US2880808A

US2880808A - Buoyancy water flow detector and sprinkler system embodying the same

Info

Publication number: US2880808A
Application number: US648952A
Authority: US
Inventors: Arthur B Hube
Original assignee: American District Telegraph Co
Current assignee: American District Telegraph Co
Priority date: 1957-03-27
Filing date: 1957-03-27
Publication date: 1959-04-07
Anticipated expiration: 1976-04-07

Description

TO SUPERVISORY STATION April 7, 1959 A. B. HUBE BUOYANCY WATER FLOW DETECTOR AND SPRINKLER SYSTEM EMBODYING THE SAME Filed March 2'7, 1957 2 Sheets-Sheet 1 FlGil.

TRANSMITTEFI April 7, 1959 B. HUBE 1 BUOYANCY WATER FLOW DETECTOR AND SPRINKLER SYSTEM EMBODYING THE} SAME 2 Sheets-Sheet 2 Filed March 27, 1957' m mm United States Patent BUOYANCY WATER FLOW DETECTOR AND SPRINKLER SYSTEM IEMBODYING THE *SAME Arthur B. Hube, Huntington Station, N.Y., assignon to American District Telegraph Company, Jersey City, NaL, a corporation of New Jersey alarms for water flow operated sprinkler alarm systems such as may be utilized for operating an electric alarm system for causing an alarm when sprinkler heads discharge.

In suchelectric alarm systems retards are provided to desensitize the system to an extent necessary to avoid 'tlie'trans'mission of false alarms due to water supply pressure variations and surges. While in general, shorter retard intervals are preferred, it is desirable under cer- 'tain circumstances to provide longer retard intervals. For example, such is the case where the sprinkler system may-be supplied from water mains'in which there may be a sharp rise in pressure as may result from the difference in demand for water during night time as compared to that required during day time or between week day and weekend or holiday service conditions. In such instances there may be a surge of water into the sprinkler system which may continue for a substantial length of time, thirty to forty-five seconds or more.

Normally, the retard mechanisms provided are of the type which do not-require an appreciable lengthv of time to recycle and may be said to be instantaneously recycling. In the event such a retard mechanism, whether of one type or another, is provided with a retard interval of approximately one minute it will be appreciated that whena sprinkler head opens due to a fire and the alarm valve is actuated to initiate the operation of the alarm signaling mechanism the retard mechanism operates to prevent the operation of the signaling mechanism until its retard interval has elapsed. Now, if, before the retard intervalhas elapsed, adisturbance in the water fiow should occur which even only. momentarily restores the alarm valve to its normal condition, the retard mechanism, being ofthe instantly recycling type, resets itself with the result that the alarm, condition must now extend through a second retardinterval.

This situation isespecially undesirable'inthe case of large sprinkler installations subjected to sharp fluctuations in water main supply pressures which would necessitate the longer retard intervals. Here, a fire which only causes a relatively small number of sprinklers to open may fail: entirely to initiate an alarm signal due to the relatively small drain through the few open sprinklers from the relatively large capacity system which'would cause only intermittentopening and closing of the alarm valve at a rate insufiicient to permit the retard mechanism to run through its retard interval.

'- It is, therefore, a-principalobject of this invention to provide a water flow detectorand alarm system especially 2,880,808 Patented Apr. 7, 1959 well suited for use at locations subjected to sharp varia, tions in water supply pressure.

Another object is to provide a water flow detector and alarm system in which relatively long retard intervals may be provided without incurring the risk of a failure to-signal an alarm in the event of afire.

A more specific object is to provide a water flow detector of relatively simple construction which in op eration is substantially independent of the pressure in the system in which it is used and which together with a fast-to-make, slow-to-break switch, provide a desired interval after cessation of the flow of waterinitially sensed during which the switch contacts remain conductively connected. l J In accordance with the present invention a sprinkler signal alarm circuit connected so as to respond to actuation of an alarm valve between the water mains and the sprinkler system may be provided with a conventional retard mechanism which delays for a predetermined retard interval, the transmission of an alarm signal following actuation of the alarm valve. Between the signal circuit and the alarm valve and responsive to the latter there is provided a buoyancy type water flow detector and a switch actuated thereby. The water flow detector is preferably constructed so as to respond substantially in the same manner to water under widely varyingpressures. The switch is constructed so that once actuated a predetermined delay period is providedafter restoration of the water flow detector before the switch contacts are restored to their unactuated condition.

Further objects as well as advantages of the present invention will be apparent from the following description and the accompanying drawings in which Figure l is a diagrammatic view of a. sprinkler alarm system constructed in accordance with the present invention;

Figure 2 is a cross-sectional view on an enlarged scale of one of the water flow detectors and switches shown in Figure 1; and

Figure 3 is a similar view showing the parts in the position assumed in response to flow of water through the associated alarm valve.

Referring now to the drawings in detail, network 10 is of the type which may be installed in a subscriber's premises in conjunction with a fire sprinkler system 11. The network includes two

loop circuits

12 and 13 connected in series through an impedance element shown as resistor 14. Current normally flows through the

loop circuits

12 and 13 but due to the presence of series resistor 14 insuflicient current to operate alarm relay'15 is available. When, as will be more fully pointed out hereinbelow, resistor 14 is short circuited suflicient current to actuate relay 15 is provided thereto and it in turn actuates retard mechanism 16, which upon expiration of its retard interval actuates the transmitter, the latter thereby transmiting an alarm signal to the supervisory station. As shown,

loop circuits

12 and 13 are connected by

conductors

12a and 13a respectively to the opposite sides of one or more normally open contacts to be described in detail hereinbelow and any one of which when closed serves to short circuit resistor 14.

As shown in Figure 1 there is connected to a water supply main 17 one or more sprinkler risers 18 each of which is connected, through an alarm valve 19 to a pluralityof sprinkler heads (not shown). "Alarm valves counterclockwise rotation of switch 41. leave chamber 47 and uncover contacts 51 must now flow 19 may be of conventional structure having a clapper 20 which when moved off its seat in response to a flow of water causes the opening of an alarm port 21 which communicates through conduit 22 with the inlet 23 of water fiow detector 24.

Water flow detector 24 comprises a housing 25 having a generally cylindrical plug chamber 26 formed in the floor or base 27 thereof and which communicates with a float chamber 29 formed within the housing through an L-shaped filling bore or port 28 opening in the floor of both chambers. An operating rod 30 extends vertically in housing 25 and projects through aperture 31 formed in. the top 32 thereof. Intermediate its ends, operating rod ,30 is connected to a float 33 which normally rests on a stop 27a projecting upwardly from base 27. Adjacent to its lower extremity operating rod 30 is connected to a valve body 34 provided with a transverse open ended passageway 35 communicating with a longitudinal passageway 36 and together forming a bore affording communication between inlet 23 and filling port 28. A cylindrical plug 37 is incorporated in valve body 34 below passageway 35 and is adapted more or less to close inlet 23 depending upon its vertical position as determined by the extent to which float 33 is displaced due to the liquid level within chamber 29. Float chamber 29 communicates with the atmosphere through a restricted drain opening 38 provided in base 27. To insure that float 33 is not directly aflected by water flowing from filling port 28 but only responds to the level of water in chamber 29, a deflector 28a of somewhat larger diameter than the opening of port 28 is positioned adjacent thereto and is connected to base 27.

Water entering inlet 23 passes through the bore formed by

passageways

35, 36 and through filling port 28 into float chamber 29. As the float chamber is being filled and float 33 rises with the water level, plug 37 on valve body 34 rises to obstruct inlet 23. At the same time water passes out through restricted drain 38 but at a rate substantially less than at which water may enter through inlet 23 so that as water continues to enter through the inlet, float 33 and plug member 37 assume an equilibrium position when the amount of water leaving through the drain is balanced by that entering through the inlet. Preferably float 33 and chamber 29 are proportioned as shown so that the volume occupied by float 33 is less than that of chamber 29 by an insubstantial amount to the end that operation of float 33 to shift trod 30 to its actuated or raised position is substantially independent of the pressure under which water enters inlet 23.

The upper end portion of operating rod 30 is provided with a pair of

parallel arms

39, 40 which govern a mercury switch 41 now to be described. Mercury switch 41 comprises a sealed envelope 42 mounted for rotation about pivot 43 and having an operating lever 44 extending between and disposed for engagement by

arms

39, 40. Battle 45 divides the interior of envelope 42 into two

compartments

46, 47 which communicate through baffle 45 by means of a restricted aperture 48 and a spill tube 49. A pool of mercury 50 is provided in envelope 42 which serves to bridge electrical contacts 51 provided in chamber 47.

With the parts in their respective positions as shown in Figure 2, mercury 50 is in chamber 46. Upon actuation of operating rod 30 due to the entrance of water into chamber 29 the rod rises rotating lever 44 and thereby envelope 42 clockwise. The mercury readily flows through the relatively large opening provided by spill tube 49 into chamber 47 there bridging contacts 51.

'Return of float 33 and rod 30 to their normal positions upon cessation of water flow through inlet 23 causes Mercury 50 to through restricted aperture '48 which is so proportioned with-respect to the volume .of mercury which must flow 4 therethrough before contacts 51 are opened as to ensure a rate of flow commensurate with the time delay desired.

Operation of the system as a whole will now be described. It may be noted by reference to Figure 1, that contacts 51 constitute the normally open contacts to opposite sides of which

loop circuits

12 and 13 are connected as hereinbefore described. With the system in a quiescent state, current as limited by impedance element 14 passes along the series connected

loop circuits

12 and 13 as well as series connected alarm relay 15 in an amount insufficient to cause relay 15 to pick up. Let it be assumed that retard device 16 provides a retard interval of 60 seconds while switch 41 is proportioned to provide a time delay before opening its contacts of about 20 seconds, it being preferred that the duration of the retard interval and the time delay period he in the ratio of between about 4 to l and 2 to 1.

Upon opening of a large number of sprinkler heads the flow of water through alarm valve 19 causes clapper 20 to open which in turn opens alarm port 21 to admit water to inlet 23 of flow detector 24 but under relatively low pressure. The pressure available at inlet 23 may also be relatively low when the supply main pressure is low. However, as has been described hereinabove, the reaction time of flow detector 24 is substantially independent of water pressure, with the operating time with 5 p.s.i. being only about two seconds greater than with 200 p.s.i. The contacts 51 of the actuated alarm valve close, due to the operation of the flow detector and switch as has already been described, thereby shunting impedance element 14 and relay 15 picks up. Since this is generally a continuing condition, retard 16 will run through its retard interval to actuate the transmitter.

The foregoing may be considered as the normal or more usual manner in which the sprinkler alarm system is actuated to transmit an alarm. Subsequently, the opened or fused sprinkler heads are replaced, the sprinkler risers and appurtenances are allowed to fill and upon cessation of water flow the flow detector and switch reset and the transmitter is manually or otherwise recycled to its condition of readiness to transmit again.

Assuming that only a relatively small number of )sprinkler heads are opened due to the presence of a fire the system is actuated as before but now due to the relatively small volume of water to be supplied the clapper 20 of the actuated alarm valve 19 may be returned to its seat at intervals shorter than the 60 second retard interval of retard 16. The time delay period provided by switch 41 is selected from experience so as to exceed the longest probable dwell of the clapper on its seat. Consequently, though switch 41 may be returned to its unactuated position (Figure 2) the mercury trapped in chamber 47 by the slow rate of flow possible through aperture 48 maintains contacts 51 closed and retard 16 is'not prevented from running through its interval to actuate the transmitter.

By maintaining the aforementioned ratio between the retard interval and the time delay period the possibility of a transient disturbance in the water supply causing a false alarm is minimized. The retard interval (provided by retard 16) less the time delay period (of switch 41) should preferably provide a time duration longer than the duration of the longest transient disturbance in the water supply. The time delay period should not be so long as. to equal or exceed the interval at which such long duration disturbances occur. It will be appreciated that the aforementioned 60 second retard interval and 20 second time delay period were utilized for illustrative purposes and it is contemplated that flow detector 24 and the associated fast-to-make, slow-to-break switch 41 may be used in installations with widely different intervals and periods. However, the present invention is especially well suited for use in systems'which are known to be subjected periodically to relatively long duration disturbances as occur whena relaing the possibility that the alarm system will fail to react properlyin the case of a fire.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

I claim:

1. In a sprinkler alarm system for use with a water sprinkler system through which water normally flows upon the occurrence of a fire, transmitting means adapted to transmit a fire alarm signal, flow detector means, means for connecting said flow detector means into said sprinkler system whereby during flow of water into said system water isled into said flow detector means, fast-to-make, slow-to-break switch means adapted to open its contacts following a predetermined delay period after it is shifted from its make position to its break position, said flow detector means normally maintaining said switch means in its break position and being adapted in response to the flow of water thereinto to shift said switch means to its make position, means so connecting the contacts of said switch means to said transmitting means that the latter is responsive to closing of said contacts, and means for retarding actuation of said transmitting means following closing of said contacts for a retard interval greater than said delay period.

2. In a sprinkler alarm system for use with a water sprinkler system through which water normally flows upon the occurrence of a fire, transmitting means adapted to transmit a fire alarm signal, flow detector means comprising a housing having an inlet communicating with a float chamber formed therein having a predetermined volume and a float member in said chamber and occupying a volume less than but substantially equal to said predetermined volume, means for connecting said flow detecv tor means into said sprinkler system whereby during flow of water into said system water is led into said float chamber, fast-to-make, slow-to-break switch means adapted to open its contacts following a predetermined delay period after it is shifted from its make position to its break position, means whereby said float member normally maintains said switch means in its break position and adapted in response to the flow of water thereinto to shift said switch means to its make position, means so connecting the contacts of said switch means to said transmitting means that the latter is responsive to closing of said contacts, and means for retarding actuation of said transmitting means following closing of said contacts for a retard interval greater than said delay period.

3. A buoyancy type water flow detector, comprising a housing having an inlet communicating with a float chamber formed therein and with said float chamber having a predetermined volume, a float member in said chamber and occupying a volume less than but substantially equal to said predetermined volume, said housing having a base with a normally open outlet drain formed therein, said drain having a capacity which is small compared to that of said inlet, and valve means connected to said float member and adapted to obstruct more or less said inlet in accordance as said float member rises or falls with the level of water in said chamber.

4. A buoyancy type water flow detector comprising a housing having a float chamber formed therein with a pre determined volume, said housing having a base with a plug chamber formed therein'communicating said float chamber and having an inlet communicating-with said plug chamber, means providing communication gbetween the bottom of said plug chamber and the bottom ,of said float chamber, a float member vertically movable: in said float chamber in response to the rise and fall of the level of water in said float chamber, and occupying a volume less than but substantially equal to said predetermined volume, a valve body connected to said. float member and movable vertically therewith, said v valve body being adapted to obstruct more or less said inlet in ac; cordance with its vertical position in said plug chamber, and said base having a normally open outlet drain formed therein having a capacity which is small compared to that of said inlet.

5. A buoyancy type water flow detector comprising a housing having a float chamber formed therein with a predetermined volume, said housing having a base with a plug chamber formed therein communicating with said float chamber and having an inlet communicating with said plug chamber, means providing communication between the bottom of said plug chamber and the bottom of said float chamber, a float member vertically movable in said float chamber in response to the rise and fall of the level of water in said float chamber and occupying a volume less than but substantially equal to said predetermined volume, a valve body connected to said float member and movable vertically therewith, said valve body having a bore formed therein having one opening intermediate the ends of said valve body and presented toward said inlet and another opening presented toward the floor of said plug chamber, said valve body having a plug portion on one side of said one opening adapted to obstruct more or less said inlet in accordance with its vertical position in said plug chamber, and said base having a normally open outlet drain formed therein having a capacity which is small compared to that of said inlet.

6. A buoyancy type water flow detector comprising a housing having a float chamber formed therein with a predetermined volume, said housing having a base with a plug chamber formed therein communicating with said float chamber and having an inlet communicating with said plug chamber, said base having a filling bore formed therein with one end thereof opening into the bottom of said float chamber and the other end thereof opening into the bottom of said plug chamber, a float member vertically movable in said float chamber in response to the rise and fall of the level of water in said float chamber and occupying a volume less than but substantially equal to said predetermined volume, a valve body connected to said float member and movable vertically therewith, said valve body having a bore formed therein having one opening intermediate the ends of said valve body and presented toward said inlet and another opening presented toward said other end of the filling bore, said valve body having a plug portion on one side of said one opening adapted to obstruct more or less said inlet in accordance with its vertical position in said plug chamber, and said base having a normally open outlet drain formed therein having a capacity which is small compared to that of said inlet.

7. A buoyancy type water flow detector comprising a housing having a float chamber formed therein with a predetermined volume, said housing having a base with a plug chamber formed therein communicating with said float chamber and having an inlet communicating with said plug chamber, said base having a filling bore formed therein with one end thereof opening into the bottom of said float chamber and the other end thereof opening into the bottom of said plug chamber, a float member vertically movable in said float chamber in response to the rise and fall of the level of water in said float chamber and occupying a volume less than but substantially equal to said predetermined volume, a valve body connected to said float member and movable vertically therewith,-said valve body having a bore formed therein having one opening intermediate the ends of said valve body and presented toward said inlet and another opening presented toward said other end of the filling bore, said valve body having a plug portion on one side of said one opening adapted to obstruct more or less said inlet ingaccordance with its vertical position in said plug chamber, said base having a normally open outlet drain formed therein having a capacity which is small compared to that of said inlet, and a deflector intermediate said one end of said filling bore and said float member;

References Cited in the file of this patent UNITED STATES PATENTS Milliken Nov. 29,

Hamilton May 14,

Stonier Feb. 17,

Tyden June 13,

FOREIGN PATENTS Great Britain Oct. 1,