Patent Publication Number: US-3878898-A

Title: Heat detection system

Description:
United States Patent 1 1 Marshall 1 HEAT DETECTION SYSTEM [75] lnventor: Ian Marshall, Shaw. England [73] Assignee: Mather 8L Platt Limited, Lancashire.  
 England [22] Filed: Nov. 6, 1972 [21] App]. No.: 303,909  
 [30] Foreign Application Priority Data Nov. 6. 1971 United Kingdom 51665171 [52] U.S. Cl 169/60; 169/16 [51] Int. Cl. A62c 37/02 [58] Field of Search t. 169/2 R. 5. 11, 16, 26, 169/60 [56] References Cited UNITED STATES PATENTS 2.708.976 5/1955 Boice t. 169/26 1 Apr. 22, 1975 2.829.720 4/1958 Heigis ct al. 169/1 l 3.568.774 3/1971 Meoule 169/26 X 3,776,313 12/1973 DePalma 169/26 X 3.791.450 2/1974 Poitras 169/37 Priman E.\&#39;aminerL1oyd L. King Assistant Examiner-Michael Mar Attumqv/Agem, or FirmSughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT A heat detection system which has particular app1ication in a fire fighting system and which consists of two pneumatic chambers connected to a pressure sensitive activator serving to operate the fire fighting system. One of the chambers is a detector member while the other is thermally insu1ated to act as a compensator for low rates of temperature increase.  
 17 Claims, 9 Drawing Figures PATENTEDAPR22|975 SHLU 1 BF 4 FIG.7  
 HEAT DETECTION SYSTEM This invention relates to a heat detection system employing the principle of using rise in fluid pressure in a closed pipe on increase in temperature to actuate a fire-fighting system and/or fire alarm.  
  According to the present invention there is provided a heat detection system especially for use in actuating a fire-fighting system and/or fire alarm, the system comprising a pressure sensitive actuator for operating the fire-fighting system and/or fire alarm, a chamber containing fluid under pressure in communication with the actuator and serving as a detector, a thermallyinsulated chamber also containing fluid under pressure and in communication with the actuator and serving as a compensator on low rates of temperature rise, the chambers being locatable at an area where it is desired to detect temperature rise.  
 Preferably, each chamber is a pipe.  
 Preferably also, each chamber is a closed loop pipe.  
  Preferably, a sensitivity control is provided between the chambers.  
  Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:-  
  FlG. l is a diagrammatic view showing the heat detection system;  
  HO. 2 is a view showing the heat detection system associated with a fire-fighting deluge system;  
  FIGS. 3 and 4 are diagrammatic view of the actuator and the means for operating the fire-fighting system;  
  H05. 5 and 6 are sectional views of the sensitivity control; and,  
 FIGS. 7 to 9 are detail views of modifications.  
  The heat detection system comprises essentially a low fluid pressure balanced detector arrangement adapted on registering a predetermined pressure value to effect operation of a fire-fighting system and/or fire alarm.  
  Referring to HO. 1, the system shown there comprises two loops l0 and 11 of fine gauge copper tubing, the loops l0 and ll being connected to opposed ends of a differential pressure sensitive actuator 12, the whole being fed from a fluid pressure supply of any convenient form. The fluid is preferably air but any other convenient gas or compressible liquid may be employed. An example of the pressure employed in the system is between 20 and 30 ounces per square inch.  
  The closed-loop pipes 10 and ll are located at the desired detection zone as will be described later.  
  The pipe 10 is of plain copper tubing and acts as the detector proper while the pipe 11 is thermally insulated and acts as a compensator on low rates of temperature rise. The pipe 11 has insulating material wound round about it; such material being, for example an inner layer of bitumised slag wool and an outer layer of woven asbestos. Other insulating materials may, of course, be employed or the pipe 11 may be formed of an inherently thermally insulated material, for example a plastics material.  
 The pipes 10 and 11 may be other than copper.  
  Between the detector and compensator pipes 10 and H is a sensitivity adjustment 13 which may be in the form of a porous plug or cock whose opening can be varied as described later.  
  It will be manifest that the compensator pipe 11 will prevent unnecessary operation of the detection system, i.e., on small rate of temperature increase. However, in  
 the event of fire, the rate of temperature rise will far exceed the compensation factor thereby causing a pressure difference sufficient to trigger the actuator 12 and so operate the fire-fighting system and/or alarm.  
  Referring now to FIG. 2, the heat detection system of FIG. 1 is shown associated with a fire-fighting deluge system suitable for disposition, say, in a hanger bay The pipes 10 and II extend along the roof of the bay and are connected to the actuator 12 (the sensitivity control 13 is omitted for simplicity reasons).  
  The deluge firefighting system comprises an arrangement of water distributing pipes 14 (normally empty of water) having outlet nozzles or sprays 15. The water distributing pipes 14 are connected via a water valve 16 which is normally closed, to a pressurised water supply. The valve 16, normally called a deluge valve&#34; is well known and of conventional construction and is normally held closed by a latch operated by a diaphragm which is subject to air pressure such that a fall in pressure allows the diaphragm to move to release the latch so permitting the water pressure to open the valve 16 flow along the pipes 14 and out of the nozzles 15.  
  Reference is now made to FIGS. 3 and 4 where the pipes 10 and 11 are shown diagrammatically. The actuator 12 comprises a housing containing two diaphragms l7 and 18 interconnected by a rod or bar 19, the detector pipe 10 opening on to the diaphragm l7 and the compensator pipe ll opening on the diaphragm 18 to give a balanced arrangement, the diaphragm l7, however, being spring-loaded, indicated at 20 so that the actuator 12 is biassed against the detector pressure.  
  The rod 19 has pivoted to it a lever 2| having at its other end a hook-like formation 22. A lever 23 of inverted U cross-section and L-shape in elevation is pivoted at 24 inside the housing and is connected to the lever 21 by a pin 25. This lever 23 is acted on by a spring 26 which tends to urge the lever 23 and consequently the lever 21 downwardly. A third lever 27 pivoted intermediate its ends at 28 has one end acting on the lever 23 against the spring 26 while its other end is acted on by an adjustment screw 29. It will be manifest that adjustment of the screw 29 will permit variation of the spring effect on levers 21 and 23.  
  The hook-like formation 22 engages a nose 30 of a substantially vertical lever 31 pivoted at its bottom at 32 and carrying nearer its top a weight 33.  
  The degree of engagement between formation 22 and nose 30 is determined by the spring 26 and screw 29.  
  A disengagement between the formation 22 and the nose 30 allows the weight 33 to pivot the lever 31 downwardly and this causes a projection 31A to strike a further lever 34 so as to pivot same downwardly about its pivot axis 35. The lever 34 has pivoted thereto a small arm 36 carrying a roller 37 engaging an operating weight 38 at the bottom of a track 39 on the ope rating weight 38. The arrangement is such that downward pivoting of the lever 34 causes the roller 37 to move slightly laterally from its position where it supports the operating weight 38 into the track 39 thus permitting the operating weight 38 to fall down a support bar 40 and strike a bellcrank lever 41 pivoted at 42. This bellcrank lever 4l, at one end. is secured to a sleeve valve 43 which, when opened, causes a fall in air pressure in the airline 44 of the diaphragm-operated valve 16 thus effecting operation of the deluge system.  
  The other end of the bellcrank lever 41 has a formation 45 for acting on a micro-switch 46 which is part of an electric circuit giving a visual and/or audible indication of operation of the deluge system. for example a fire alarm.  
  An adjustment screw 47 is provided for the lever 34 to ensure. when the lever 34 is re-set in its substantially horizontal position, that the roller 37 always takes up the same position at the bottom of the track 39.  
  Before describing the operation of the system more fully reference is made to FlGSv 5 and 6 which show one form of sensitivity control. This comprises a porous carbon plug 48 of cylindrical construction and closed at one end. say the compensator line end. This plug 48 is supported in a casing 49 and is held by an elastomeric ring 50. A hollow adjusting screw 51 screwengages in the casing 49 and grips the porous plug 49 so that the plug can be exposed to a greater or or lesser degree relative to the compensator line 11. This permits a greater or lesser degree of leakage thus varying the sensitivity of the actuator since the greater the leakage the less sensitive is the actuator so that it will operate at a higher rate of temperature change.  
  In operation, ambient temperature increases are ca tered for by the compensator pipe as are low rates of temperature increase. lf, however, there is a high rate of temperature increase. expansion of the air in the detector line causes imbalance in the actuator 12 so moving the diaphragm 17 against its spring 20 and this moves the rod [9 axially to pivot levers 21 and 23 so disengaging the formation 22 and nose 30. This, as aforesaid. effects pivoting of levers 31 and 34, falling of the operating weight 38 and opening of the sleeve valve 43 thus releasing air pressure on the diaphragm of the deluge valve [6. The latter is therefore unlatched. opens and water under pressure is delivered downwardly onto the firev At the same time an audible and/or visual indication of operation is given via the micro-switch 46.  
  If the rate of temperature increase was extremely slow then it is conceivable that the detection system would not operate since the actuator would always be in a balanced condition. While such a situation is considered almost impossible to achieve, a safety factor is given to the deluge system. This system factor is in the form ofa pressurised air pipe system 52 disposed across the roof of the bay and having outlets closed by heat sensitive bulbs 53 which operate at a predetermined temperature irrespective of the rate of increase in temperature. When one or more of these bulbs 53 burst the air pressure in the system 52 and airline 44 falls so operating valve 16 as aforesaid.  
  The heat detection system is extremely efficient in use, economic to manufacture and is non-electrical so that it can be used in areas where there is no electricity supply or where such a supply is undesirable for safety reasons.  
  FIG. 7 shows an arrangement in which the detector and compensator pipes 54 and 55 are straight and not formed in closed loops.  
  FIG. 8 shows an arrangement of spot detectors in which pairs of small cylinders are scattered above a surface to be protected, one cylinder 56 of each pair being a detector cylinder while the other cylinder 57 is an insulated compensator cylinder. In this instance, all the cylinders are connected to the actuator by insulated pipes 58.  
  Reference is now made to FIG. 9 which is a modification of the system described with reference to FIGS. 1  
 to 6. Here, we have several zonal detectors operating a common deluge valve release mechanism. lt is not proposed to describe this embodiment in detail since its operation will be manifest to a person skilled in the art. Suffice it to say that there is a common air supply 60 to the various actuators 61 via a pressure regulator 62 and an air dryer 63. Each actuator 61 has associated with its sensitivity control 64 a pressure gauge 65 and low pressure alarm switch 66 which serve to indicate which zone has operated.  
  The diaphragm operated rods 67 of the actuators 6! are interconnected by a common bar 68 to which is pivoted a common hooked lever 69 for engaging a single weighted lever 70, the equivalent of 31 of H65. l to 6.  
  In this arrangement there will be between the deluge water valve and the water distribution piping of each zone another valve conveniently operated from the actuator so that water is fed only to the required zone.  
 What is claimed is:  
  l. A heat detection system for actuating a fire fighting system, a fire alarm, or the like, the system comprising: a pressure sensitive actuator, a chamber containing fluid under pressure in communication with the actuator and serving as a detector, a thermallyinsulated chamber also containing fluid under pressure and in communication with the actuator and serving as a compensator on low rates of temperature rise, the chambers being locatable at an area where it is desired to detect temperature rise.  
  2. A heat detection system as claimed in claim 1, in which the chambers are defined by pipes for extension across a detection zone.  
  3. A heat detection system as claimed in claim 2, in which each pipe is in the form of a closed loop.  
  4. A heat detection system as claimed in claim 3 in which the pipes are formed of metal. the compensator pipe being wrapped in a heat insulating material.  
  5. A heat detection system as claimed in claim 2 comprising a sensitivity control.  
  6. A heat detection system as claimed in claim 5 in which the actuator is a balanced fluid pressure dia&#39; phragm unit.  
  7. A heat detection system as claimed in claim 6. in which the diaphragm unit is connected to a mechanical operating mechanism adapted to initiate operation of a fire-fighting system, a fire alarm. or the like.  
  8. A heat detection system as claimed in claim 7 in which the diaphragm unit comprises a pair of spaced diaphragms interconnected by a rod. one of the diaphragms being operated on by detector fluid pressure while the other is operated on by compensator fluid pressure. and the diaphragm assembly being biassed against detector fluid pressure.  
  9. A heat detection system as claimed in claim 6, in which the sensitivity control is a porous plug between the detector and compensator pipes and is adjustable to vary the leakage therebetween thus varying the diaphragm unit sensitivity.  
  10. A heat detection system as claimed in claim 7 in which the mechanical operating mechanism is pivoted to the diaphragm connecting rod and comprises a piv otal lever releasably engaging a weighted lever pivotal to move an operating weight supporting lever so that the operating weight can fall and initiate operation of a firefighting system, a fire alarm, or the like.  
  ll. A heat detection system as claimed in claim l0 comprising means for varying the degree of engagement between the pivotal and weighted levers.  
  12. A heat detection system as claimed in claim 6 comprising a plurality of detector and compensator pipes and diaphragm units connected so as to operate a common mechanical operating mechanism.  
  13. The combination of a heat detection system comprising a pressure sensitive actuator, a chamber containing fluid under pressure in communication with the actuator and serving as a detector, a thermallyinsulated chamber also containing fluid under pressure and in communication with the actuator and serving as a compensator on low rates of temperature rise, the chambers being locatable at an area where it is desired to detect termperature rise. and a fire-fighting system actuated by said heat detection system.  
  14. The combination as claimed in claim IS in which the operating weight is adapted to contact a lever and open an air valve thus permitting operation of a diaphragm to open the main water valve of the firefighting system.  
  IS. The combination as claimed in claim 13 in which the fire-fighting system is a deluge system.  
  16. The combination as claimed in claim 15, in which the fire-fighting system incorporates a pressurised pipe system mounting heat responsive bulbs adapted to burst at a predetermined temperature thus releasing air pressure and permitting operation of the main water valve.  
 17. The combination of claim 13 further comprising a fire alarm actuated by said heat detection system.  
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