Abstract:
A building sprinkler system includes a pump having an input for receiving water and an output that is connected to selectively feed a plurality of sprinkler heads. A driver is operatively connected to the pump for driving the pump. A cooling arrangement is provided for cooling the pump during pump testing operations. The cooling arrangement includes: a heat exchanger with a primary loop formed by a flow path for delivering water from the output of the pump through the heat exchanger and back to the input of the pump, and a secondary loop formed by a flow path for delivering coolant from the heat exchanger through a radiator and back to the heat exchanger so that heat is transferred from the water to the coolant via the heat exchanger and from the coolant to air via the radiator.

Description:
CROSS-REFERENCE 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/495,154, filed Jun. 9, 2011, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates to sprinkler systems used for suppressing fires and more particularly to a cooling arrangement for the sprinkler system fire pump. 
       BACKGROUND 
       [0003]    Building (or other facility) sprinkler systems provide pressurized liquid (e.g., water) to extinguish or control a fire. A pump (e.g., a centrifugal pump) is used to provide the water pressure. The pump may be powered by an electric motor or other type of pump driver, such as diesel engine. 
         [0004]    During actual operation in a fire fighting mode, water passing through the pump cools the pump and prevents it from overheating. Applicable code/regulations require that fire pumps must be periodically operated in a test mode to ensure reliability. During the test mode water is not delivered to the building sprinkler system. Instead, a small amount of water is delivered through the fire pump and diverted via a valve to an alternate path. 
         [0005]    When the fire pump is driven, by an electric motor or by a diesel engine that is cooled by an engine mounted radiator (coolant to air) and fan, in pump test mode pressure builds up at the output side of the fire pump opening the alternate path that leads to drain. A small volume of water (e.g., 1-2% of fire pump rated flow) is delivered through the fire pump and then to the drain. 
         [0006]    In the test mod, the small volume of water flow through the fire pump is sufficient for cooling the fire pump. However, the water is wasted by being delivered to the drain. 
       SUMMARY 
       [0007]    In one aspect, a building sprinkler system includes a pump having an input for receiving water and an output that is connected to selectively feed a plurality of sprinkler heads. A driver is operatively connected to the pump for driving the pump. A cooling arrangement is provided for cooling the pump during pump testing operations. The cooling arrangement includes: a heat exchanger with a primary loop formed by a flow path for delivering water from the output of the pump through the heat exchanger and back to the input of the pump, and a secondary loop formed by a flow path for delivering coolant from the heat exchanger through a radiator and back to the heat exchanger so that heat is transferred from the water to the coolant via the heat exchanger and from the coolant to air via the radiator. 
         [0008]    In the foregoing system, flow along the primary loop may be controlled via a valve that opens in response to pressure. The valve may be configured to remain closed under pressure conditions experienced when water is being delivered from the pump to the sprinkler heads, thereby preventing diversion of flow from the sprinkler heads when water flow to the sprinkler heads is needed for firefighting. The valve may be a pressure relief valve that opens when pressure exceeds a set high threshold. 
         [0009]    The primary loop preferably lacks any dump to drain so that water flowing along the primary loop is not wasted. 
         [0010]    In one implementation of the system, the driver is an electric motor, the secondary loop includes an electric motor driven pump for causing coolant flow through the secondary loop, and the radiator includes an electric fan. The electric motor driven pump and the electric fan may be controlled according a temperature of water in the primary loop downstream of the valve. 
         [0011]    In another implementation of the system, the driver is an engine, and the secondary loop includes shared flow through the engine and radiator. Flow of coolant through the secondary loop may be provided by an additional engine coolant pump, flow of coolant from the heat exchanger may be available for flow into the engine, and a thermostat may be located along the secondary loop downstream of the engine, with the heat exchanger is located upstream of the engine. 
         [0012]    The secondary loop may include a bypass flow path provided from the downstream side of the engine to the upstream side of the engine under control of the thermostat. 
         [0013]    The additional engine coolant pump may be located between the output of the radiator and the input of the heat exchanger, and the output of the heat exchanger may feed both a first path into the engine and a second path that bypasses the engine. The first path and the second path may overlap at least in part and a flow restrictor may be located in the second path downstream of a location where the first flow path and the second flow path diverge. 
         [0014]    The engine, heat exchanger and radiator may be configured as a unit, with an end portion of the unit extending through a building wall to place the radiator external of the building and to place the engine and heat exchanger internal of the building, thereby placing air flow requirements for cooling of the radiator outside of the building. 
         [0015]    In another aspect, a method is provided for testing a fire pump of a facility fire suppression system that includes the fire pump, a fire pump driver and a plurality of sprinkler heads. The method involves: operating the fire pump driver to deliver water through the fire pump while maintaining a flow path from the fire pump to the sprinkler heads in a closed condition; responsive to pressure build-up at the output side of the fire pump, opening a flow path from the output side, to and through a heat exchanger and back to the input side of the pump to circulate water without wasting water; and providing a secondary flow path for coolant fluid from the heat exchanger to a radiator and back to and through the heat exchanger for transferring heat from the water to the coolant via the heat exchanger and for transferring heat from the coolant to air via the radiator. 
         [0016]    In the subject method, the fire pump driver may be an engine and the secondary flow path from the heat exchanger may include both a first path from the heat exchanger, through the engine and to the radiator and a second path from the heat exchanger to the engine without passing through the engine. The first path and the second path may overlap at least in part and a flow restrictor is located in the second path downstream of a location where the first flow path and the second flow path diverge. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic depiction of one embodiment of a fire suppression sprinkler system with fire pump cooling arrangement where the fire pump is driven by an electric motor; and 
           [0018]      FIG. 2  is a schematic depiction of another embodiment of a fire suppression sprinkler system with fire pump cooling arrangement where the fire pump is driven by a diesel engine with radiator cooling; 
           [0019]      FIG. 3  is a schematic of a frame mounted unit with radiator external of a building wall and engine and heat exchanger internal of the building wall. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring to  FIG. 1 , an exemplary sprinkler system  10  with fire pump cooling arrangement is shown. System  10  includes a fire pump  12  driven by an electric motor  14  (the connection between the two shown schematically at  16 ). The input side  18  of the fire pump is connected to source water  20  via a valve  22 . The output side  24  of the fire pump is connected via a valve  28  to a sprinkler arrangement  26  that may be made up of numerous pipes  30  and numerous associated fire sprinkler nozzles  32 , each of which typically has an associated temperature sensitive valve that opens only in the presence of a high temperatures as may be caused by a fire event. Valves  22  and  28  may be, for example, manually operated valves that are maintained in respective open positions at all times when the sprinkler system is in the stand-by mode in the event the sprinkler system needs to be operated for fire suppression. During a fire suppression/extinguishing operation, the motor  14  is operated to drive the fire pump  12  and valves  22  and  28  are open so that water flows freely through the system and out through one or more of the nozzles  32 . 
         [0021]    During test mode operation, the motor  14  is operated to drive the fire pump, but there is no flow out of any of the nozzles because the nozzles are temperature controlled and do not open except in the presence of a high temperature. This condition of no nozzle flow is called shut-off. This results in a pressure build-up (called rise to shutoff) at the output side  24  of the fire pump that is higher than the output side pressure produced during delivery of water to the sprinkler arrangement  26  when fire fighting. This high pressure causes a pressure relief valve  34  to open, delivering water through a liquid to liquid (e.g., water to freeze protected water) heat exchanger  36  via flow path  38  and then back to the input side  18  of the fire pump via flow path  40 . This path makes up a primary loop of the heat exchanger. During fire extinguishing operation the fire pump output pressure is lower than during shutoff, and the pressure valve  34  remains closed. 
         [0022]    The cooling arrangement includes a secondary loop from the heat exchanger  36  via flow path  42  to a radiator  44  and back to the heat exchanger  36  via flow path  46 . Flow of freeze protected water (e.g., water with anti-freeze) in the secondary loop is provided by an electric motor driven pump  48  along flow path  46 . The radiator  44  is located externally of the building or facility (shown by dashed line  50 ) in which the sprinkler system is installed and includes an electric fan  52  that is operated to provide air flow through the radiator to transfer heat from the coolant fluid in the secondary loop to ambient air. Electrical power to the pump  48  and fan  52  are provided from the same emergency power source that powers the fire pump motor  14  to ensure the cooling system operates properly anytime the fire motor operates. 
         [0023]    The pump  48  and fan may be controlled by use of separate or common thermostatic sensors, preferably located downstream of the pressure relief valve  34  (e.g., per sensor  54 ). When the sensor  54  indicates a high temperature condition during a testing operation, the pump  48  and fan  52  are turned on to operate the secondary loop of the cooling arrangement. In an energy conservation example, the pump  48  only may be initially turned on when the sensor  54  indicates a first threshold high temperature and the fan  52  may also be turned on only if and when the sensor  54  indicates a second threshold high temperature that is higher than the first threshold high temperature. An exemplary controller  60  is shown schematically, which could be made up of control circuits, programmed processors and/or combinations of the same to control and run each of the motor  14 , pump  48  and fan  52 . 
         [0024]    Referring now to  FIG. 2 , another exemplary sprinkler system  70  with fire pump cooling arrangement is shown. System  70  includes a fire pump  12  driven by an diesel engine  72  (the connection between the two shown schematically by dashed line  74 ). The input side  18  of the fire pump is connected to source water  20  via a valve  22 . The output side  24  of the fire pump is connected via a valve  28  to a sprinkler arrangement  26  that may be made up of numerous pipes (as per the embodiment of  FIG. 1 ). During a fire fighting operation, the engine  72  is operated to drive the fire pump  12  and valves  22  and  28  are opened so that water flows freely through the system and out through one or more of the nozzles  32 . 
         [0025]    During test mode operation of the system the engine  72  is operated to drive the fire pump, but there is no flow out of any of the nozzles, which remain closed except under high temperature. This condition is called shut-off. This results in a pressure build-up (called rise to shutoff) at the output side  24  of the fire pump that is higher than the output side pressure produced during delivery of water to the sprinkler arrangement  26  when fire fighting. This high pressure causes a pressure relief valve  76  to open, delivering water through a liquid to liquid (e.g., water to coolant water) heat exchanger  78  via flow path  80  and then back to the input side  18  of the fire pump via flow path  82 . This path makes up a primary loop of the heat exchanger. 
         [0026]    The cooling arrangement includes a secondary loop from the heat exchanger  78  via flow path  84  and  95  to the input of the engine coolant pump  86 . The output of the pump  86 , as is typical of engines, provides pressurized flow of coolant through the engine  72  and out to the engine thermostat  94 . Thermostat  94 , as is typical of engines, regulates the coolant flow along either path  97  to the radiator  88  or path  92 , a bypass back to the pump  86  suction, according to the temperature of the coolant in the engine  72 . In the embodiment of  FIG. 2 , the heat exchanger  78  is inserted into the engine&#39;s cooling supply circuit, between the outlet of radiator  88  and the coolant pump  86 , to form the secondary loop of the cooling system. To overcome the added pressure drop of freeze protected water (e.g., water with anti-freeze) in the secondary loop through heat exchanger  78 , and provide adequate flow available to pump  86 , pump  99 , driven by the engine  72  (the connection between the two shown schematically by line  100 ), or alternatively electric motor driven, is inserted into path  90  to provide flow in the secondary loop. When the engine thermostat  94  is closed and secondary water is flowing via bypass  92  back to pump  86  suction, secondary loop flow provided by pump  99  will exit heat exchanger  78  via flow path  84  which connects with flow path  97  and flows to the radiator  88 . When the engine thermostat  94  is open and secondary water is not flowing via bypass  92  back to pump  86  suction, the secondary loop flow is via path  97  back to the radiator  88 . Also, during open thermostat  94  operation the suction requirement of pump  86  is provided via flow path  95  connected to flow path  84 . A positive suction pressure is provided in flow path  95  by pump  99  (which has a greater flow than pump  86 ) at pump  86  by a restrictor  101  inserted in flow path  84  downstream of the connection with flow path  95 . The temperature rise of the fire pump and engine will be more uniform during periods of warm-up operation using the illustrated configuration. 
         [0027]    The radiator  88  may be located internally of the building or externally of the building or facility in which the sprinkler system  26  is installed and includes a fan  98  that is driven by the engine  72  so as to flow ambient air through the radiator to transfer heat from the coolant fluid in the secondary loop to ambient air. 
         [0028]    In one implementation, the system of  FIG. 2  is constructed with a through wall engine mounted radiator. Specifically, with reference to  FIG. 3 , the engine  72 , heat exchanger  78  and radiator are all constructed as a unit (e.g., on a common frame  110 ). The radiator  88  is mounted at one end of the unit frame so that the radiator can be located external of the a wall  112  of the building or facility and the engine  72  and heat exchanger  78  can be installed internal of the building or facility. 
         [0029]    It is to be clearly understood that the above description is intended by way of illustration and example only and is not intended to be taken by way of limitation, and that changes and modifications are possible. Accordingly, other embodiments are contemplated and modifications and changes could be made without departing from the scope of this application.