A VALVE FOR USE IN FIRE EXTINGUISHING SYSTEMS

The prior art

The invention relates to a valve, in particular for use in connection with fire extinguishing systems in an area having a cooking zone and/or deep fat fryer, as stated in the introductory portion of claim 1.

Today, cooking zones and deep fat fryer installations are protected against fire by various types of systems. There are extinguishing systems which extinguish fires in pots, pans or deep fat fryers by carbon dioxide which is distributed over the scene of fire and thereby displaces the oxygen from the fire, which is extinguished thereby. It is also known to use extinguishing liquid with potassium carbonate or potassium sulphate, which is distributed over the burning oil. When the liquid contacts the oil, saponification occurs on the surface of the oil, whereby the fire is choked.

When carbon dioxide is used, the extinguishing effect ceases as soon as the gas has gone, involving the risk that the fire reignites. Moreover, the gas is dangerous to inhale. Potassium carbonate and potassium sulphate are highly basic, and the cleaning after the fire extinguishing is therefore complicated. Also, there is a risk of reignition of the fire if the saponification layer is decomposed before the pot, the pan or the deep fat fryer has been cooled down.

These drawbacks are not present in a method, wherein the installation is fire-protected with a water mist which is distributed with a high pressure system, which delivers a spray of finely divided small water drops on the surface of the burning oil, whereby the fire is extinguished, partly by dis- placement of the oxygen, partly by cooling of the surface of the oil.

This method, however, requires that the water to the water nozzles is distributed with a high pressure, and this may cause various problems, as a pressure loss in the pipes to the nozzle locations means that the nozzles disposed closest to the supply point of the pressure water receive the high- est liquid pressure and therefore distribute more water than those arranged further away from the supply point, thereby necessitating a greater capacity of liquid supply than is otherwise required.

The problem may be remedied by using pipes of a larger diameter, whereby the flow losses in the pipes are reduced, which, however, results in greater installation costs and an impaired architectural value. It has also been attempted to remedy the problem by using nozzles of different water resistance, but this method opens up the possibility of confusing nozzles and is therefore not allowed by many authorities.

The publication WO 02/26393 A1 discloses a nozzle for fire extinguishing systems in buildings. This system has an automatically adjustable outlet opening, so that the flow amount in a pressure area may be kept constant irrespective of the liquid pressure. The nozzle contains a mechanical stop which determines the desired liquid flow. As long as the liquid flow is below the desired one, it is changed in step with the liquid pressure until the desired liquid flow is reached. Then, the liquid flow is relatively constant until the pressure reaches a size which causes a pilot valve to open and leak liquid, so that the outlet opening is increased, resulting in reduced liquid pressure. Thus, the liquid flow is just constant over a preselected pressure range determined by the mechanical stop and the setting of the pilot valve.

A valve in which the flow amount is constant irrespective of the liquid pressure, is known e.g. from US Patent No. 4 791 956. In this valve, a valve body, which cooperates with a passage in the valve housing having a curved cross-section, is spring-biased toward a position having a larger flow

cross-section. A piston communicating with the valve body is affected by the liquid pressure in the system and presses the valve body toward a position having a smaller flow cross-section. The spring pressure may be adjusted from the outside by a hand grip.

This known valve is intended to be inserted into a conduit, as it has flanges for this use. The valve and the narrowed passage are located at the downstream side of the supply pipe and form an angle with the direction of the flow. The piston and the spring must therefore be positioned with the same angle with the supply pipe and extend obliquely out of the valve housing. The spring system of the valve is complicated because of this structure, and it occupies much space.

The object of the invention

The object of the invention is to provide a valve for a fire extinguishing system, so that uniform nozzles and relatively small pipe dimensions may be used, and so that the nozzles nevertheless distribute the same water flow irrespective of their positions in the pipe system and irrespective of the inlet pressure to the nozzle system.

This object is achieved with a valve, which is small and compact, and which is configured such that nozzles or assemblies of nozzles may be connected directly with the valve housing, which is supplied with liquid from a high pressure system, and where the valve discharges a constant liquid flow which is independent of the liquid pressure in the system, by constructing the valve in the manner stated in the characterizing portion of claim 1. This provides a very compact structure, as the closely built-together unit with the spring arranged at the rear side requires very little space, and, accordingly, it lends itself for use in systems like those involved here.

Such valves, which are also known under the designation constant flow valves, contain a valve body which cooperates with an opening or a seat in the valve housing, so that it may restrict the liquid flow more or less. The valve body is spring-biased toward a position with the greatest possible flow and is also connected with a piston or a similar displacement unit, which is under the action of the liquid pressure and thereby affects the valve body toward a more closed position.

If the pressure in the liquid system increases, the valve body is affected against the action of the spring toward a more closed position, whereas it opens more if the pressure decreases or is low. Hereby, substantially the same liquid flow is achieved irrespective of the variation of the pressure, as a high pressure corresponds to a relatively small flow area, while a lower pressure corresponds to a larger flow area, so that the outflowing amount of liquid becomes the same.

The desired flow amount may be adjusted by changing the spring pressure, there being, for any situation, an equilibrium between the spring pressure and the force from the piston affected by the liquid pressure. In most con- stant flow valves, there is an externally accessible screw by means of which it is possible to adjust the spring tension and thereby select the value of the flow amount.

With such valves according to the invention in the fire extinguishing system, the same flow is achieved through all nozzles or nozzle assemblies, as the flow through the nozzles located closest to the pressure water source is reduced, while the flow through the nozzles further out in the system, where the pressure is lower because of the pressure loss in the pipes, increases, thereby neutralizing the differences which occurred previously. Therefore, small pipe dimensions may be used without the previously known drawbacks.

As stated in claim 2, the nozzle pipes or openings are present in the valve housing between the valve body and the displacement body of the unit, i.e. immediately after the valve body and the associated narrowed passage. These nozzles or nozzle pipes form angles with the valve housing. Thereby, the valve gets an additionally compact structure.

As stated in claim 3, the displacement body may be a diaphragm which extends between the valve body and a wall in the housing outside the flow path. As stated in claim 4, it may also be a piston which is integrated with the valve body and cooperates with a cylindrical part of the valve housing.

Expediently, as stated in claim 5, the spring is a compression spring which engages the rear side of the piston or of the diaphragm.

The spring force of the compression spring may be adjusted from the outside by means of a screw, as stated in claim 6.

As stated in claim 7, the nozzles may be arranged in nozzle pipes which extend substantially perpendicularly out from the valve housing directly at the outlet side of the valve body. As stated in claim 8, the nozzles may be provided in the valve housing itself and form an angle with the axis of the housing.

As stated in claim 9, the valve body with the built-together displacement unit may be configured with a face which engages the valve housing when the valve is in a fully open position. This ensures that the liquid flow is blocked when the system is in a position of rest, and access to the extin- guishant is allowed only when pressure is applied to the inlet side.

In a further embodiment of the invention, at least one nozzle is integrated in the piston, said position being provided with a pipe on the spring side which

is connected with the pressure side of the valve through oblique bores in the piston, and at whose end the nozzle is provided, said pipe extending out through the bottom of the valve housing, as stated in claim 10.

In this manner, when the valve housing is disposed vertically, as is preferred, a central nozzle is achieved which is directed downwards from the valve housing. At the same time, the pipe may form a support for the spring which is positioned around the pipe.

The pipe need only protrude out through the bottom of the valve housing when the system is in operation. Therefore, as stated in claim 11 , the hole in the bottom of the valve housing may be closed by a plug, which is ejected from the pipe when the valve is moved downwards. The nozzles are protected hereby, and the valve housings are closed outwardly when the system is at rest.

In an embodiment, the valve according to the invention may be provided with a lock, which holds the valve body in the inactive position of rest, and which is adapted to be released when a heat sensitive part is destroyed, as stated in claim 2. Hereby, the valve is retained in the position of rest, until the temperature is so high that the heat sensitive part, which may be a glass ampoule, melts.

The drawing

The invention will be explained more fully below with reference to the drawing, in which

fig. 1 shows a section through the valve according to the inven- tion in a pipe system for a fire extinguishing system,

figs. 2 and 3 show sections through embodiments of the valve,

figs. 4 and 5 show an embodiment with a nozzle at the bottom of the valve housing, and

fig. 6 shows an arrangement with a lock which holds the valve body in an inactive position.

Description of the exemplary embodiments

In fig. 1 , water flows from the supply pipe 2 through an inlet 3 having a filter 4 and an upper chamber 5 into a cavity 6 in the valve housing 1. A valve body 7, together with the valve housing, defines a gap 11 which allows maximum flow of water in the shown position. If the water is under sufficient pressure to overcome the force from the spring 8, the seal between a sealing body at the lower side of the valve body and the housing is removed at the location indicated by the reference numeral 9, whereby the water flows out into the underlying cavity 10 and further on to nozzle pipes 14 and further out through the nozzles 15. A further increase in pressure moves the valve body downwards, which thereby narrows the gap 11 , 12, as the water pressure affects a diaphragm 13 which is attached to the valve body and to the inner side 16 of the housing 1 , and on whose lower side the spring 8 acts, thereby compressing the spring. The cavity 17 below the diaphragm 13 communicates with the atmosphere at the location indicated by the ref- erence numeral 19. Depending on the pressure in the system, a state of equilibrium occurs, determined by the pressure and the spring force. If the pressure increases, the diaphragm is compressed by virtue of its large area, and the valve body closes the gap 11 more and thereby the area available to the water flowing therethrough. If the pressure decreases, the valve correspondingly opens the flow area. This means that the outflowing amount of water, which depends on the pressure and the area which is

available, remains substantially constant irrespective of any pressure variations and irrespective of the positions of the valve and the associated nozzles in the pressure system. The spring tension may be changed by a finger screw 21 , 22 which presses on the lowest abutment 22 of the spring, whereby the position of equilibrium and the flowing amount of water may be adjusted.

Fig. 2 shows an embodiment where the nozzles 15a are provided in the valve housing itself, and where the water is supplied through bores 23 in the housing.

Fig. 3 shows an embodiment where the displacement element is a piston which is integral with the valve body 7b, and which has sealing rings 24, and which cooperates slidingly with the cylindrical lowermost part 16 of the housing.

Fig. 4 shows an embodiment where a nozzle 15d is also provided at the bottom of the valve housing. At the bottom, the piston is provided with a pipe 28 to which the water flows through oblique bores 25 in the piston 7d. The pipe 28 extends out through the bottom of the valve housing through guides 26, 27 and carries the nozzle 15d at its lowermost end.

As shown in fig. 5, it is not necessary that the pipe 28 protrudes through the bottom when the system is in a position of rest. Therefore, in this embodi- ment, a plug 29 is arranged at the bottom of the valve housing, said plug being adapted to be pushed out of the pipe when the valve body 7 moves downwards from the position of rest.

Fig. 6 shows an arrangement where the valve body is locked in its inactive position by two locking elements 30, which lock the valve body when they are blocked from each other. The two locking elements are held in a fixed

state by a body 31 , such as a glass ampoule, which is adapted to be destroyed by heat. When the ampoule has been destroyed, the two locking elements are released and may drop out through the bottom, following which the valve body may be moved downwards.

The details of the valve may be constructed in various ways. The lock may be formed by the glass ampoule itself, which may be arranged vertically between the bottom of the housing and the valve body. The lock may also be released by an electrical actuator, either in the form of a hot wire or by a bolt which is ejected into the glass ampoule.