Patent Application
20190091500
This invention relates generally to a pressure maintenance device having an automatic switch for use in a fire protection sprinkler system, and a method of using a pressure maintenance device in a fire protection sprinkler system.
In fire protection sprinkler systems, dry-pipe sprinkler systems are typically used instead of wet-pipe sprinkler systems when a piping network of the sprinkler system will be exposed to temperatures below 40° F. In a positive pressure-type system, the piping network is charged with pressurized fluid, such as air or nitrogen, instead of water, to prevent damage to the piping network due to freezing water. Dry-pipe systems use a dry-pipe valve that holds the water in a fluid supply and serves as the interface between the pressurized fluid and the fire extinguishing fluid. When a fire occurs and a sufficient amount of heat is generated, one or more sprinklers connected to the piping network operate (i.e., open), causing the pressurized fluid in the piping network to escape through the opened sprinklers, and, therefore, causing the pressure of the pressurized fluid within the piping network to drop. Once the pressurized fluid pressure drops below a predetermined level, the dry-pipe valve opens, allowing water to flow through the piping network to the open sprinklers. Dry-pipe systems require a reliable supply of pressurized fluid to function properly. Due to the delay of water delivery from the dry-pipe valve to the open sprinklers, dry-pipe systems are subject to limitations, such as size restrictions, and may have a need for additional components, such as accelerators or exhausters.
Preaction sprinkler systems employ the same principle as dry-pipe sprinkler systems (i.e., water is not normally contained within the piping network, and instead, the piping network is at least partly filled with a pressurized fluid, such as nitrogen). Preaction sprinkler systems differ from dry-pipe sprinkler systems in that the pressurized fluid in the piping network is not required to be under pressure, a supplemental detection system is installed in the same area as the sprinklers, and a preaction valve is used to control introduction of the fire extinguishing fluid, such as water, into the piping network. Preaction valve operation depends upon one or two of the following events occurring: sprinkler activation and detection device activation.
There are three variations of preaction systems, including a non-interlock system, a single interlock system, and a double interlock preaction system. In a non-interlock system, one of either event mentioned above must occur before the preaction valve opens to admit water to the system. In a single-interlock system, the detection device must be activated in order for the preaction valve to open and admit water to the system. In a double-interlock system, both sprinkler activation and detection device activation must occur before the preaction valve opens and water is introduced into the piping network.
An advantage of preaction systems, and in particular, double-interlock preaction systems, is the dual action required for water release. This feature provides an added level of protection against inadvertent discharge of water. For this reason, preaction systems are frequently employed in water sensitive environments such as archival vaults, fine art storage rooms, rare book libraries, and computer centers.
A pressure maintenance device, also known as an air maintenance device, may be used with a dry-pipe or preaction fire protection sprinkler system to regulate the pressure of the pressurized fluid in the sprinkler system. A pressure maintenance device limits the flow rate of the pressurized fluid into such a system, so that a rate that pressurized fluid is supplied to the piping network is less than a rate at which pressurized fluid will escape from an open sprinkler. A pressure maintenance device also regulates the pressure of the pressurized fluid in the sprinkler system when the sprinklers are closed, ensuring the pressurized fluid in the piping network of the sprinkler system remains pressurized so that the sprinkler system functions as intended. In addition, a pressure maintenance device allows for a manual bypass of the pressure regulator for rapid pressurization, for example, following maintenance or testing.
Both dry-pipe and preaction systems require a reliable source of pressurized fluid, such as air or gas, in order to maintain sufficient pressure within the piping network. To this end, dry-pipe and preaction systems are connected to a fluid supply for supply of the pressurized fluid and a pressure monitoring device. For example, U.S. Pat. No. 5,027,905 (Cousineau et al.) teaches a fire sprinkler control apparatus having a solenoid valve, normally closed to prevent water from the water supply from entering into a conduit leading to fluid flow lines, a sniffer valve, and an air source connected to the sniffer valve. The sniffer valve maintains the pressure of air in the conduit and the fluid flow lines at an air pressure of 60 psi. If the pressure level in the conduit drops below 50 psi, a secondary pressure switch is provided as a precautionary measure, emitting a warning that a slow pressure leak has developed, and indicating maintenance must be performed before water is released into the fluid flow lines. If the pressure level in the conduit drops below 25 psi, a primary pressure switch opens the solenoid, thereby releasing water from the water supply into the fluid flow lines via the conduit.
Dry-pipe and preaction sprinklers systems may use a tank or tanks of liquified or compressed gas as the source of pressurized fluid for the system. When the tank or tanks supplying pressurized fluid to the system are empty or nearly empty, the pressure of the pressurized fluid in the piping network may be reduced and cause the dry-pipe or preaction valve to open admitting water to the piping network without the activation of sprinklers. In the event that ambient temperature in a protected space falls below the freezing point of water (i.e., 32° F.), the water inadvertently introduced to the piping system can freeze, rendering the system inoperative and causing damage to the piping, the sprinklers, and valves.
An object of the invention is to provide a dry-pipe or preaction fire protection sprinkler system in which supply of a pressurized fluid to the sprinkler system is provided by a first pressurized fluid supply and a second pressurized fluid supply, the supply of the pressurized fluid being automatically switched, such that the pressure of the pressurized fluid in the system can be maintained at a predetermined pressure, and unintentional introduction of fire extinguishing fluid into the piping of the sprinkler system can be avoided.
Features of the invention will be described in more detail with reference to the attached drawings.
A fire protection sprinkler system 100, shown in
As shown in
In
In
When the detected temperature is equal to or greater than the predetermined temperature, the fire detection unit 140 sends a signal to the preaction valve 115, and the preaction valve 115 opens, allowing the fire extinguishing fluid to flow through the inlet 120 and the outlet 125 of the preaction valve 115, and the downstream piping 110b. The predetermined temperature T2 is set to a value within the range of 135° F. to 160° F. (57° C. to 74° C.). Alternatively, the fire detection unit 140 may be configured to detect a rate-of-rise of the ambient temperature, i.e., an abnormally fast temperature climb over a short time period. The fire detection unit 140 may alternatively be a spot-type detector (i.e., multiple fire detection units 140 are provided so as to be spaced along a ceiling or high on a wall). The fire detection unit 140 may also comprise a fixed temperature line-type detector, consisting of two cables surrounded by an insulative sheath, designed to breakdown (i.e., to melt) when exposed to heat. The fire detection units 140 may alternatively be smoke detectors, heat detectors, or a combination of heat detectors and smoke detectors.
The upstream piping 110a, the downstream piping 110b, and the pressurized fluid piping 110c may comprise black steel pipe, galvanized steel pipe, stainless steel tubing, or copper tubing, and may have threaded, grooved, or flanged connecting portions that permit attachment of the upstream piping 110a, downstream piping 110b, and pressurized fluid piping 110c to at least the fire extinguishing fluid supply 105, the dry-pipe or preaction valve 115, and the one or more sprinklers 145.
The downstream piping 110b may extend to several sprinklers 145 arranged throughout the occupancy, and connects each sprinkler 145 to the outlet 125 of the main assembly valve, as shown in
When the thermally responsive element 830 operates (i.e., fails) due to an elevated ambient temperature, the plug 825 is released, and the pressurized fluid or fire extinguishing fluid contained in the downstream piping 110b is permitted to flow from the outlet 815 of the sprinkler 845 into the occupancy. For example, when the sprinkler system 100 is in the activated state, fire extinguishing fluid, such as water, is supplied to the downstream piping 110b and to the sprinklers 845. In addition, the sprinkler 845 may include frame arms 835 extending from the body 800 and forming a hub or junction 840 downstream of the outlet 815. A deflector 850 may be mounted on the junction 840, and when the fire extinguishing fluid exits the outlet 815 of the sprinkler 845, droplets of the fire extinguishing fluid are deflected (i.e., redirected) by the deflector 850 in a spray pattern. The sprinkler 845 may be a pendent sprinkler or a horizontal sidewall sprinkler. The number of sprinklers 845 and the arrangement thereof within the occupancy is to be set in accordance with the standards set forth in Chapter 8 of the National Fire Protection Association Standard 13 (“NFPA 13”), published by the National Fire Protection Association, of Quincy, Mass., United States, and/or in Sections 2.1.3, 2.2.3, and 2.3.3 of FM Global Property Loss Prevention Data Sheet 2-0, published by FM Global, of Johnston, R.I., United States.
As shown in
A supply pressurized fluid pressure sensor 230 is connected to at least the first pressurized fluid valve 210 and to the second pressurized fluid valve 225, and is configured to detect the pressure of the pressurized fluid supplied by one of the first pressurized fluid valve 210 and the second pressurized fluid valve 225. When the output of the supply pressurized fluid pressure sensor 230 indicates that the pressure of the pressurized fluid supplied by the first pressurized fluid supply 210 is less than the second pressure setting of the second pressure regulator 220, the pressure maintenance device 260 switches from a primary supply mode, in which the pressurized fluid is supplied by the first pressurized fluid supply 250, to a secondary supply mode, in which the pressurized fluid is supplied by the second pressurized fluid supply 255. Alternatively, in the embodiment shown in
The switch 235 is configured to receive the detected supply pressurized fluid pressure, and when the pressure maintenance device 260 is in a primary supply mode, the switch 230 is configured to permit supply of the pressurized fluid through the first pressurized fluid valve 210, and to prohibit supply of the pressurized fluid through the second pressurized fluid valve 225, such that the pressurized fluid is only supplied to the pressurized fluid piping 110c from the first fluid supply 250. When the pressure maintenance device 260 is in a secondary supply mode, the switch 235 is configured to permit supply of the pressurized fluid through the second pressurized fluid valve 225, and to prohibit supply of the pressurized fluid through the first pressurized fluid valve 210, such that the pressurized fluid is only supplied to the pressurized fluid piping 110c from the second fluid supply 255.
When the outlet pressurized fluid pressure detected by the outlet pressurized fluid pressure sensor 245 is greater than or equal to a first predetermined pressure P1, the supply pressurized fluid pressure detected by the supply pressurized fluid pressure sensor 230 is greater than or equal to a second predetermined pressure P2, and the bypass valve 280 is in the closed position, the pressure maintenance device 260 operates in the primary supply mode while the fire protection sprinkler system 100 is in the non-activated state. That is, the pressurized fluid is supplied from the first pressurized fluid supply 250 through the first pressurized fluid inlet 200, the first pressure regulator 205, the first pressurized fluid valve 210, and the outlet pressure regulator 240 to the pressurized fluid outlet 265. The switch 235 may indicate that the pressure maintenance device 260 is in the primary supply mode. When the outlet pressurized fluid pressure detected by the outlet pressurized fluid pressure sensor 245 is less than the first predetermined pressure P1, the supply pressurized fluid pressure detected by the supply pressurized fluid pressure sensor 230 is less than the second predetermined pressure P2, and the bypass valve 280 is in the closed position, the pressure maintenance device 260 automatically switches from the primary supply mode to the secondary supply mode, while the fire protection sprinkler system 100 is in the non-activated state. That is, the pressurized fluid is supplied from the second pressurized fluid supply 255 through the second pressurized fluid inlet 215, the second pressure regulator 220, the second pressure second pressurized fluid valve 225, and the outlet pressure regulator 240 to the pressurized fluid outlet 265. The switch 235 may indicate that the pressure maintenance device 260 is in the secondary supply mode.
In an embodiment that includes solenoid valves as the first pressurized fluid valve 210 and the second pressurized fluid valve 225, when the supply pressurized fluid pressure detected by the supply pressurized fluid pressure sensor 230 is less than the first predetermined pressure P1, the switch 235 may function to close the first pressurized fluid valve 210 and open the second pressurized fluid valve 225. Upon switching from the primary supply mode to the secondary supply mode, or, in the embodiment having solenoid valves, upon closing of the first pressurized fluid valve 210 and opening of the second pressurized fluid valve 225, the pressurized fluid is permitted flow from the second pressurized fluid supply 255, through the second pressurized fluid inlet 215, the second pressure regulator 220, the second pressurized fluid valve 225, the outlet pressure regulator 240, and the pressurized fluid outlet 265. Alternatively, the switch 235 may only function to open the second pressurized fluid valve 225 without closing the first pressurized fluid valve 210.
When the bypass valve 280 is in the open position, the pressurized fluid is supplied from one of the first pressurized fluid supply 250 via the first pressurized fluid inlet 200, in the embodiments shown in
When the sprinkler system 100 is in the activated state, and the main assembly valve is open, a check valve 135 provided between the pressure maintenance device 160 and the main assembly valve 115 prevents fire extinguishing fluid from passing into the pressurized fluid piping 110c and the pressure maintenance device 160. The check valve 135 serves the purpose of preventing flooding of the pressure maintenance device 160 with the fire extinguishing fluid.
As shown in
If the detected supply pressure is less than the second predetermined pressure P2, the pressure maintenance device 260 supplies the pressurized fluid from the second pressurized fluid supply 255 (i.e., the pressure maintenance device 260 supplies the pressurized fluid in a secondary supply mode) in step S6010. Then, the process returns to step S6000. The second predetermined pressure P2 may be the set pressure of the second pressure regulator 220.
As shown in
If the detected supply pressure is less than the second predetermined pressure P2, the switch 235 of the pressure maintenance device 260 switches at least the second pressurized fluid valve 225 that may be a solenoid valve, in step S7010. Then, in step S7012, the pressure maintenance device 260 supplies the pressurized fluid from the second pressurized fluid supply 255 (i.e., the pressure maintenance device 260 supplies the pressurized fluid in a secondary supply mode). Then, the process returns to step S7000. The second predetermined pressure P2 may be the set pressure of the second pressure regulator 220.
In another embodiment, in addition to opening the second pressurized fluid valve 225, the switch 235 may operate to close the first pressurized fluid valve 210 that may also be a solenoid valve.
In both of the methods shown in
By virtue of the above-described invention, when an inadvertent loss of pressure occurs in a fire protection sprinkler system, due to a leak in the sprinkler system or due to depletion of a first pressurized fluid supply, supply of the pressurized fluid is automatically switched from the first pressurized fluid supply to a second pressurized fluid when the sprinkler system is in the non-activated state.
Although this invention has been described in certain specific exemplary embodiments, many additional modifications and variations would be apparent to those skilled in the art in light of this disclosure. It is, therefore, to be understood that this invention may be practiced otherwise than as specifically described. Thus, the exemplary embodiments of the invention should be considered in all respects to be illustrative and not restrictive, and the scope of the invention to be determined by any claims supportable by this application and the equivalents thereof, rather than by the foregoing description.
This non-provisional application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/563,581, filed on Sep. 26, 2017, and the disclosure thereof is incorporated into this application by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62563581 | Sep 2017 | US |
