A sprinkler head triggering apparatus

FIELD OF THE INVENTION

The present invention refers to a sprinkler head triggering apparatus, comprising a spray nozzle with an actuator being releasable by heating to a certain temperature, and which normally holds a valve piston in a closed position against a valve seat, which valve piston, at release of the actuator, is movable in a piston sleeve in the direction away from said seat, for opening a flow passage from a feed line for pressurized water to the spray nozzle.

BACKGROUND OF THE INVENTION

Sprinkler heads are used in sprinkler systems for fire extinguishing inside plants, buildings and on ships. Often, such a sprinkler head is provided with a triggering device comprising an actuator, e.g. a glass bulb which is actuated by heating to a high ambient temperature. It is also known to provide such a glass bulb with an electrode which may explode the bulb electrically by remote control, e.g. by a signal from a smoke detector or for functional testing.

A drawback with sprinkler systems which are equipped with such actuator means is that the functional testing of the system is very difficult to perform. For example, each bulb must be exchanged and the restoration of the system to normal function thus takes a long time. Normally there are regulations for performing such function testing according to a certain regularity.

Therefore, demands for the opportunity of a simple and effective functional testing has led to the development of sprinkler systems with one or more centrally located actuator apparatuses with electrically controlled flow

valves for actuation of an optional number of spray heads, either for functional testing or for detection of an alarm, e.g. via a smoke detector. Thus, the spray heads at these sprinkler systems are not provided with the actuator, and the feed lines between valve units and spray heads are consequently dry.

A substantial drawback with these "modern" sprinkler systems, is that each individual spray head, or individual group of sprinkler heads, which shall be individually manoeuvrable, must be provided with a separate feed line to the valve unit. This involves installation of a lot of feeder pipes in parallel, which makes the installation more expensive. Also, such a system leads to a higher flow resistance than a system which branches away from a common main line.

THE TECHNICAL PROBLEM

One purpose of the present invention is therefore to provide a triggering apparatus which can be released directly both mechanically by means of a heat fuse, and also by means of electrical remote control, e.g. via a smoke detector, without the need for particular flow valves. Another object is to provide a triggering apparatus which is simple to test functionally.

THE SOLUTION

This is accomplished according to the invention, because the flow passage is openable in the normal closed position of the valve piston with intact actuator, via a remote control operated pilot piston.

Advantageous variants of the invention are described in the depending claims.

DESCRIPTION OF THE DRAWINGS

The invention will be described hereinafter with reference to embodiments shown in the enclosed drawings, wherein Fig. 1 is a partly sectioned view of a triggering apparatus designed in accordance with the invention, Fig. 2 shows in a slightly larger scale a secondary piston belonging to the triggering apparatus, Fig. 3 shows a valve piston belonging to the triggering apparatus, and Fig. 4 shows a bulb screw belonging to the triggering apparatus.

DESCRIPTION OF EMBODIMENTS

The triggering apparatus according to the invention is in the following embodiment shown together with a sprinkler head of a special high pressure type, but the invention is not limited to this type of sprinkler nozzles.

The nozzle comprises a holder 10 which forms an attachment for a nozzle head 11. This head 11 is in its turn mounted in the holder 10 by means of a bulb screw 12 which projects with one of its ends into the holder and which carries a bulb protector 13 at its other end. A glass bulb 14 is mounted at the outer end of a valve piston 15 which is movable journalled inside the bulb screw 12, in such a way that the piston 15 is held in a closed position against a valve seat. This valve seat is formed by a conical part 16 of a secondary piston 17.

If the glass bulb 14 is subjected to heat above a certain temperature, e.g. 70°C, the bulb breaks and the valve piston 15 is able to move in the direction downward in Fig. 1, by the action of a fluid pressure prevailing within the space 18. This pressure is transmitted to the space via a feed line which is not shown in the drawing and which is

connected at right angle to said space, acting against the end edge of said valve piston 15, which in this end portion is provided with an axially projecting, central bore 19. Thus, when the valve piston 15 is pressed away from the seat of the secondary piston 17, water penetrates into the central bore 19 and flows further via a first angular passage 20 through the piston wall and a second angular passage 21 through the bulb screw 12 into a space 22 between the holder 10 and the sprinkler nozzle head 11.

Now the water is able to flow out of the sprinkler head via not shown channels in the contact surfaces between the holder 10 and the nozzle head 11. These contact surfaces, except said channels, are sealed by means of an 0-ring 23.

Thus, the above described working process takes place when the glass bulb is heated above a certain temperature. At the above described high pressure sprinkler system, it is convenient if the pressure fall in the feed line, at release of the sprinkler head, influences a pressure detecting valve which starts pumping for supply of sprinkler water with a high pressure, e.g. 200 bar.

Functional testing or release of the sprinkler head in any other way, e.g. via a smoke detector or from a command central, is made possible in accordance with the following.

The secondary piston 17 is movable journalled in a piston sleeve 24 inside the holder 10, which piston sleeve is coaxial with the guide for the valve piston 15 in the bulb screw 12. A helical spring 25 rest on a angle shoulder 26 inside a pilot piston cylinder 27 which is screwed on to the upper end of the holder 10. The spring 25 presses with a small force against an end edge 28 on upper side of the secondary piston, as it is shown in Fig. 1, or the left side as it is shown in Fig. 2.

As is best shown in Fig. 2, the secondary piston 17 is provided with a first channel 29, which between the two ends of the two ends of the piston 17 and which forms a connection between the space 18 at one side of the piston, and the space 30 which houses the helical spring 25, so that equal pressure prevails on both ends of the piston. Also, the secondary piston 17 is provided with a second channel 31 arranged in parallel, which has a larger cross section than the first channel 29. This second channel 31 runs along the centre axis of the piston and is normally closed by a pilot piston 32 which is movable arranged inside the pilot piston cylinder 27, coaxial with the valve piston 15 and the secondary piston 17.

The pilot piston 32 is normally held in its closed position against the outlet of the second channel 31 of the secondary piston 17 by the action of a helical spring 33. Also, the pilot piston is manoeuvrable by means of a solenoid 34 which is electrically controlled via a cable connection 35.

During activation of the solenoid 34, the pilot piston 32 is pulled upwards in Fig. 1 against the action of the helical spring 33. This opens the channel 31, which leads fluid from the space 30 via the central bore 19 of the valve piston, the angular passages 20, 21 and the sprinkler channels and the space 22 out of the sprinkler head. At the same time a smaller flow of fluid takes place from the space 18 via the second channel 28. This limited flow does not manage to compensate for the pressure difference between the two ends of the secondary piston, i.e. between the two spaces 18, 30, which results in that the piston 17 is pressed/pulled in the direction upward in Fig. 1. This opens the valve seat between the secondary piston 17 and the end of the valve piston 15 and feeding of sprinkler water takes place in the same manner as in the preceding example of function.

This flow may be interrupted by a deactivation of the solenoid. This shuts off the channel 31 and the secondary piston 17 is pressed down in Fig. 1 against the end of the valve piston 15 and closes the bore 19.

Thus, the functional testing can be made by means of a short activation of the solenoid.

The invention is not limited to the above described embodiment, instead more variants are conceivable within the scoop of the following claims. For example, the valve piston, the secondary piston and the pilot piston do not have to be coaxially arranged along a common longitudinal axis. The electrically controlled release of the sprinkler head do not have to take place via a secondary piston, but the pilot piston may act directly against the valve piston.