention attached to the air-inlet-end of a snorkel; and

Figure 2 is a dissected pictorial view of the snorkel inlet vent in accordance with the invention.

Figure 1 illustrates a snorkel air inlet valve 11 formed in accordance with the invention, wedged in the snorkel air-inlet-end of the snorkel 13. The snorkel air inlet valve 11 is wedged in the snorkel air-inlet end of the snorkel 13 by means of a ribbed spigot section 45, slightly smaller in diameter than the rest of a snorkel extension pipe 19 of the snorkel air inlet valve 11, and protrudes out of the snorkel air inlet valve 11 and into the end of the snorkel 13 which, with the snorkel 13 being flexible and having a slightly smaller internal diameter than the external diameter of the protruding section of the snorkel extension pipe 19, is firmly gripped. An oversized internal diametef of the snorkel 13 may be corrected by initially wrapping insulation tape around the protruding section of the snorkel extension pipe 19.

Inside and towards the air-inlet-end of the section of the snorkel extension pipe 19, which protrudes out of the snorkel 13, is pivoted a valve disc 21 with a tapered and rounded-off edge, by means of two valve disc pins 27 which are fixed adjacently in the wall of the snorkel extension pipe 19 and protrude inwards into pivot boreholes in the circumference and on a centralised axis of the valve disc 21.

Fixed in the wall of the snorkel extension pipe 19, positioned 90 Degrees to the axis of the valve disc pins 27 when rotated about the axis of the snorkel extension pipe 19, positioned such that it touches the flat outer surface of the valve disc 21 when the valve disc 21 is rotated to the plane perpendicular to the axis of the snorkel air inlet valve, is a valve disc stop pin 25 which protrudes inwards into the snorkel extension pipe 19.

Running partially around the snorkel extension pipe 19 and adjacent to the valve disc stop pin 25 is the edge of a ventilation slot, which opens up towards the air- inlet-end of the snorkel extension pipe 19.

Fixed in and protruding outwards out of the walls of the section of the snorkel extension pipe 19, which protrudes out of the snorkel 13 , are four swing-bar pivot pins 33. Two of the swing-bar pivot pins 33 are positioned adjacent to another on an axis running parallel to the valve disc pins 27 and set slightly off the axis of the valve disc pins 27 in the direction away from the valve disc stop pin 25. The other two sing-bar pivot pins 33 are located in the snorkel 13 end of the section of the snorkel extension pipe 19, which protrudes out of the snorkel 13, adjacent to another on an axis which passes through the axis of the snorkel extension pipe 19 and runs parallel to the axis of the valve disc pins 27.

Two identical horseshow shaped swing bars 37 and 39, which are both made up of two straight sections that protrude from the ends of a semicircle section, are pivoted on the swing-bar pivot pins 33, which protrude out of the snorkel extension pipe 19 and into pivot boreholes of restricting depth located in the inner sides of the said semicircle end of the said straight sections of the horseshoe shaped swing bars 37 and 39. Horseshow shaped swing bar 39 is pivoted on swing-bar pivot pins 33, which are located slightly off the axis of the valve disc pins 27, such that the said straight sections of the horseshow shaped swing bar 39 point in the direction of the valve disc stop pin 25. Horseshow shaped swing bar 37 is pivoted on the other two pivot pins 33 located in the snorkel 13 end of the section of the snorkel extension pipe 19 which protrudes out of the snorkel 13, parallel to and in the same manner as horseshow shaped swing bar 39.

A float 17 has the form of a short heavy sectioned pipe made up of two sections different in length and internal diameter. The said longer section of the float 17 has a smaller internal diameter than that of the said shorter section of the float 17.

Two short parallel channels cut in the inner surface of the section of the float 17 having the smaller internal diameter, starting from the end of the float 17 having the smaller internal diameter, are such that horseshow shaped swing bar 37 could now pass, without making contact with the float 17, with the plane of horseshow shaped swing bar 37 being perpendicular to the axis of the float 17, into the end of the float 17 having the smaller internal diameter, with the free ends of the straight sections of swing bar 37 passing into the said two short parallel channels cut in the inner surface of the float.

Protruding out of the inner end of the said section of the float 17 with the smaller inner diameter and reaching almost to the open end of the float 17 with the said larger inner diameter, are two wedge formed bushes 41 with rectangle-triangle cross-sections of which one rectangular side of each of the wedge formed bushes 41 is identical to and on the same plane and longitudinal line running parallel to the axis of the float 17, as each of the outermost inner side of the two said short parallel channels cut in the inner surface of the float 17 respectively. The larger rectangular sides of the wedge formed bushes 41 fuse with the inner surface of the float 17.

Fixed in and protruding perpendicularly out of the centre of each of the said outermost inner sides of the two short parallel channels cut in the inner surface of the float 17 is a float pivot pin 35 respectively. Fixed in and protruding perpendicularly out of each of the sides of the two wedge formed bushes 41 which are on the same plane as the said outermost inner sides of the two short parallel channels cut in the inner surface of the float 17, is a float pivot pin 35 respectively.

The open ends of the four float pivot pins 35 fit with freedom to rotate in boreholes of restricting depth on axis parallel to that of the valve disc pins 27, in the outer surface of each of the in total four ends of the two horseshow shaped swing bars 37 and 39 such that float 17 can swing parallel to and with parallel motion to the snorkel extension pipe 19 on the ends of the two horseshow shaped swing bars 37 and 39 which in turn can rotate about the four swing-bar pivot pins 33 fixed in the snorkel extension pipe 19, with the end of the float 17 with the smallest internal diameter facing the ribbed end of the snorkel extension pipe 19. One straight section of an L-shaped bridging bush bar 29 protrudes out of the inner end of the section of the float 17 with the smallest internal diameter along an axis parallel to that of the float 17. The other straight section of the L-shaped bridging bush bar 29 follows an axis parallel to that of the valve disc pins 27 and reaches just through a short slot, which is in the wall of the snorkel extension pipe 19 and longitudinal to the snorkel extension pipe 19 and starts at a point which is just off the axis of the valve disc pins 27 in the direction towards the valve disc stop pin and on the plane of the valve disc stop pin 25 perpendicular to the axis of the snorkel extension pipe 19.

A crank wire 23, which has the same basic form as a starting handle of the engine of a car, with the exception that the middle section is bent at 90 Degrees in the middle along a plane perpendicular to axis of the end sections of the crank wire 23. One end of the crank wire 23 is located, with freedom to rotate, in a borehole of restricting depth in and running along the central axis of the open-ended straight section of the L-shaped bridging bush bar 29. The other end of the crank wire 23 is located, with freedom to rotate, in a shallow borehole on an axis parallel to and just off the axis of the valve disc pins 27 and situated deep in the innermost side of a short shallow channel cut in a flat surface of the valve disc 21 , which starts on the axis of the valve discs pin 21 close to the side of the bridging bush bar 29 and follows a line perpendicular to the valve disc pins 21 towards the valve disc stop pin 25 when the valve disc 21 is in the position that closes the snorkel extension pipe 19, such that as float 17 swings to and fro the end of the L-shaped bridging bush bar 29 follows the same motion in the slot inside the snorkel extension pipe 19 and moves the crank wire 23 to and fro which in turn rotates the valve disc 21 to angles that leave the snorkel extension pipe open or closed.

A spring clearance section 9 of snorkel extension pipe 19 between the two horseshow shaped swing bars 37 and 39 has a smaller external diameter than the bordering sections of the snorkel extension pipe 19 and the axis of external diameter of the clearance section 9 is centred off the axis of the snorkel extension pipe 19 such that the wall thickness of the spring clearance section 9 on the side of snorkel extension pipe 19 with the valve stop pin 25 is equal to that of the bordering sections of snorkel extension pipe 19 to the clearance section 9.

One end of a single loop spiral spring 31 , having a diameter lying between that of the outer diameter of the spring clearance section 9 and the smallest internal diameter of the float 17, is bent outwards pointing away from the centre of spiral spring 13 and threaded through a borehole going right through the wall of the float 17, at a point midway between the four float pivot pins 35, and is bent over 90 Degrees into a short narrow slot running lengthways in the outer surface of the float 17 thus fixing that end of the spiral spring 13 so that it can neither be moved nor rotated. The other end of the spiral spring 31 is bent inwards pointing towards and on an axis perpendicular to the axis of the snorkel extension pipe 19 and is located with freedom to rotate in a borehole of restricting depth in the snorkel extension pipe 19 at a position virtually across from the external end of the spiral spring 31 placing the spiral spring 31 in a state of compression such that the forces of expansion of the spiral spring 31 act on the float 17 along an axis parallel to the axis of the float in a direction towards the air inlet end of the snorkel extension pipe 19.

A thin walled cap 15 with an external diameter equal to that of the float 17 is fixed to the air inlet end of the snorkel extension pipe 19 by means of an internal centralized stump 43 which is partially hollowed out and fixed tightly inside the snorkel extension pipe 19 by means of either a thread, sprung catch sections or bridging pins. The rim of the thin walled cap 15 that protrudes parallel to the axis of the float 17, towards the float 17, almost reaches float 17 when float 17 is in a position which leaves the passageway within the snorkel extension pipe 19 closed.

Claims

1. A snorkel air inlet valve (11) comprising a valve disc (21) pivoted along a centralized axis along the plane of said valve disc (21) fitting perfectly inside a snorkel extension pipe (19), a crank wire (23) of which one end is pivoted at an off- centre point in a flat side of the said valve disc (21 ), an L-shaped bridging bush bar (29) in one end thereof is the other end of the said crank wire (23) pivoted, a float (17) surrounding a section of the said snorkel extension pipe (19) adjacent to a ribbed spigot section (45) and attached thereto is the other end of the said L-shaped bridging bush bar (29), horseshow shaped swing bar (37, 39) parallel to another and spaced from another along the said snorkel pipe (19) and encircling approximately 180 degrees of the said snorkel extension pipe (19) and pivoted to the said snorkel pipe (19) at points where the straight and curve sections of the horseshow shaped swing bar (37, 39) join and pivoted to the ends thereof is the said float (17) surrounding the said horseshow shaped swing bar (37, 38) such that the said float can swing parallel and in parallel motion along the said snorkel extension pipe, single loop spiral spring (31) encircling a section (9) of the said snorkel extension pipe 1 between the said two horseshow shaped swing bars (37, 39) and is attached at one end to the said snorkel extension pipe ( 19) and attached at the other end to the said float (17), a thin walled cap (15) attached to the end of the said snorkel extension pipe (19) by means of a internally centralized stump (43), a valve disc stop pin (25) mounted in and protruding inwards from the wall of the said snorkel extension pipe (19) such that the said valve disc stop pin (25) prevents the said valve disc (21) from being pulled by the said crank wire (23) through the angle at which the said snorkel extension pipe (19) is closed, a ventilation slot (7) in the side of the snorkel extension pipe (19) and between the valve disc (21 ) and the thin walled cap (15) and positioned on the opposite side of the axis of the said disc vent (21 ) to that of the said crank wire (23), a said ribbed spigot section (45) of the said snorkel extension pipe (19) protruding out from the said float (17), characterised in that the said ribbed spigot section (45) with or without the use of insulating tape mates tightly with the air inlet end of a snorkel or is an air inlet end section of a snorkel.

2. A snorkel air inlet valve as claimed in Claim 1 , characterised in that said horseshoe shaped swing bars (37, 39) located parallel to another and spaced from another along the said snorkel pipe (19) and encircling 180 degrees of the said snorkel extension pipe (19) and pivoted to the said snorkel pipe (19) at the points where the straight and curve sections of the said horseshow shaped swing bar (37, 39) join and pivoted to the ends thereof is the said float (17) surrounding the said horseshow shaped swing bar (37, 38) such that the said float can swing parallel and in parallel motion to and fro along the said snorkel extension pipe (19).

3. A snorkel air inlet valve as claimed in Claim 2, characterised in that said valve disc (21 ) is pivoted along an axis centralized along the plane of said valve disc (21) and fits perfectly inside said snorkel extension pipe (19) and is adjusted in pitch by the said crank wire (23) of which one end is pivoted at an off-axis point of the said valve disc (21) in a flat side of the said valve disc (21) and the other end of the said crank wire (23) is pivoted in an end of the said L-shaped bridging bush bar (29) attached to the said float (17).

4. A snorkel air inlet valve as claimed in Claim 3, characterised in that said crank wire (23) has the same basic form as a starting handle of the engine of a car, with the exception that the middle section is bent at an angle along a plane perpendicular to axis of end sections of the said crank wire (23).

5. A snorkel air inlet valve as claimed in Claim 4, characterised in that said ventilation slot (7) is positioned in the side of the snorkel extension pipe (19) and between the valve disc (21) and the thin walled cap (15) and on the opposite side of the axis of the said disc vent (21 ) to that of the said crank wire (23).

6. A snorkel air inlet valve as claimed in Claim 5, characterised in that said float ( 17) is subj ected to the force of a said single loop spiral spring (31) which encircles a section of the said snorkel extension pipe 19 between the said two horseshow shaped swing bars (37, 39) and is attached at one end to the said snorkel extension pipe (19) and attached at the other end to the said float (17) such that the said float (17) is subject to the expansive force of the said single loop spiral spring (31) acting in a direction away from the said ribbed spigot section (45) end of the said snorkel extension pipe (19).

7. A snorkel air inlet valve as claimed in Claim 6, characterised in that said float (17) is made of a material that has a density equal to or greater than the average density of surface water.

8. A snorkel air inlet valve as claimed in Claim 7, characterised in that said float (17) comprises section (3) and section (5) of which said section (3) has a smaller internal diameter than section (5) and is situated between the said ribbed spigot section (45) and axis of the said disc valve (21).

9. A snorkel air inlet valve as claimed in Claim 8, characterised in that said disc valve stop pin (25) protrudes inwards from the wall of the snorkel extension pipe (19) such that said disc valve (21) is prevented from rotating through an angle at which the said snorkel extension pipe (19) is completely blocked by the said disc valve (21).

10. A snorkel air inlet valve as claimed in Claim 9, characterised in that said thin walled cap (15) is attached to the air inlet end of the said snorkel extension pipe (19) and is of the same external diameter as that of the said float (17), and in that the rim of the said thin walled cap (15) protrudes towards and almost touches the outer edge of section (5) of the said float (17) when said float (17) reaches a position where the disc valve completely blocks the passage through the said snorkel extension pipe (19).

11. A snorkel air inlet valve as claimed in Claim 10, characterised in that said thin walled cap (15) is attached to the air inlet end of the said snorkel extension pipe (19) by means of a said internally centralized stump (43).

12. A snorkel air Met valve as claimed in Claim 1 1, characterised in that when the angle between the plane of the said vent disc (21) and the axis of the said snorkel extension pipe ( 19) reaches a minimum, the outer edge of said vent disc (21 ) in the air inlet end of the said snorkel extension pipe (19), almost touches the either flat or hollowed out inner surface of the said internally centralized stump (43) such that a partial air lock is created on the side of the said valve disc (21 ) of the said crank wire (23).