US3714988A - Additive injection system - Google Patents

Abstract

AN INJECTION APPARATUS FOR INTRODUCING AN ADDITIVE INTO A FLUID LINE FEEDING FIXED FIRE EXTINGUISHING SYSTEM TO FORM AN ABLATIVE EXTINGUISHANT THEREIN. A PUMP IS PROVIDED WHICH IS DRIVEN BY A HYDRAULIC MOTOR USING THE FLUID AS A DRIVING MEDIUM, AND A SERVOMECHANISM CONTROLS THE MOTOR TO INSURE INJECTION RATES CORRESPONDING TO FLOW RATES OF WATER IN THE LINE. THE APPARATUS INCLUDES A DEVICE FOR STOPPING THE INCREASE OF THE INJECTION WITH INCREASING FLOW RATES AFTER A PREDETERMINED FLOW RATE IS ATTAINED.

Description

Feb. 6, 1973 w. L. LIVINGSTON ADDITIVE INJECTION SYSTEM Filed March 18, 1971 INVENTOR WILLIAM L. LIVINGSTON United States Patent 3,714,988 ADDITIV E INJECTION SYSTEM William L. Livingston, Sharon, Mass, assignor to Factory Mutual Research Corporation, Norwootl, Mass. Filed Mar. 18, 1971, Ser. No. 125,635 Int. Cl. A620 35/100 US. Cl. 169-13 8 Claims ABSTRACT OF THE DISCLOSURE An injection apparatus for introducing an additive into a fluid line feeding a fixed fire extinguishing system to form an ablative extinguishant therein. A pump is provided which is driven by a hydraulic motor using the fluid as a driving medium, and a servomechanism controls the motor to insure injection rates corresponding to flow rates of water in the line. The apparatus includes a device for stopping the increase of the injection with increasing flow rates after a predetermined flow rate is attained.

BACKGROUND OF THE INVENTION This invention relates to an additive injection system and, more particularly, to a system for automatically injecting a gelling additive into a fluid line to produce a fire extinguishant in the form of an ablative gel for supply to thermally actuated sprinkler heads in a fixed fire extinguishing system.

In a copending application entitled Method of Controlling Fire, Ser. No. 776,475, filed Oct. 10, 1968, now abandoned, by William L. Livingston and Russell W. Pierce and assigned to the assignee of the present invention, a method of fire protection is disclosed in which a gelling agent in the form of a water swellable polymer is injected into a flowing stream of water supplying the sprinkler heads of a fixed extinguishing system upon actuation of the heads, to put out a fire in the enclosure protected by the system. The ablative gel has excellent thermal absorption characteristics and, equally as important, is highly viscous and thus tends to cling to the surfaces on which it is sprayed. As a result, a relatively low quantity of ablative extinguishant is required to put out a fire, thereby enabling the system to be designed with a low flow capacity. Also, the ablative gel reduces the water damage to the space being protected.

In a copending application entitled Additive Injection System, Ser. No. 864,757 filed Oct. 8, 1969, now Pat. No. 3,642,072, by William L. Livingston and assigned to the assignee of the present invention, a system is disclosed which is adapted to inject the additive into the water line in an efiicient and reliable manner. In general, this system employs a hydraulic motor driven by water tapped at line pressure from the main conduit supplying the fire extinguishing system. Water is supplied to the motor through a control valve operated by a servomechanism controlled by a sensing device responsive to water flow in the system feed conduit. The motor drives an injection pump by which the additive is introduced into the flowing line in direct proportion to the water flow rate through the line.

Although this system proved to be extremely effective in its injection operation and resulted in a uniform additive-water mixture, it was discovered that, after a predetermined flow rate had been obtained, any additional increase in the additive injection rate with further increases in the water flow rate would not materially enhance the fire fighting properties of the mixture. The latter, of course, is unsatisfactory from an economic standpoint and, in addition, creates the possibility of too high an additive-water ratio to carry out the complete design goals of the system.

3,714,988 Patented Feb. 6, 1973 SUMMARY on THE INVENTION It is therefore an object of the present invention to provide an additive injection apparatus for a fixed fire extinguishing system in which the advantages of the injection of additive into the system are maintained, while the increase of additive injection with increasing flow rates is terminated after a predetermined flow rate is obtained.

Toward the fulfillment of this and other objects, the system of the present invention comprises at least one discharge head adapted to be thermally actuated by fire temperatures to disperse an extinguishant, a conduit for supplying fluid to said head, injection means for introducing an additive to said conduit in direct proportion to the fluid flow therethrough, and means to terminate the increase of additive injection after a predetermined fluid fiow rate is attained.

BRIEF DESCRIPTION OF THE DRAWING Reference is now made to the accompanying drawing for a better understanding of the nature and objects of the present invention. The drawing illustrates the best mode presently contemplated for carrying out the objects of the invention and is not to be construed as a restriction or limitation on its scope. The drawing is a schematic view illustrating the additive injection system of the present invention employed in a fixed fire extinguishing system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawing, the injection apparatus of this invention is generally designated by the reference numeral 10 and is incorporated in a fixed fire extinguishing system including a main feed conduit 12 connected by means of a T-coupling 14 to a riser 116. In accordance with conventional practice, the riser 16 extends upwardly to one or more branch lines 18 having a plurality of nozzles or sprinkler heads 20' depending therefrom. Also in accordance with conventional practice, each of the heads 20 is provided with temperature responsive release means 21 so that upon the development of a fire in the vicinity of one or more of the heads, the system is activated automatically to supply water from the main conduit 12 through the riser 16, the branch line 18 and out of the heads 20.

Although the specific details of each component of the injection apparatus 10 have been omitted from FIG. 1 for the convenience of presentation, the general organization of the apparatus is shown to include a storage tank 22 for a gel additive slurry preferably of the type described above. The tank 22 is connected at .its lower end by means of a discharge conduit 24 to the intake 26 of a peristaltic pump 28. The latter pump is described in detail in the above application Ser. No. 864,757 and has a discharge tube 30 which is coupled by a reducer 32 to the T-coupling 14. At the opposite end of the pump 28 from the tube 30 is a gear box and bearing assembly 34 for transmitting torque from an input shaft 36 which, in turn, is drivably connected to a hydraulic motor 38 by a motor output shaft 40 and a slip-impact clutch 42.

The motor 38 is preferably of a positive displacement piston type designed to develop full torque at low speeds and is in communication with the main conduit 12 by way of a tap line 44 having a control valve 46 connected therein. An exhaust pipe 48 is provided on the motor 38 and is connected to a drain system, or the like (not shown). A differential pressure regulator 50 is connected in the line 44 upstream of the control valve 46 and has a flow sensing line 51 connected in the line 44 downstream of the control valve. Further details of the regulator 50 will be described later.

As a result of the above arrangement, the introduction of water under line pressure into and through the line 44,

the regulator 50, the valve 46, the motor 38, and out through the exhaust pipe 48, will effect rotation of the motor and correspondingly drive the output shaft 40 at speeds controlled by the valve 46 in a manner well known to those familiar with such motors.

Because of the high reactive character of the contemplated additive, it is imperative that the rate of injection be controlled in a manner to avoid overinjection and preferably by means having an underinjection or no-injection failure mode. To this end, a servomechanism is provided to regulate the control valve 46 to insure that the pump 28 will be operated in conformity to flow rates in the conduit 12. The servomechanism includes a flow-responsive device in the form of a rotatable screw 52 supported in the main conduit 12. Rotation of the screw 52 is transmitted by means, including a shaft 54, to one end input of a conventional differential gear 56 having output ring gear 58. The shaft 54 is connected to the sensing screw 52 by a one-way torque transmitting device such as a clutch 60, so that the shaft 54 may be rotated by the screw 52 while rotation of the screw by the shaft 54 is prevented. The other end of the differential 56 is connected by a servoshaft 62 to a similar one-way torque transmitting device 64 on the motor 38.

As a result of the above arrangement, the ring gear 58 will be driven in accordance with the differential input from the shafts 54 and 62. The ring gear 88 is in mesh with a gear 66 keyed to one end of a shaft 68 connected at its opposite end with the valve 46. Hence, with the shaft 62 stationary, rotation of the screw 52 as a result of water fiow through the main conduit 12 will effect rotation of the shaft 54 to develop a differential output rotation of the ring gear 58. The ring gear 58 in turn rotates the gear 66 and shaft 68 to open the valve 46. The valve 46 is preferably of the type having an inherent bias toward the open position to bring about an opening movement with a minimum of torque delivered to the shaft 68.

As a result of the above, when the servoshaft 62 rotates faster than the shaft 54 as a result of a sudden reduction of the fiow rate sensed by the screw 52, for example, the output ring gear 58, and therefore the gear 66 and shaft 68 will be driven in a direction to close the valve 46 and slow down the motor 38 to rotational speeds correlated directly to that of the screw 52. inasmuch as the screw 52 is rotated at a rate corresponding directly to the flow rate of water through the main conduit 12, it becomes apparent that the motor 38, and therefore the pump 28, is regulated to operate at speeds directly proportional to the flow rate of water through the main conduit 12.

As sated above, it has been discovered that the injection of the additive at a rate directly proportional to the Water flow rate as sensed by the screw 52 results in a satisfactory additive-Water ratio within a predetermined range of water flow rates. However, after the upper limit of this water flow rate range is exceeded, it becomes desirable to terminate the increase of additive injection with increases in the water flow rate. To this end, the differential pressure regulator 50 is empolyed to control the pressure differential across the valve 46. The regulator 50 may be of a conventional design and in general, comprises a spring-loaded modulating valve member (not shown) cooperating with a valve seat disposed in the line 44. The valve member is adapted to act against the pressure in the upstream portion of the line 44 and the flow sensing line 51 is connected to the regulator 50 at a point whereby it also acts against this pressure.

The above-mentioned spring loaded valve member can be adjusted so that the pressure upstream of the valve 46 will be such that the pressure differential across the valve will not exceed a predetermined value. Since the fiow through the valve 46 in its full open position will be directly proportional to the pressure, and since the latter is regulated by the regulator 50, it follows that once the valve 46 is completely opened and the predetermined maximum pressure differential across the valve is reached,

any additional increases in the water flow through the valve will be terminated despite further increases in the water pressure and in the flow rate in the conduit 12- This, of course, establishes an upper limit that the speed of the motor 38, and therefore the pump 28 can attain, and terminates the increase of the additive injection after a predetermined water flow rate is reached.

Summarizing the operation of the entire system of the present invention, it will be apparent that upon the opening of any one of the heads 20, water will pass through the main conduit 12, thus rotating the screw 52 and opening the valve 46 by Way of the differential 56 as described above. As soon as the motor 38 has developed its operating output torque, the shaft 40 will be coupled with the drive shaft 36 of the pump 28 by way of the slip-impact clutch 42 to initiate rotation of the pump rotor. The gel additive slurry, which is passed by gravity from the tank 22 through the discharge pipe 24 into the pump feed chamber 26, will be pumped through the tube 30 and into the riser 16 to be mixed with the flowing stream of water.

As soon as the servomechanism moves the valve 46 to a fully opened position and as soon as a predetermined pressure differential is established across the valve, the regulator 50 comes into operation by limiting any further water flow through the valve by virtue of maintaining the predetermined pressure differential across the valve, as described above. As a result, once a predetermined flow rate through the conduit 12 has been attained, there will be no further increases in additive injection in direct proportion to any further increases in the flow rates.

As emphasized above, this provides for an efficient use of the additive, which is especially advantageous in the situation where a large fire sets off several of the heads 20 thus causing increased water flow rates through the system. Also, it has been discovered that the differential pressure regulator 50 also improves the operation of the valve 46 by reducing its sensitivity.

It is understood that the other components disclosed in the above application Ser. No. 864,757, but not described above, may be incorporated in the system of the present invention. For example, a baffle or eddy plate can be disposed in the conduit 16 to achieve uniform mixing of the additive with the flowing stream of water. As disclosed in the above application, this eddy plate is preferably formed of material which is flexible so that under conditions where the gel is being introduced, thereby developing lower system flow rates due to the formation of the ablative fluid extinguishant in the system, the eddy plate functions to develop the necessary mixing flow paths and turbulence. Where, however, the injection system fails upon the demand for extinguishant by the heads in the fire extinguishing system, significantly greater flow rates are required by the system as a result of the relatively low viscosity of plain water. The eddy plate responds to these greater flow rates by flexing so that the increased flow rates needed by the heads of the system are not impeded by the eddy plate.

Also, a frangible cap may be provided over the open end of the pump 28 to provide a positive seal between the additive and water within the conduit 12 in order to prevent inadvertent discharge of the additive into the riser 16, as specifically disclosed in the above application Ser. No. 864,757.

It is contemplated that numerous variations may be made in the injection apparatus depicted by the disclosed embodiment, which variations fall within the scope of the present invention. As an example of the variations, other means may be provided to stop the increase of additive injection with increasing flow rates after a predetermined flow rate has been attained. For example, the pump 28 may be provided with a governor, or an overspeed clutch may be provided which is connected to the pump so that once a predetermined pumping speed is attained, it will not be increased. Also, although water and a water swellable gelling agent were disclosed above as examples of a fluid and an additive which together form an extinguishant, it is contemplated that other fluids and additives may be utilized in the system of the present invention Without departing from the scope thereof.

Of course, still another ariations of the specific construction and arrangement of the additive injection system disclosed above can be made by those skilled in the art Without departing from the invention as defined in the appended claims.

I claim:

1. A fixed fire extinguishing system comprising at least one discharge head adapted to be actuated by a fire condition to disperse an extinguishant, a conduit for supplying fluid to said head, a pump having intake means to receive an additive and discharge means for discharging said additive into said conduit, a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, valve means connected in said conduit upstream of said motor for controlling the fluid flow rate through said conduit, and means connected in said conduit for limiting the maximum fluid pressure diflerential occurring across said valve means to terminate the increase of additive injection after a predetermined fluid flow rate is attained.

2. A fixed fire extinguishing system comprising at least one discharge head adapted to be actuated by a fire condition to disperse an extinguishant; a conduit for supplying fluid to said head; a pump having intake means to receive an additive and discharge means for discharging said additive into said conduit; a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit; valve means connected in said conduit upstream of said motor for controlling the fluid flow rate through said conduit; sensing means for sensing the extinguishant flow rate through said conduit upstream of said valve means; servo means having first input means connected to the output of said sensing means, second input means connected to said motor, and output means driven by the differential of said first and second input means and connected to said valve means; and means to terminate the increase of additive injection after a predetermined fluid flow rate is attained.

3. An apparatus for forming an extinguishant in a conduit containing fluid for distribution to at least one discharge head, said apparatus comprising a pump having intake means to receive an additive and discharge means for discharging said additive into said conduit; a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, valve means connected in said conduit upstream of said motor for controlling the fluid flow through said conduit, and means connected in said conduit for limiting the maximum fluid pressure differential occurring across said valve means to terminate the increase of additive injection after a predetermined fluid flow rate is attained.

4. An apparatus for forming an extinguishant in a conduit containing fluid for distribution to at least one discharge head, said apparatus comprising a pump having intake means to receive an additive and discharge means for discharging said additive into said conduit; a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit; valve means connected in said conduit upstream of said motor for controlling the fluid flow rate through said conduit; sensing means for sensing the extinguishant flow rate through said conduit upstream of said valve means; servo means having first input means connected to the output of said sensing means, second input means connected to said motor, and output means driven by the diflerential of said first and second input means and connected to said valve means; and means to terminate the increase of additive injection after predetermined fluid flow rate is attained.

5. A fixed fire extinguishing system comprising at least one discharge head adapted to be actuated by a fire condition to disperse an extinguishant, a conduit for supplying fluid to said head, a pump having intake means to receive an additive and discharge means opening into said conduit, drive means to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, and means for limiting the maximum output of said drive means in response to the fluid flow in said conduit reaching a predetermined rate to automatically terminate the proportional increase of additive injection.

6. A fixed fire extinguishing system comprising at least one discharge head adapted to be actuated by a fire condition to disperse an extinguishant, a conduit for supplying fluid to said head, a pump having intake means to receive said additive and discharge means opening into said conduit, a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, and means for limiting the amount of fluid applied to said motor in response to the fluid flow in said conduit reaching a predetermned rate to automatically terminate the proportional increase of additive injection.

7. An apparatus for forming an additive-fluid mixture in a conduit having fluid flowing therethrough, said ap paratus comprising a pump having intake means to receive an additive and discharge means opening into said conduit, drive means to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, and means for limiting the maximum output of said drive means in response to the fluid flow in said conduit reaching a predetermined rate to automatically terminate the proportional increase of additive injection.

8. An apparatus for forming an additive-fluid mixture in a conduit having fluid flowing therethrough, said apparatus comprising a pump having intake means to receive an additive and discharge means opening into said conduit, a hydraulic motor connected to said conduit and driven by said fluid to drive said pump to inject said additive into said conduit in proportion to the fluid flow through said conduit, and means for limiting the amount of fluid applied to said motor in response to the fluid flow in said conduit reaching a predetermined rate to automatically terminate the proportional increase of additive injection.

References Cited UNITED STATES PATENTS 2,580,011 12/1951 Freeman 169-15 2,543,941 3/1951 Sargenit 169-15 2,164,153 6/1939 Friedrich 169-15 X 2,374,516 4/ 1945 Wendell 169-15 2,567,997 9/1951 Granberg 169-15 X M. HENSON WOOD 111., Primary Examiner R. W. THIENE, Assistant Examiner US. Cl. X.R. 169-15, 16

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