US3788400A

US3788400A - Fire extinguishing system and valve for use therewith

Info

Publication number: US3788400A
Application number: US00357924A
Authority: US
Inventors: H Tufts
Original assignee: Pyrotector Inc
Current assignee: Kidde Technologies Inc; Graviner Inc
Priority date: 1973-05-07
Filing date: 1973-05-07
Publication date: 1974-01-29
Anticipated expiration: 1991-01-29
Also published as: FR2228502B1; BR7403694D0; JPS544559B2; IT1013984B; AU6554274A; IL44112A; CH566792A5; AU497018B2; DE2416673A1; IL44112A0; FR2228502A1; GB1471952A; GB1471951A; JPS5015398A; IN141140B; AR200430A1; CA996092A; NL7403710A; ZA74811B; SE393300B

Abstract

A fire extinguishing system and a valve for use therein, said system having both automatic and manual means for actuating the valve, said valve being designed for use in systems utilizing vaporizable extinguishants maintained under high pressure, and to give a very fast rate of extinguishant release, to allow the system to be used in applications where explosion suppression is desired. The valve is of the type utilizing a main valve and a pilot valve, in which the pilot valve is arranged to actuate the main valve by releasing the pressure on the back side thereof. In one embodiment of the invention pressure is supplied to the back side of the main valve piston only by leakage past the periphery of the piston. The pressure on the back side of the piston is released by the pilot valve to atmosphere rather than into the discharge line to avoid possible interference with said pressure release due to pressure buildup in the main discharge line. The pilot valve may be actuated by either a solenoid or mechanically by means contacting the face of the pilot valve covering the pilot valve discharge line, thereby avoiding sealing problems ordinarily encountered with such mechanical actuating means.

Description

United States Patent [1 1 Tufts [111 3,788,400 ['45] Jan. 29, 1974 FIRE EXTINGUISHING SYSTEM AND VALVE FOR USE THEREWITH [75] Inventor: Howard L. Tufts, Hingham, Mass.

[52] US. Cl 169/11, 169/22, 251/62 [51] Int. Cl. A62c 37/08 [58] Field of Search... 169/5, 11, 19, 20, 22; 251/62 [56] References Cited UNITED STATES PATENTS 9/1962 Williamson et al.... 169/11 11/1965 Hoevenaar 169/5 X Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Michael Y. Mar Attorney, Agent, or FirmRobert E. Ross [57] ABSTRACT A fire extinguishing system and a valve for use therein,

said system having both automatic and manual means for actuating the valve, said valve being designed for use in systems utilizing vaporizable extinguishants maintained under high pressure, and to give a very fast rate of extinguishant release, to allow the system to be used in applications where explosion suppression is desired. The valve is of the type utilizing a main valve and a pilot valve, in which the pilot valve is arranged to actuate the main valve by releasing the pressure on the back side thereof. In one embodiment of the invention pressure is supplied to the back side of the main valve piston only by leakage past the periphery of the piston. The pressure on the back side of the piston is released by the pilot valve to atmosphere rather than into the discharge line to avoid possible interference with said pressure release due to pressure buildup in the main discharge line. The pilot valve may be actuated by either a solenoid or mechanically by means contacting the face of the pilot valve covering the pilot valve discharge line, thereby avoiding sealing problems ordinarily encountered with such mechanical actuating means.

6 Claims, 3 Drawing Figures FIRE EXTINGUISI'IING SYSTEM AND VALVE FOR USE THEREWITH BACKGROUND OF THE INVENTION Certain types of fire extinguishing systems utilize a container pressurized with a liquid extinguishant material and a discharge valve connected to the container, with means for automatically actuating said valve on the detection of a fire, to release the extinguishant to discharge nozzles.

To achieve rapid release of the extinguishant on the receipt of a signal from the fire detecting device, a very fast acting valve is required, particularly in installations where the system is expected to act as explosion supression means.

In such extinguishing systems it is customary to use a squib operated valve to achieve fast actuation, if the system is to be used as an explosion suppression system. If not, a valve operated by a solenoid operated pilot valve may be used. In this latter type of valve, a main piston is pressurized on both sides by the extinguishant, and maintained closed by the differential force resulting from the larger pressurized area on the back of the piston. The opening of a pilot valve releases the pressure from the back side of the piston into the discharge line, so that the pressure on the front side of the piston is utilized to open the valve.

However commercially available valves of this type have been found to be inoperative when used with new types of extinguishants now available, apparently because of the high liquid to vapor expansion ration of such materials, and the pressure at which they are stored. For example, a new extinguishant known commercially as Halon 1301, manufactured by E.I. du Pont de Nemours Company of Wilmington, Delaware, has an expansion ratio of about 250 to l and is normally stored at a pressure of about 600 p.s.i. When a material of this type is used with a valve of the type described above, the valve does not operate satisfactorily to release the extinguishant at an adequate rate, due to valve chattering. This is apparently caused by the fact that when the valve is opened, the liquid extinguishant passing through the valve into the piping leading to the discharge nozzles builds up sufficient pressure at the valve outlet to cause liquid extinguishant to back up into the chamber on the back side of the valve through the pilot valve discharge line. This causes the pressure to again build up behind the main piston, forcing it closed. The problem is increased by the fact that liquid extinguishant also flows into the chamber on the back side of the valve through bleed or pressure equalizing orifices in the piston. The result is valve chatter that reduces the rate of discharge of the extinguishant and renders the system ineffective for its intended purpose.

Another problem with such valves is the fact that even if the chatter problem is eliminated in some manner, the speed of operation of the valve is not great enough to allow it to be used in an explosion suppression system. The speed of operation of the valve is apparently affected by the fact that when pressure is released from the chamber on the back side of the piston, pressurized extinguishant from the front side of the piston (supplied directly from the pressurized container) passes through bleed holes in the piston and effectively reduces the rate at which the pressure behind the piston can drop. Hence, for use in explosion suppression systems, it has been necessary to use squib-operated valves, which are susceptible to false firing and cannot have multiple firing capability.

A further problem with such valves is the fact that although means has been provided for mechanically opening the valve to allow for manual firing of the system, such means has required a high operating force to overcome the force holding the valve closed, and therefore the mechanical advantage required for manual operation has ruled out the use of a simple pull cable operated from a distant control panel.

SUMMARY OF THE INVENTION In accordance with this invention a fire extinguishing system utilizes a valve in which a pilot valve discharge port opens to the atmosphere rather than into the main discharge line, thereby preventing pressure in the discharge line after valve actuation from interfering with flow out of the pilot valve. Means is also provided for restricting the rate of flow of liquid extinguishant into the space behind the main piston to an amount less than the rate at which vaporized extinguishant can flow out of the pilot valve. Means is also provided for mechanically unseating the pilot valve by means in the pilot valve discharge line pushing against the unpressurized face of the pilot valve covering the pilot valve discharge opening.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a view in section of a valve embodying the features of the invention.

FIG. 2 is an enlarged view of a portion of the valve of FIG. 1, illustrating the means for mechanically operating the pilot valve.

FIG. 3 is a schematic view of a fire detection and suppression system utilizing the valve of FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring to FIG. 3 of the drawing, there is illustrated a fire extinguishing system which comprises a bottle 10 containing a fire extinguishing medium under pressure, a valve 12 attached to the bottle, and a main discharge line 14 leading to a series of discharge nozzles 16.

The valve 12 may be either manually actuated by a lever 18 or electrically actuated by a solenoid 20 to release the extinguishant from the bottle to the nozzle 16, in a manner to appear hereinafter. Electrical actuation may be as a result of one or more of a plurality of detector units 22 actuating an amplifier 24 in response to radiation from a fire.

The valve 12 comprises a housing 26 with inlet and

outlet

28 and 30, an internal valve seat 32, a cylinder 34 formed above the seat, and a piston 36 slidable in the cylinder into and out engagement with the seat 32.

A chamber 33 is disposed above the piston, and during standby operation of the fire detector system, the full bottle pressure exists on both sides of the piston by means to be described hereinafter, so that the piston, during such standby conditions, is forced tightly against the valve seat due to the greater pressurized area on the top of the piston. A biasing spring 40 is provided between the piston and the upper portion of the housing to start the piston to the closed position after the valve has been operated.

The valve is actuated by releasing the pressure from the chamber 36 by means of a pilot valve plunger 42 disposed in a housing 44. The housing 44 opens to the chamber 38 so that the plunger 42 is surrounded by the chamber pressure. Spring 46 biases the plunger down onto a seat 48, which opens to a pilot valve discharge line 50 having a port 52 to atmosphere.

Mounted on the upper end of the housing 44 is the solenoid 20. Energization of the solenoid causes the plunger 42 to move upwardly, opening the chamber 38 to the atmosphere.

The pilot valve plunger 42 may also be lifted off its seat by the lever 18 in a manner now to be described. Disposed at the bottom of the discharge line below the port 52 is a camshaft 54 rotatable by the lever 18 having a cam surface 56 formed thereon. Resting on the cam surface 56 is a cam follower 58 which is movable vertically with rotation of the cam shaft by the lever 18. Protruding upwardly from the cam follower is a pin 60 which extends into the pilot valve seat opening and contacts the bottom of the portion of the pilot valve covering the opening. Rotation of the camshaft by the lever moves the cam follower 58 and pin 60 upwardly pushing the pilot valve plunger 42 up off of seat 48.

it has been necessary in valves of this type to provide small orifices in the piston 36 to allow the inlet pressure to bleed through to the chamber 38 to equalize the pressure on bothsides of the piston, so that the greater pressurized area on the chamber side of the piston will keep the piston tightly seated. it is also customary to discharge the pressure from the chamber 38 into the main discharge line,

However, when a valve of this type, with the usual features as described in the preceding paragraph, is used with a highly pressurized and rapidly vaporizing extinguishant such as the Halon 1301 mentioned previously, it has been found that severe valve chattering occurs, which reduces the rate of flow of extinguishant through the valve to about one tenth of the desired rate. This is apparently due to the fact that when the valve opens and liquid extinguishant flows into the piping to the discharge nozzles, the flow resistance causes the pressure to build up at the discharge outlet of the valve, causing liquid extinguishant to back up through the pilot valve discharge line and enter the chamber 38. At the same time the extinguishant under pressure passes as a liquid through the small pressure equalizing orifices in the piston, expands to vapor, which cannot get out because of the blockage of the pilot valve discharge line. The resulting increase. in pressure in the chamber 38 causes the valve piston to re-seat, shutting off the flow of extinguishant through the discharge line. The above process then repeats itself, casuing continuous valve chatter.

However, it has been found that with a valve having the structure illustrated, in which the pilot valve discharge line is vented to atmosphere and no pressure equalizing orifices are provided in the piston 36, the valve operates satisfactorily with high pressure liquid extinguishants of the type previously mentioned, with no valve chattering, and adequate discharge rate. Although it would be expected that the lack of bleed oriflees in the piston would prevent the equalizing of pressure on both sides thereof, which would prevent the valve from closing properly, it has been found that with this type of extinguishant, sufficient leakage occurs between the piston periphery and the cylinder wall to provide sufficient vapor pressure in the chamber to close the valve after the pilot valve is closed.

The omission of the equalizing orifices also increases the operating speed of the valve. Although for ordinary fires the difference of a fraction of a second in valve operating time is of little significance, when the valve is used in a system which is expected to operate as an explosion suppression device, maximum speed of valve opening on receipt of a signal from the detector is essential.

With no bleed orifices in the main piston, when the pilot valve opens to dump pressure from the chamber 38, the rate of pressure drop in the chamber, and hence the rate of valve opening is greater in the illustrated device than if extinguishant were flowing into the chamber through equalizing orifices as the pilot valve is attempting to drop the pressure therein.

To operate as a system capable of suppressing an explosive type of fire, such as that produced by a spark ignited mixture of air and gasoline vapor, the extinguishant must be delivered by the system to surround the ignited flame ball in 250 milliseconds or less, since after that time the flame ball reaches such proportions that it is impractical to surround by extinguishant, and the pressure in an enclosed compartment resulting from the temperature rise of the burning gases becomes high enough to rupture the compartment walls.

In tests made on a valve of the general type illustrated with, however, the usual bleed orifices in the piston, the operating time from receipt of the signal from the detector amplifier to the solenoid to the time at which the valve is full open (as measured by the time of rupture of a seal over the valve discharge opening by the discharged extinguishant) is between and 130 milliseconds. Assuming an amplifier operating time of 25 milliseconds from receipt by the detector of radiation from the flame ball, only 95 to milliseconds are available for the extinguishant to flow through the piping and discharge from the nozzles. This amount of time has been found to be inadequate.

However, when an identical valve as tested above is modified to the structure illustrated and described herein, that is, with no bleed holes in the piston and the pilot valve discharging the chamber to atmosphere, the operating time, measured in the same manner, was between 9 and 14 milliseconds. Hence the time available for the extinguishant to pass through the piping and out of the nozzles is increased to between 21 l and 216 milliseconds, which time has been found adequate to allow the extinguishant to surround and extinguish a flame ball before it reaches an uncontrollable size.

Since certain obvious changes may be made in the valve and extinguishing system described herein, it is intended that all matter contained herein be interpreted in an illustrative and not a limiting sense.

I claim:

1. A discharge valve for a fire extinguishing system of tyhe type utilizing a container of vaporizible liquid under pressure, said valve having a seat and a piston closing the seat, said piston being slidable in a cylinder toward and away from the seat, the portion of the front face of the piston around the seat being pressurized by the container, the chamber and the rear face of the piston being pressurized to maintain the valve closed, means releasing the pressure from the chamber to actuate the valve, the means pressurizing the chamber being so dimensioned that the rate of flow of liquid extinguishant into the chamber when said means releasing the pressure from the chamber is actuated is less than the rate of flow of vaporized extinguishant out of said means.

2. A discharge valve as set out in claim 1 in which the chamber is pressurized only by leakage of extinguishant between the periphery of the piston and the cylinder.

3. A discharge valve as set out in claim 2 in which said means releasing the pressure of the chamber discharges the pressure of the chamber to atmosphere.

4. A discharge valve for use in a fire extinguishing system of the type utilizing a container of vaporizable liquid under pressure, said valve comprising a valve seat, a cylinder forming a chamber associated with said valve seat, a piston in the cylinder with its forward face normally covering the valve seat and being movable away from the seat into the chamber to open the valve, v

line for lifting said plunger to open the discharge line and release the pressure from the chamber to open the valve.

5. A valve as set out in claim I in which said means in said discharge line comprises a cam rotatable from outside the discharge line and a cam follower movable into and out of engagement with the face of said plunger covering the discharge line.

6. A fire extinguishing system, comprising a container of vaporizable liquid extinguishant under pressure and a discharge valve connected thereto, said valve comprising a main piston to open and close the main discharge line, said main piston being normally pressurized on both sides and an auxiliary piston normally closing a valve seat to an auxiliary discharge line, the opening of said auxiliary piston releasing pressure from one side of the main piston to allow said piston to open the main discharge line, fire detector means, solenoid means responsive to the detection of a fire by said detector means to lift said auxiliary piston off its valve seat, and means in said auxiliary discharge line manually operable from outside the discharge line to contact the auxiliary piston through the valve seat to lift said piston off of said seat.

Claims

4. A discharge valve for use in a fire extinguishing system of the type utilizing a container of vaporizable liquid under pressure, said valve comprising a valve seat, a cylinder forming a chamber associated with said valve seat, a piston in the cylInder with its forward face normally covering the valve seat and being movable away from the seat into the chamber to open the valve, the forward face of the piston around the seat being normally pressurized by the container, means pressurizing the chamber to the same pressure as the forward face of the piston whereby the greater pressurized area of the rear face of the piston maintains the piston against the seat, a discharge line from the chamber and a plunger in the pressurized chamber normally covering the opening to the discharge line, means in said discharge line movable toward and away from the unpressurized portion of the plunger covering the discharge line for lifting said plunger to open the discharge line and release the pressure from the chamber to open the valve.

5. A valve as set out in claim 1 in which said means in said discharge line comprises a cam rotatable from outside the discharge line and a cam follower movable into and out of engagement with the face of said plunger covering the discharge line.