NZ260914A - Control vlalve with internal member separating two fluids one of which is above atmospheric pressure - Google Patents

Description

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Patents Act 1953 .&L Number: 2 60914 Date: 25 October 1990 COMPLETE SPECIFICATION AN IMPROVED CONTROL VALVE I, DAVID JOHN PICTON, a British citizen of 356 Point View Drive, R.D. 1, Papatoetoe, Auckland, New Zealand, hereby declare the invention for which I pray that a patent may be granted to me and the method by which it is to be \ performed, to be particularly described in and by the following statement:- 26 0 9 1 4 RACltnRniTMD OF THE IWVEHTIOW This invention relates to an improved control valve for a fire alarm system and associated fire extinguishing system which preferably uses water as the extinguishant.

In the past sprinkler systems used to control the spread of fire have required the use of steel or other pipes of various diameters to which were fitted heat sensitive sprinkler heads. In most cases the pipes are at all times full of water, so that when one of the sprinkler heads is activated there is an immediate flow of water through the activated sprinkler head. This water acts to control the spread of fire.

Such conventional fire sprinkler systems have disadvantages. First of all steel pipes are costly and are relatively expensive to install in terms of labour time. Secondly, pipes holding water are subject to deterioration at a significantly greater rate than dry-pipes. Thirdly, there can be difficulties with bacterial or other organisms which grow in the static body of water contained within the pipes. This can necessitate having to flush the system out periodically. The main disadvantage, however, is the cost and the result is that ^ many buildings which ought to be protected, such as *k \ school buildings, domestic dwellings, small shops, halls ^ etc. , are not protected because these installation co'$1^ftV >.

J* l^ -.. are thought to be excessive. Furthermore, the prim,e neejl V / ~2~ ^ ' 260 9 14 of any fire protection system is to detect the fire and activate an alarm. This warns people to escape and/or allows or causes the summoning of appropriate assistance e.g. a fire brigade. It is advantageous but not always essential that the system then causes the fire to be extinguished or controlled. It is desirable to have extensive heat sensors.

BRIEF SUMMARY OF THE INVENTION The present invention consists in a control valve comprising first and second chambers, an outlet in the second chamber and an inlet in the first chamber a movable member having first and second ends, and first and second sealing means adapted to seal against the movable member, the second sealing means enclosing a larger area than the first sealing means, the construction and arrangement being such that in use a first fluid supply introduced into the first chamber via the inlet is normally prevented from leaving it by the said first end of said movable member and the first said sealing means, while a second fluid supply introduced into the second chamber is normally prevented from leaving it by the second end of the said movable member and the second said sealing means, respective areas enclosed by the sealing means being such that the forces which may be exerted by gravity and are exerted by the pressure of the respective fluid supplies on the movable */} -O. member are unbalanced causing the movable member to, f-\ fe- v\ ; % t 3 - ^ / 4 260 9 14 remain in a "closed" position except when the second fluid supply pressure falls close enough to atmospheric pressure the movable member is caused to be moved within the second chamber by an opposite imbalance in forces acting on it to such an extent that the sealing means cease to seal and the first fluid can flow from the inlet into the second chamber and thence, through the outlet.

BRTEF DESCRIPTION OF THE DRAWINGS A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is an example of a schematic layout of a fire alarm system which is adapted to use a control valve according to the present invention.

Fig. 2 is a schematic central cross-sectional view of a control valve of the present invention.

Fig.- 3 is a schematic central cross-sectional view of an alternative control valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT V \ The present invention is to be used with a fire alarm ^1*; system including as a primary heat sensor a ... tiar'X thermoplastics pipe 61 preferably forming part of ^glpe ; % a- -4- i' ' a*/ I 260 9 1 4 network 53, preferably constructed of 16 millimeter internal diameter polypropylene, or perhaps polybutylene or polyethylene pipe, with preferably uniquely coloured and dimensioned plastics fittings such as T fittings, elbows and the like. The pipe and fittings are typically coloured red, to identify them as belonging to the fire alarm/control and the pipe diameter is chosen to be sufficiently large so that the pipe can carry an effective amount of extinguishant to enable a fire to be quenched. This pipework is usually installed in the under roof above ceiling space of premises to be protected, and may include droppers 55 to secondary sensors preferably in the form of sprinkler heads 56 located belo"* the ceiling of the premises. The sprinkler heads may be of the usual variety, with a fluid-filled glass bulb where the fluid, on expansion caused by excessive heat, fractures the bulb to allow the sprinkler head to open and to sprinkle any extinguishant which may be supplied via the pipe network 53. However, any suitable device, activated by heat, smoke or fire, to open a valve or nozzle, may be used as a secondary heat sensor.

The primary heat sensors are the pipes of the network 53. The pipe 54 itself can function as a heat sensor as it will soften under excessive heat to rupture under the pressure of a gas (usually air) arranged to be within the pipe network at above atmospheric pressure (typically at 60 psi or about 4 MPa). When the pipe ruptures the gas 260 9 1 4 within escapes and the gas pressure within the network falls. Detection means 10 detects when the gas pressure falls to a first predetermined level or pressure and thereupon causes activation of a first alarm means 59 which may be audible and/or visible, internal and/or external of the premises to be protected and/or which may activate telephone dialing means to transmit the alarm to a distant location.

The pipe network 53 communicates with a control means 62 which includes an automatic valve which is connected via a T-joint 57 to a main liquid supply line 58. The valve (Fig. 2) has an inlet 12' and an outlet 14'. The inlet 12' communicates with a first chamber 15' within a 2 part housings 27', 29'. A second chamber 17' communicates with the outlet 14' and with the first chamber 15'.

Within these chambers there is a movable member 20' which may be in the form of a plate or a piston, for example, having a first end 63' and a second end 64'.

First and second sealing means adapted to seal against the movable member may comprise "O" rings 25' and 65' respectively with the second sealing means 65' enclosing a larger area than the first sealing means and enclosing the first sealing means. This is to provide an hydraulic multiplier effect when the movable member 20' is subjected to different fluid forces on opposite ends 63' and 64'. 260 9 1 4 The outlet port 14' is preferably located above the second chamber 17'. A pipe such as 34 (Fig. 1) may be secured to the outlet 14'.

Preferably, the housing of the valve is formed in two parts 27', 29'. The upper part 29' may be removable to enable the movable member 20' to be installed or removed for service.

In normal use the pipe network 53 is pumped up with air. A pressure gauge or monitor 40 (Figures 1 and 3) located anywhere in the pipe system or on the control valve 62, indicates when there is sufficient air pressure in the pipes. The air pressure on the second end 64' of the movable member 20' ensures that it is pressed downwardly as far as it can travel within the second chamber 17' so that the first end 63' blocks the ingress of water supplied to the inlet 12' into the second chamber 17'. However, when the air pressure falls sufficiently, such as is caused by a fracture of a sprinkler head bulb or a melted pipe, then the force exerted by the water supply exceeds the downward force exerted by air pressure and the weight of the movable member 20' and the first and second sealing means 25' and 65' cease to seal. By this means water quickly floods the pipe network and flows out any activated sprinkler head or heads.

Preferably, a vacuum release port 47' or valve is provided to allow air into the space 49' between the 260 9 14 movable member 20' and the housing 27' . It also allows any gas which might pass the second sealing means 65' to escape and not contaminate the water supplied to the inlet 12'.

When the valve is to be installed, a tap (not shown) which may be supplied as part of the control means 62 immediately upstream of the inlet 12', prevents water from reaching the valve. The pipes downstream of the valve are inflated, and checked after a period (preferably at least twenty-four hours) to ensure that the system is not leaking. Only after this check has been made is the tap turned on to allow water into the inlet 12', and to render the system operational.

Associated with the system are suitable alarm means 59. A first or main fire alarm is provided, which is activated when there is a sudden drop in, or a complete loss of, air pressure say to 15 psi or about 0.1 MPa or less. This may be a high volume audible alarm. The alarm may be activated by detection means 10 which detect when the gas pressure within the network falls to a first predetermined level. For example, the detection means may comprise a pressure switch 42, (Fig. 3) communicating with the valve outlet 14 via a port 43 and connected to the alarm via wires 44. The alarm may comprise or include flashing lights, or means to dial a telephone to call the fire brigade or alert a computer, or any combination or these and similar devices. As well the 26o y 1 4 first alarm system may be actuable from bedside or doorside panic buttons in a domestic situation or by excessive heat in the usual hot water cylinder. Extreme heat can lead to serious scalding and sometimes violent explosion of the cylinder. Then a complete domestic warning system can easily be integrated into the alarm means.

A second alarm means may be provided to operate when the system is in need of servicing. This could be set to activate when the air pressure drops to, say, 30 psi, or about 0.2 MPa to indicate the need to recharge the system with air, or if any battery supplying energy to any electronic circuit associated with the alarm runs low. This alarm may, for instance, be a low volume audible alarm.

Among the advantages of the present invention are its cheapness and ease of installation, and also the additional safety factor against flooding given by eliminating or at least restricting the use of overhead water-filled pipes.

Many variations to the above may be made. For example, the pipes in the network may be of any suitable size and configuration, and may be made of any suitable material, such as polybutylene or any other suitable plastics, and some may be made of metal. Polyethylene can be suitable for pipes of small diameter. Other forms of control 26 0 9 valve could be used to achieve the same effect as the valve described, with water.

Any other suitable gas could be used instead of air to pressurize the pipe network and hold the control valve closed. For special situations extinguishants such as gas, e.g. carbon dioxide, may comprise the extinguishant supply instead of water.

A preferred control means valve is shown in Fig. 3 where the reference numerals are where possible identical to those used in Fig. 2 minus the dashes.

Typically, the two housing parts 27 and 29 are bolted together by a number of bolts (such as 31) around the mating flanges and sealed, such as with an O-ring 33. Instead of bolts 31 to hold the valve housing together, band clamping may be used. This involves encircling the joint with a metal band, and then clamping or folding over the edges of the band to crimp it into place, securing the housing together.

There is also a gas inlet valve 37 which lies forward of the cross-sectional view and would thus not normally be shown but is illustrated with coacting steps 45 for convenience. It is preferably a tyre valve or similar, in the upper housing 29, although it could be provided anywhere in the pipe network 53 if that should be more convenient. The internal end 38 of the valve 37 may 260 9 14 typically be a hexagonal head seated in a hexagonal recess formed by steps or wall 45, so that the valve can readily be secured in place with a nut 68, without rotating as the nut is being tightened. The valve also has its own O-ring 52 at the internal end 38 to enable it to be tightened sealingly in place. The gas inlet valve alternatively could be provided as part of the screw-in base 59 of the pressure gauge 40.

The movable member of Fig. 3 is a piston 20 which may be popped out of the first small diameter cylindrical chamber 15 and a second cylindrically walled chamber 17 to lie within a third chamber 39 in the upper housing 29. The third chamber 3 9 is conveniently of a greater diameter than the piston 20, and sufficiently large that the piston 20 fits loosely within it, with ample space for water to flow around it and through the outlet 14. The steps or walls 45 may form one or more means to prevent the piston from closing the outlet 14.

At the center of the piston there is a small hexagonal hole 51, arranged to receive the end of a hexagonal Allen key wrench. When the piston has been popped out of its cylinders 15 and 17, it must be replaced before the valve is ready for use again. The arm of the Allen key can be passed down the outlet 14 to engage the socket 51, and manoeuvre the piston back into its cylinder after uncoupling the outer pipe 34 by releasing the nut 36. 260 9 1 4 When a valve of the present invention has been manufactured, and must be shipped to a location where it is to be used, it would be preferable that the piston not fall or be knocked out of the cylinders into the chamber 39. To prevent this, a temporary cap (not shown) may be screwed onto the threaded end of the outlet 14. A rod or finger from the center of the cap extends into the valve and engages the socket 51, to hold the piston securely in place.

Claims (8)

260 9 WHAT I CLAIM IS:

1. A control valve comprising first and second chambers, an outlet in the second chamber and an inlet in the first chamber, an internal movable member having first and second ends, and first and second sealing means adapted to seal against the movable member, the second sealing means enclosing a larger area than the first sealing means, the construction and arrangement being such that in use a first fluid supply introduced into the first chamber via the inlet is normally prevented from leaving it by the said first end of said movable member and the first said sealing means, while a second fluid supply introduced into the second chamber is normally prevented from leaving it by the second end of the said movable member and the second said sealing means, respective areas enclosed by the sealing means being such that the forces which may be exerted by gravity and are exerted by the pressure of the respective fluid supplies on the movable member are imbalanced causing the movable member to remain in a "closed" position except when the second fluid supply pressure falls close enough to atmospheric pressure the movable member is caused to be moved within the second chamber by an opposite imbalance in forces acting on it to such an extent that the sealing means cease to seal and the first fluid can flow from the inlet into the second chamber and thence, through the outlet. -13- 26 0 9 1 4

2. A control valve comprising an inlet and an outlet, first and second cylindrically walled chambers, the first chamber being of a smaller diameter than the second chamber, and an internal stepped piston having first and second portions, the first portion being smaller in diameter than the second portion, the portions of the piston normally being located in a "closed" position within the first and second chambers respectively, and the first and second sealing means between said respective first and second portions and said chambers, the construction and arrangement being such that if a first fluid supply is introduced via the inlet into the first chamber at above atmospheric pressure it is normally prevented from leaving it by the said first portion of said piston and said first sealing means, while if a second fluid supply is introduced at above atmospheric pressure into the second chamber it is normally prevented from leaving it by the second portion of the said piston and said second sealing means, the imbalance between the forces exerted by gravity and the pressure of the first and second fluid supplies on the piston causing the piston to remain in the "closed" position, except when the second fluid pressure falls close enough to atmospheric pressure the piston is able to be moved by the now oppositely imbalanced forces acting on it, within its chambers to such an extent that the first portion of the piston is ejected by liquid pressure -14- 260 9 1 4 out of the first chamber so that the liquid can flow from the first chamber into the second chamber and thence to the outlet in said second chamber.

3. A control valve as claimed in claim 2 wherein the valve includes a third chamber between the said second chamber and the outlet, larger in diameter than the second chamber, within which the piston may be positioned during flow of first fluid through the second chamber.

4. A control valve as claimed in either one of claims 2 or 3 wherein the valve includes a vacuum release port between first and second sealing means to prevent the piston being held closed by vacuum.

5. A control valve as claimed in any one of claims 1 to 4 wherein the valve includes a pressure sensing means on the outlet side of the valve.

6. A control valve as claimed in any one of claims 1 to 5 wherein the valve comprises a housing formed in two parts, separable when required, to permit access to the chambers.

7. A control valve as claimed in any one of claims 1 to 6 wherein there is a gas inlet valve on the outlet side of the valve. -15- 260 9 14

8. A control valve substantially as herein described with reference to Fig. 2 of the accompanying drawings. DAVID JOHN PICTON By his authorised agents, -16-