Abstract:
A discharge assembly used with a fire suppression delivery system comprises a nozzle having an outer nozzle surface and inlet and discharge ends. The inlet end receives fire suppression agent and the discharge end dispenses fire suppression agent through an orifice. A blow-off cap has an open-ended cavity shaped to receive the discharge end of the nozzle and cover the orifice. The cavity includes an interior cap surface located in close proximity to the outer nozzle surface of the nozzle when the blow-off cap is mounted on the discharge end of the nozzle. A receptacle is formed in at least one of the outer nozzle surface of the nozzle and the interior cap surface of the blow-off cap. A retention element fits within the receptacle and engages the outer nozzle surface and interior cap surface, providing a predetermined amount of retention resistance to retain the blow-off cap on the nozzle.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The application relates to and claims priority from provisional patent application Ser. No. 60/683,673, titled “CB BLOW-OFF CAP”, filed May 23, 2005, the complete subject matter of which is expressly hereby incorporated herein in its entirety. 

   BACKGROUND OF THE INVENTION 
   This invention relates generally to fire suppression systems used in buildings, restaurants and other commercial kitchens, and more particularly, to blow-off caps used on nozzles within the fire suppression systems. 
   Fire suppression systems provide an integral service to commercial kitchens, which use multiple cooking appliances (e.g. chain broilers, deep fryers, broilers, cook tops, and the like) to cook large quantities of food. The cooking appliances are often operated at high temperatures for extended periods of time, creating a large amount of grease and other effluent. 
   Fire suppression components are located over the top of the cooking appliances, aimed inside partially enclosed cooking appliances, and are within hoods and ducts associated with the exhaust system. When a hazardous condition is detected, a fire suppression agent is discharged through a nozzle to eliminate the hazardous condition. The fire suppression agent may be, for example, a chemical agent, water, or a combination of the two. 
   Due to the large amount of effluent present in the location of the nozzles, clogging of the orifice or orifices through which the fire suppression agent is discharged needs to be prevented so that the system activates correctly when needed. A cap is therefore affixed to the nozzle. The cap is to be blown or pushed off the nozzle, or broken or burst, by the pressure created when fire suppression agent is discharged. 
   A silicone rubber cap has been used to cover the end of the nozzle. However, the rubber cap deteriorates due to effluent build up and the high temperature experienced in the exhaust area over broilers and other cooking units. A brass cap held onto the nozzle with a retaining clip has also been used. The retaining clip weakens over time due to, for example, the extreme temperature gradients, allowing the cap to fall off the nozzle. Also, grease accumulates inside the cap and nozzle, effectively freezing the cap onto the nozzle and/or clogging the orifice. 
   Therefore, a need exists for a blow-off cap and nozzle assembly capable of withstanding the extreme conditions experienced in commercial kitchen applications, while still allowing the blow-off cap to be pushed off the nozzle during a fire discharge situation. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth_below. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In one embodiment, a discharge assembly for use with a fire suppression delivery system comprises a nozzle having an outer nozzle surface. The nozzle also has an inlet end configured to receive a fire suppression agent and a discharge end with an orifice therein to dispense the fire suppression agent in a desired manner. A blow-off cap has an open-ended cavity shaped to receive the discharge end of the nozzle and to cover the orifice. The cavity includes an interior cap surface that is located in close proximity to the outer nozzle surface of the nozzle when the blow-off cap is mounted on the discharge end of the nozzle. A receptacle is formed in at least one of the outer nozzle surface of the nozzle and the interior cap surface of the blow-off cap. A retention element is fit within the receptacle and engages the outer nozzle surface and the interior cap surface to provide a predetermined amount of retention resistance to retain the blow-off cap on the nozzle. 
   In another embodiment, a blow-off cap for use on a nozzle in a fire suppression system comprises a cover and an O-ring. The nozzle has an outer nozzle surface and inlet and discharge ends. The inlet end is configured to receive a fire suppression agent and the discharge end has an orifice therein to dispense the fire suppression agent in a desired manner. The cover of the blow-off cap comprises a cavity configured to receive the discharge end of the nozzle. The O-ring is fixed within the cavity and is snappingly received over the outer nozzle surface. The O-ring and nozzle provide resistance to retain the blow-off cap on the nozzle until a system pressure builds up sufficient to push the blow-off cap off the nozzle. 
   In another embodiment, a fire suppression system comprises a fire suppression delivery system for delivering fire suppression agent. A nozzle has an outer nozzle surface and inlet and discharge ends. The inlet end is configured to receive the fire suppression agent and the discharge end has an orifice therein to dispense the fire suppression agent in a desired manner. A blow-off cap has an open-ended cavity shaped to receive the discharge end of the nozzle and to cover the orifice. The cavity includes an interior cap surface that is located in close proximity to the outer nozzle surface of the nozzle when the blow-off cap is mounted on the discharge end of the nozzle. A receptacle is formed in at least one of the outer nozzle surface of the nozzle and the interior cap surface of the blow-off cap. A retention element is fit within the receptacle and engages the outer nozzle surface and the interior cap surface to provide a predetermined amount of retention resistance to retain the blow-off cap on the nozzle. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a fire suppression delivery system and a chain broiler needing overhead broiler protection. 
       FIG. 2  illustrates an alternative fire suppression delivery system and an appliance line. 
       FIG. 3  illustrates a cross-section of a cover of the blow-off cap in accordance with an embodiment of the present invention. 
       FIG. 4  illustrates a view of the blow-off cap with a retention element installed within the cover in accordance with an embodiment of the present invention. 
       FIG. 5  illustrates a side view of the nozzle in accordance with an embodiment of the present invention. 
       FIG. 6  illustrates the discharge end of the nozzle in accordance with an embodiment of the present invention. 
       FIG. 7  illustrates a side view of the cap receiving portion of the nozzle in accordance with an embodiment of the present invention. 
       FIG. 8  illustrates a cross-section of the blow-off cap having an interconnected lanyard in accordance with an embodiment of the present invention. 
       FIG. 9  illustrates a cross-section of an assembly of the blow-off cap and the nozzle in accordance with an embodiment of the present invention. 
       FIG. 10  illustrates the nozzle and the blow-off cap in accordance with an embodiment of the present invention. 
   

   The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. It should be understood that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a fire suppression delivery system  101  and a chain broiler  100  needing overhead broiler protection. The chain broiler  100  has a chain  102  or other moving belt with a surface  108  which is moved laterally between a top broiler unit  104  and a bottom broiler unit  106 . The surface  108  of the chain  102  may be accessed through an access window  110  on a first end  112  of the chain broiler  100 . The chain  102  moves a food item placed on the surface  108 , such as a hamburger or piece of chicken, from the first end  112  to a second end  114  of the chain broiler  100 , cooking the food item with the top and bottom broiler units  104  and  106 . The food item is removed at the second end  114  through a second access window  116 . The chain broiler  100  has an outer cover  118  which retains heat, protects users from burns, grease spatters and effluent, and provides a barrier between the environment and the components of the chain broiler  100 . 
   The chain broiler  100  has an open or substantially open top end  120  to exhaust effluent. The open top end  120  is placed beneath an exhaust hood  122 , which is connected to an exhaust duct within an exhaust system. The exhaust system may provide ventilation for multiple areas within a kitchen, such as additional hoods, chain broilers, upright broilers, ovens and the like. 
   The fire suppression delivery system  101  uses a number of interconnected controls, panels, pipes, tanks, bottles, nozzles, blow-off caps, detectors and the like. The fire suppression delivery system  101  may be designed based on the cooking appliances it will be used with. A hazard zone, such as a flat, level and/or rectangular surface including all of the cooking hazards of the protected appliances under the hood or hoods, may be defined when designing the number, flow, location and aiming of the nozzles. Fire suppression is provided to the hazard zone as well as to the hood  122  and other locations within the exhaust system. 
   A control unit  124  is located near the hood  122  and provides a control panel  126  to allow operation of the fire suppression delivery system  101 . The control panel  126  may be accessible from the outside of the control unit  124 , or may be behind a door or window. The control panel  126  provides controls to a user, such as an on/off switch  154  and a manual activation switch  156  for manually activating fire suppression. Alternatively, emergency control of the fire suppression delivery system  101  may be provided simply through a manual pull station and a fuel shut off. 
   One or more bottles  128  of fire suppression agent may be installed within the control unit  124 , a separate enclosure, or affixed to a wall or other location. A water source  129  may also be supplied to the fire suppression delivery system  101 . The bottle  128  is connected to a pipe  130 , hose or other conduit suitable for carrying the fire suppression agent and able to withstand hot and fluctuating temperatures. An actuator  168  may be connected to the bottle  128  or between the bottle  128  and the pipe  130 . The pipe  130  extends out of the control unit  124 . The pipe  130  is bent in one or more locations, if necessary, such as at elbow  132 , and extends into the hood  122 . The water source  129  may also be connected to the actuator  168  and allowed to flow through pipe  130 , or may be connected to a second actuator and pipe (not shown) 
   One or more nozzles  134 ,  136  and  138  are interconnected to the pipe  130  and may be positioned uniformly under the hood  122  from the first end  112  of the chain broiler  100  to the second end  114 . The nozzles  134 - 138  are configured to dispense the fire suppression agent through one or more orifices. Each of the nozzles  134 - 138  has a flow rating, angle of coverage, and/or spray pattern, and the type and configuration of nozzles  134 - 138  may vary. For example, both nozzles  134  and  136  may provide a wide angle of coverage while the nozzle  134  has a flow rating of 1 and the nozzle  136  has a flow rating of 2. 
   A blow-off cap  140 ,  142  and  144  is installed on each of the nozzles  134 ,  136 , and  138 , respectively. The blow-off caps  140 - 144  cover the orifice(s) on the nozzles  134 - 138 , each forming a discharge assembly which prevents the nozzles  134 - 138  from clogging with grease and/or other effluent. It should be understood that additional nozzles  134 - 138  and blow-off caps  140 - 144  may be installed to provide protection to other ventilation equipment such as ducts, plenums and filters. 
   One or more detectors  146 ,  148  and  150  may be connected to the control unit  124  by way of one or more wires  152 . The detectors  146 - 150  detect a condition that needs to be suppressed, such as a fire, excess smoke, or heat beyond an acceptable limit, and report the condition to the control unit  124 . Other methods of detection may be used. 
   When the detectors  146 - 150  detect a condition or the manual activation switch  156  is activated, the control unit  124  opens the connection between the bottle  128  and the pipe  130 , such as by energizing the actuator  168 . The fire suppression agent discharges into the pipe  130  at a minimum pressure. The fire suppression agent enters each of the nozzles  134 - 138  and applies a system pressure to each blow-off cap  140 - 144  through the orifice. When the system pressure builds up to a sufficient level, the blow-off cap  140 - 144  is pushed off the nozzle  134 - 138 . The fire suppression agent is discharged out of the orifices of the nozzles  134 - 138 , into the hood  122  and the top end  120  of the chain broiler  100 . By way of example only, the blow-off caps  140 - 144  may be designed to blow off the nozzles  134 - 138  when experiencing system pressure within a range or predetermined limit or limits, such as above a minimum preset pressure. The blow-off caps  140 - 144  stay connected to the respective nozzles  134 - 138  through a lanyard  158 ,  160  and  162 , chain or other device after a fire discharge situation. 
   One or more fire suppression agents may be used. For example, a fixed amount of wet chemical agent from the bottle  128  may be discharged through the nozzles  134 - 138 . Alternatively, following the discharge of a wet chemical agent, water from the water source  129  may be discharged through the nozzles  134 - 138 , such as in a hybrid system. Alternatively, a clean extinguishing agent may be used instead of a wet chemical agent. A clean extinguishing agent, such as a liquefied gas product, is discharged out of the nozzle  134 - 138  as a liquid and then vaporizes. Optionally, a foam based agent may be used. One or more nozzles may be used to supply the fire suppression agent while the remaining nozzles are used to supply water. Optionally, a dry chemical agent may by applied using a first set of nozzles while a second set of nozzles apply water. 
     FIG. 2  illustrates an alternative fire suppression delivery system  250  and an appliance line  252 . The appliance line  252  may be formed of cooking appliances such as a deep fryer  308 , broiler or oven  310  and cook top  312 . The fire suppression delivery system  250  is provided with three tanks, sources or bottles  254 ,  256  and  258  of fire suppression agent. As discussed previously, the same or different fire suppression agents may be used. Each of the bottles  254 ,  256  and  258  is connected to a pipe  260 ,  262  and  264 , respectively. Arrows indicate possible placement and discharge direction for assemblies of nozzles and blow-off caps. Discharge assemblies  266 ,  268 ,  270 ,  272  and  274  are connected to pipe  260  and discharge into exhaust ducts  276 ,  278  and  280 . Discharge assemblies  282 ,  284 ,  286 ,  288  and  290  may be connected to pipe  262  and discharge into hoods  292 ,  294  and  296 . Discharge assemblies  298 ,  300 ,  302 ,  304  and  306  may be connected to pipe  264  and discharge over the appliance line  252  into the hazard zone. The discharge assemblies may be positioned uniformly or non-uniformly from one end of the appliance line  252  to the other. Each discharge assembly in  FIG. 2  includes a nozzle and a blow-off cap. 
     FIG. 3  illustrates a cross-section of a cover  170  for a blow-off cap (such as blow-off cap  140 ,  142 ,  144 ) in accordance with an embodiment of the present invention. The cover  170  is made of metal or other material able to withstand the temperature gradients produced by the chain broiler  100  or appliance line  252 . The cover  170  has a circular wall portion  184 , a closed end portion  186 , a height H 2  and an outer diameter D 2 . A stem  166  extends from the closed end portion  186  and is discussed further below. The circular wall portion  184  and closed end portion  186  have outer and interior cap surfaces  172  and  174 , and form an open-ended cavity  176  for accepting the nozzle  134  ( FIG. 1 ). The cavity  176  has a height H 4 , a first diameter D 3 , a second diameter D 4 , and a closed end  177 . 
   The wall portion  184  has a thickness T 1  at a first end  182  and a thickness T 2  at a second end  183 . The wall portion  184  may have a beveled inner edge  188  along the first end  182 . A receptacle  178  with a depth D 1  and a height H 1  is formed in the cavity  176 , starting at a height H 3  from the interior cap surface  174  of the closed end  177 . The receptacle  178  forms a first angle  180  with the interior cap surface  174  and a second angle  181  with a protrusion  164 . First and second angles  180  and  181  may be approximately 90 degrees. The receptacle  178  may be a groove which retains a retention element, such as an O-ring. The depth D 1  and the height H 1  may vary depending upon the size of the retention element or O-ring, operating pressures of the fire suppression delivery system  101 , and the like. It should be understood that the details illustrated and discussed in  FIG. 3  are optional, and that a cover  170  may be formed having details different from those shown. Additionally, the diameters, height and width relationships may vary and are not limited to the relationships illustrated. Furthermore, the overall shape of the cover may vary. 
     FIG. 4  illustrates a view of the blow-off cap  140  with a retention element installed within the cover  170  in accordance with an embodiment of the present invention. The retention element may constitute an O-ring  190 , which is inserted into the cavity  176  of the cover  170  and securely retained by the receptacle  178 . 
     FIG. 5  illustrates a side view of the nozzle  134  in accordance with an embodiment of the present invention. The nozzle  134  has a discharge end  192  and an inlet end  194 . The inlet end  194  is interconnected with the pipe  130  ( FIG. 1 ) such as with a nut  198 , press fitting, or other connector. Towards the discharge end  192 , the nozzle  134  has a cap receiving portion  200  with an outer nozzle surface  216 . The cap receiving portion  200  is inserted into the cavity  176  of the cover  170 . The nozzle  134  is made of metal and has a channel (not shown) formed within for conveying fire suppression agent received from the pipe  130  at the inlet end  194  to an orifice at the discharge end  192 . 
     FIG. 6  illustrates the discharge end  192  of the nozzle  134  in accordance with an embodiment of the present invention. The discharge end  192  has one or more orifices  196  in communication with the channel. The suppression agent is released through the orifice  196 . 
     FIG. 7  illustrates a side view of the cap receiving portion  200  of the nozzle  134  in accordance with an embodiment of the present invention. The cap receiving portion  200  may be formed of a single piece of material and has a first portion  202 , a receptacle  204 , second and third portions  206  and  210 , and a recess  212 . The first portion  202  has a diameter D 10  and a height H 10 . Referring also to  FIG. 3 , the diameter D 10  is substantially equal to or slightly less than the diameter D 4  of the cavity  176 , and the height H 10  is substantially equal to, or slightly less than, the height H 3 . 
   The receptacle  204  may be formed adjacent the first portion  202  as a groove having a diameter D 11  and a height H 11 . The receptacle  204  is configured to snappingly receive the O-ring  190  ( FIG. 4 ) when the nozzle  134  is inserted into the cavity  176  of the cover  170 . The second portion  206  is formed adjacent the receptacle  204 , and has a diameter D 12  and a height H 12 . The diameter D 12  is substantially equal to or slightly less than the diameter D 4  of the cavity  176  and the diameter D 10  of the first portion  202 . The diameter D 11  of the receptacle  204  is less than each of the diameters D 10  and D 12  by a depth  208 . The depth  208  is determined by at least one of the size, width or thickness of the O-ring  190  and the amount of pressure required to push the blow-off cap  140  off the nozzle  134  during a fire discharge situation. 
   The third portion  210  is formed adjacent the second portion  206  and has a diameter D 13  and a height H 13 . The diameter D 13  is substantially equal to or slightly less than the diameter D 3 . A surface  214  of the third portion  210  is configured to rest against a surface  165  of the protrusion  164 . The recess  212  has a diameter D 14  and a height H 14  which may be varied depending upon the height H 4  of the cavity  176 . Therefore, a total height H 15  of the cap receiving portion  200  is substantially equal to, or slightly greater than, the height H 4 . The recess  212  may be configured to receive an interconnecting member attached to the blow-off cap  140 . As stated previously with  FIG. 3 , the details and dimensions of the cap receiving portion  200  of the nozzle  135  illustrated in  FIG. 7  are exemplary, and thus may vary and are not limited to the relationships shown. 
     FIG. 8  illustrates a cross-section of the blow-off cap  140  having an interconnected lanyard  220  in accordance with an embodiment of the present invention. The lanyard  220  may be formed of a wire  222 , metal mesh, chain, or other material capable of withstanding the extreme heat experienced within the chain broiler  100  and the appliance line  252 . A small loop  236  is formed in a first end  224  of the wire  222  and held by a crimp  226 . The loop  236  is then preened or pressed over the stem  166 . The stem  166  may be formed with a cavity  167  or hole therein. The outer edge of the stem  166  may be rolled outward and down in the direction of arrows  234 , retaining the loop  236  on the stem  166 . Alternatively, a clip (not shown) may be attached to stem  166  and the wire by the crimp  226 . The loop  236  or clip attached to or pressed over the stem  166  may be free to swivel. A second, larger loop  228  is formed in a second end  232  of the wire  222 . The loop  228  interconnects with the nozzle  134 , such as along recess  212 , so that the blow-off cap  140  is retained by the nozzle  134  after the fire suppression delivery system  101  has activated. 
     FIG. 9  illustrates a cross-section of a discharge assembly  240  of the blow-off cap  140  and the nozzle  134  in accordance with an embodiment of the present invention. The O-ring  190  is installed in the receptacle  178  in the cavity  176  of the blow-off cap  140 . The blow-off cap  140  is pushed onto the nozzle  134  in the direction of arrow A, inserting the cap receiving portion  200  of the nozzle  134  into the cavity  176  until the O-ring  190  is snappingly received by the receptacle  204  in the nozzle  134 . Thus, the interior cap surface  174  ( FIG. 3 ) is in close communication with the outer nozzle surface  216  ( FIG. 5 ). The O-ring  190  and receptacles  178  and  204  create a seal within the discharge assembly  240 , preventing grease and effluent from building up inside the blow-off cap  140 , freezing the blow-off cap  140  to the nozzle  134 , and/or clogging the orifice  196  ( FIG. 6 ). 
   A puff test may be conducted to ensure that the blow-off cap  140  is pushed off the nozzle  134  at the appropriate system or discharge pressure, and may be measured in pressure per square inch (psi). Therefore, the receptacles  178  and  204  and retention element or O-ring  190  provide a predetermined amount of retention resistance to retain the blow-off cap  140  on the nozzle  134 . The discharge pressure range may be based on the normal operation of the fire suppression delivery system  101 . For example, the fire suppression delivery system  101  may be set to operate normally between 45 and 65 psi, that is, the pressure range experienced at the nozzle  134  during a fire discharge situation will be between 45 and 65 psi. The discharge assembly  240  may be designed to separate at, by way of example only, 50 psi. Thus, when the system pressure builds up to the sufficient level of 50 psi, the blow-off cap  140  is pushed off the nozzle  134 . 
   The receptacle  204  retains the blow-off cap  140  on the nozzle  134  under the defined system conditions. The discharge pressure needed to push the blow-off cap  140  off the nozzle  134  may be refined by adjusting the size of one or both of the receptacles  178  and  204 . For example, by increasing the depth  208  ( FIG. 7 ) and/or the height H 11  of the receptacle  204 , more pressure is needed to push the blow-off cap  140  off the nozzle  134 . Alternatively, an O-ring  190  or other retention element having a different diameter, thickness or physical properties may be used. 
   In addition, a minimum operating limit or range may be established, ensuring that the discharge assembly  240  withstands a predetermined level of vibration. By way of example only, a vibration test using 0.06 inches of displacement at 10 hertz for 8 hours may be conducted during which it is verified that the blow-off cap  140  stays on the nozzle  134 . The discharge assembly  240  is also designed to withstand hot and cold temperature gradients experienced during cooking operations, such as fluctuations between 70 degrees and 200 degrees. Optionally, a single receptacle may be formed in either the blow-off cap  140  or nozzle  134  to retain the O-ring  190 . The receptacle may be adjusted in height, width, and/or diameter to adjust the retention resistance of the discharge assembly. 
     FIG. 10  illustrates the nozzle  134  and the blow-off cap  140  in accordance with an embodiment of the present invention. The lanyard  220  is connected to the blow-off cap  140 , and the O-ring  190  is installed in the receptacle  178  inside the cavity  176 . The receptacle  204  on the nozzle  134  accepts the O-ring  190 , and retains the blow-off cap  140  in place. When the fire suppression delivery system  101  is activated, the discharge pressure created at the orifice  196  is great enough to overcome the retention resistance and push the blow-off cap  140  off the nozzle  134 . Fire suppression agent is discharged through the orifice  196 . 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.