Patent Application
20110108123
The present invention is directed to a method and apparatus for venting air from a fluid system and, in particular, to a method and apparatus for venting air from a fire suppression wet pipe system.
Fire suppression wet pipe systems, such as water-based fire-sprinkling systems, fire suppression stand pipe systems, and the like, when placed in service and when occasionally drained in order to perform maintenance or changes on the system will have air in the piping network. When the piping network of the system is refilled with water, air becomes trapped in the system. This trapped air can cause internal corrosion of the piping network, especially when mild steel or galvanized piping is being used. Oxygen corrosion may be the predominant form of corrosion and metal loss within the fire protection system. Oxygen may enter the fire sprinkler system piping from two sources. First, oxygen may be dissolved in the incoming fresh water that is used to fill the fire sprinkler piping. Second, oxygen is present in any air that is trapped in the fire sprinkler system. Corrosion of mild steel fire sprinkler piping can, therefore, be most active when fresh oxygenated water and air are introduced into the piping during any drain and fill cycle. Draining and refilling the system allows additional corrosion. Each time the system is drained of the fluids and refilled, the high rate of oxygen corrosion that exists with a fresh supply of air will cause additional metal lost from the pipe walls.
To reduce the amount of internal corrosion within the piping network, the fire suppression wet pipe system is vented when it is filled or refilled. While this is commonly performed manually, an air vent valve may be connected at an upper portion of the system to automatically vent the air that rises to that portion of the system. Such air vent valves are configured to close after the air has been removed from the system to prevent any appreciable amount of fluid from being discharged. However, should the air vent valve fail, it may result in extensive discharge of fluid, which could cause water damage to the structure and any goods stored or displayed in the structure, such as a warehouse or retail space, especially if not discovered immediately. Indeed, for systems that operate at a high pressure, such as fire-sprinkling systems, a failed air vent valve may be capable of discharging a very large amount of fluid in a very short amount of time.
A fire suppression wet pipe system air vent assembly that provides a method of automatically venting air from a fire suppression system wet piping network, according to an aspect of the invention, includes providing a primary air vent valve having an inlet and an outlet. The primary air vent inlet is adapted to be connected with the wet pipe system and is configured to vent air, but not water from its outlet. A secondary air vent valve having an inlet and an outlet is provided. The secondary air vent valve is configured to vent air, but not water from its outlet. A fluid conduit connects the primary air vent valve outlet with the secondary air vent valve inlet. The secondary air vent valve provides failsafe air venting upon failure of the primary air vent valve. This provides redundancy to the primary air vent valve while functioning in generally the same manner as the primary air vent valve alone.
The fluid conduit may include a vertically elongated chamber. The secondary air vent valve inlet may be connected above a bottom portion of the chamber, thereby defining a fluid collection space. This allows small amounts of fluid discharged from the primary air vent valve to be accumulated without entering the secondary air vent valve. Such small amounts of fluid should be evaporated by exposure to atmosphere through the secondary air vent valve. The vertically elongated chamber may be in the form of an enclosed chamber.
A fluid responsive valve may be connected with the secondary air vent valve outlet. The fluid responsive valve is normally open and closes in response to fluid at the outlet of the secondary air vent valve. The fluid responsive valve may be a reusable valve.
A fire protection wet pipe system air vent assembly and method of venting air from a fluid system, according to another aspect of the invention, includes providing a primary air vent valve having an inlet and an outlet. The primary air vent inlet is adapted to be connected with a fire protection wet pipe system and is configured to vent air, but not water from its outlet. A secondary air vent valve having an inlet and an outlet is provided. The secondary air vent valve is configured to vent air, but not water from its outlet. A fluid conduit connects the primary air vent valve outlet with the secondary air vent valve inlet. A fluid indicator is provided that indicates the presence of fluid in the conduit. The secondary air vent valve provides failsafe air venting upon failure of the primary air vent valve. The fluid indicator indicates failure of the primary air vent valve. In particular, the presence of an appreciable amount of fluid in the conduit is an indication of likely failure of the primary air vent valve.
The fluid indicator may be, in the form of a visual indicator. The visual indicator may be visible from below the fluid conduit. The visual indicator may be in the form of a sight glass at a bottom portion of the conduit and an indicator element in the conduit that floats away from the sight glass in the presence of fluid in the conduit.
The conduit may include a vertically elongated chamber. The fluid indicator may be in the form of a float switch in the chamber. The fluid indicator may be in the form of both a visual indicator and a float switch in the chamber.
A fluid responsive valve may be connected with the secondary air vent valve outlet. The fluid responsive valve is normally open and closes in response to fluid at the outlet of the secondary air vent valve. The fluid responsive valve may be a reusable valve.
These and other objects, advantages, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.
Referring now to the drawings and the illustrative embodiments depicted therein, a fire suppression wet pipe system air vent assembly 10 includes a primary air vent valve 12 and a secondary air vent valve 18 interconnected by a fluid conduit 24 (
Secondary air vent valve 18 has an inlet 20 and an outlet 22. Secondary air vent valve 18 is also configured to vent air, but not water present at its inlet from passing to its outlet. Fluid conduit 24 connects primary air vent valve outlet 16 with secondary air vent valve inlet 20. In the illustrative embodiment, primary and secondary air vent valves 12, 18 are commercially available. While they are illustrated as being identical, they could be of a different configuration. In the illustrative embodiment, valves 12, 18 are supplied by APCO Willamette Corporation.
In the illustrative embodiment, fluid conduit 24 is made up of a vertically elongated chamber 26 that is connected at an upper portion thereof with outlet 16 through a coupling 36. The secondary air vent valve inlet is connected to chamber 26 at a tap 28 that is above the bottom portion of chamber 26 thereby defining a fluid collection space 30. In the illustrated embodiment, chamber 26 is an enclosed chamber. Secondary air vent valve outlet 22 is covered with a cap screen 38 to allow air, and the like, to escape from outlet 22 while resisting insects, and the like, from entering into the valve.
Fire suppression wet pipe system air vent assembly 10 may further include a fluid indicator that indicates the presence of fluid in chamber 26. In the embodiment illustrated in
Operation of fire suppression wet pipe system air vent assembly 10 can best be understood by reference to
As illustrated in
Thus, the absence of indicator element 46 viewed through sight glass 44 is an indication that primary air vent valve 12 is likely malfunctioning. Assembly 10 can be repaired by the closing of cutoff valve 32, the removal of assembly 10 from fire suppression wet pipe system 52 and the replacement of primary air vent valve 12. Unlike other systems, there are no additional components in the assembly, such as a single action liquid sensitive switch, or the like, that must be replaced at the same time as the primary air vent valve. Moreover, because chamber 26 is sealed, casual water around the job sight will not affect operation of assembly 12, as can occur with other air vent assemblies that employ liquid sensitive switches in an open container. In the illustrated embodiment, visual indicator 42 can be observed from a distance of up to approximately 30 feet or more.
Secondary air vent valve 18 allows airflow from chamber 26 during normal operation of assembly 10. This venting of chamber 26 allows any fluid that casually enters chamber 26 to evaporate over time through valve 18. This is useful because primary air vent valve 12 may discharge small amounts of fluid during the interval that air has escaped the system, but before orifice 56 is fully closed. Over time, such small amount of fluid will evaporate through orifice 60. Also, the location of tap 28 above the bottom of chamber 26 creates collection space 30 for any small amount of fluid entering chamber 26 to prevent the fluid from entering secondary air vent valve 18. In the illustrated embodiment, collection space 30 is approximately 2 to 3 inches in height. The presence of collection space 30 is particularly useful for fire suppression wet pipe systems, which must be placed back into operation daily even for maintenance that may expand several days. In such circumstances, system 52 must be repeatedly drained and refilled daily, thus allowing more fluid to enter chamber 26 without entering secondary air vent valve 18 and allowing the fluid to eventually evaporate. Also, the ability to pass air through both primary and secondary air vent valves 12, 18 allows air to enter fluid system 52 as it is being drained. This helps to drain the system by preventing formation of a vacuum in the system.
Thus, it is seen that fire suppression wet pipe system air vent assembly 10 provides redundancy to the primary air vent valve in a manner that not only avoids damage to surrounding structure and inventory from fluid damage, but also provides a ready indicator to a technician on the ground that the assembly is working properly or has failed. Moreover, in the event of a failure, only the failed component needs to be replaced, thus minimizing maintenance expense. Also, in contrast to known fire suppression wet pipe system air vent assemblies, assembly 10 does not need to be wired, at the cost of several hundred dollars or more, into the fire protection alarm panel or other monitoring panels to indicate a failure of the primary air vent valve. Also, in contrast to known fire suppression wet pipe system air vent assemblies, assembly 10 does not need to be accessed and viewed down into the open pan to visually confirm the operational condition of the unit. Viewing from above the unit is difficult in most installations since the assembly is typically 15 to 35 feet above the floor.
In an alternative embodiment, a fire suppression wet pipe system air vent assembly 110 includes a primary air vent valve 112 and a secondary air vent valve 114 that may be the same as valves 12, 18 in the previous embodiment (
Fire suppression wet pipe system air vent assembly 110 may further include a fluid responsive valve 80 connected with outlet 122 of secondary air vent valve 114. Fluid responsive valve 80 is normally open, but is self-closing in the presence of fluid, such as water, at outlet 122 of secondary air vent valve 114. The purpose of valve 80 is to provide even further failsafe operation to the air vent assembly. In the unlikely event that both primary air vent valve 112 and secondary air vent valve 114 fail in an open state, the presence of water at outlet 122 will cause fluid responsive valve 80 to close, thus providing further failsafe capabilities to air vent assembly 110. Fluid responsive valve 80 may be, for example, a motor-operated ball valve that is operated electrically or pneumatically, or the like. Such a valve is commercially available from various sources, such as Automated Valve Corporation of Novi, Mich. While it is preferred that valve 80 be reusable so that it does not need to be replaced in the event of its operation, non-reusable valves, such as the WAG disclosed in U.S. Pat. No. 6,926,023, may be used.
In the illustrated embodiments, the various components making up fluid system air vent assemblies 10, 110 are made from ferrous and/or cuprous metals, such as cast iron, brass, and stainless steel, for fire suppression wet pipe systems due to the high fluid pressures of such systems. They may be made from other materials for lower pressure applications. In the illustrated embodiments, the various pipe joints are sealed with a Loctite thread sealant which has been found to be less likely to break off and potentially clog an orifice than other joint seal compounds.
Various changes are intended to be comprehended by the various embodiments of the invention. For example, although illustrated with bottom entry air vent valves, assembly 10, 110 could be implemented with side entry valves. Such valves may further reduce the overall height of assembly 10, 110 by one or more inches. This may be useful because assembly 10, 110 is positioned at the highest point in the fluid system, which may have restricted overhead space. The reduction in the overall height of assembly 10, 110 may allow it to fit within such restricted space.
Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.
