Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-05-08
2001-12-25
Trieu, Van (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S611000, C073S251000
Reexamination Certificate
active
06333695
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the fields of flow detection, measurement and control. The invention also relates to fire suppression systems. In particular, the invention relates to multi-purpose piping systems for fire protection in structures and flow elements related thereto. The invention relates to systems for ensuring adequate circulation to fire protection sprinklers to minimize stagnation and/or freezing.
2. Description of the Prior Art
Practically any system where fluid flows in a conduit can use flow measurement devices. There are any many different kinds of flow measurement devices as there are systems where fluids flow in a conduit (such as a typical pipe). For example, it is well known that there is a pressure drop across an orifice plate, and that this pressure drop can be used to determine the fluid flow through the pipe. The pressure drop is proportional to the velocity of the fluid in the pipe. As another example, a positive displacement device may be placed in a conduit, which directly measures the volume of fluid flowing therethrough. From the known volume measured by the positive displacement device, the velocity of the fluid in the pipe can be determined. An example of this type device is a paddle flow switch commonly used in fire protection systems. Each type of flow measurement device has its strengths and weaknesses, and may be applicable to one system, while not being suitable for another.
Check valves (single and double acting) are also widely used in systems where fluids flow in conduits. The purpose of a check valve is to allow flow in one desired direction, but prevent flow in the opposite undesired direction. Existing check valves often use a moving seat, which is forced open by fluid flowing in the desired direction, but which moving seat is sealingly forced against an annular shoulder, preventing flow in the undesired, opposite direction.
It is well known to use electronic sensor means to transmit a signal generated by a flow measurement device to a read out or alarm means. The electronic output may be generated in response to a pressure transducer or the like. There are a myriad of ways to generate an electronic signal proportional to flow of a fluid in a conduit. As with our orifice plate noted above, the differential pressure is proportional to the flow in the conduit. Therefore, a differential pressure transducer exposed to the up stream and down stream fluids would produce an output electrical signal proportional to the flow of fluid through the conduit. In the paddle flow switch, the volume between the paddles is known, and a signal is generated indicating the number of revolutions per unit time of the paddle, thus allowing calculation of the flow velocity. Vane-type paddle flow switches are typically used in the fire protection industry.
It is also well known to provide a bypass means for allowing fluid flow around a restriction, in certain circumstances. For example, for use in a multi-purpose piping system, it made be desirable to divert flow around a water softener where the demand for water in the residence for fire protection is greater than is able to flow through the water softener. As another example, in a chemical process, chemicals may be passed through a reactor unit. However, should the reactor become plugged or otherwise unduly restrict the flow, it may be desirable to bypass the reactor so as to prevent damage to the reactor vessel and/or a process upset. In these circumstances, it is necessary to have a bypass means which can divert flow around the flow element causing the pressure drop in certain circumstances.
In most fluid flow systems, each of the above noted flow elements (flow measurement, check valve, bypass means) is a separate fitting which must be placed in the fluid system. It is often desirable to combine as many of the above noted functions into one device as possible. The combination of multiple devices, for example the flow meter, check valve, and means for converting a fluid flow to an electronic out put signal, are obvious. A reduced number of devices reduces complexity, cost, and difficulty of installation of a fluid flow system.
It is also well known to provide a means for enunciating an alarm when water flows through a fire protection system. Typical commercial fire protection systems do not have significant water flow therethrough unless a sprinkler head is activated by a fire. Thus, the typical commercial system need only to detect whether or not flow is present, and if so, an alarm must be enunciated.
In application Ser. Number 09/098,976 filed on Jun. 1, 1998, for an Apparatus And Method For Multi-purpose Residential Water Flow Fire Alarm, a method was disclosed which allows the same piping to be used for both domestic and fire protection needs. The method provided for a flow detection and measurement means which is capable of distinguishing typical domestic flow from fire protection flow caused by the operation of one or more sprinkler heads.
The National Fire Protection Association (“NFPA” ) has established standards for the design and operation of multi-purpose residential fire sprinkler systems. The standard is known as NFPA 13D, 1999 Ed. It defines a multi-purpose piping system (“MPS” ) “piping system within dwellings and manufactured homes intended to serve both domestic and fire protection needs.”
Typical commercial fire sprinkler systems utilize a water flow detector to provide an alarm means. When a flow of sufficient, minimal, volume is detected, typical commercial systems indicate an alarm condition. The only reason that water typically flows in commercial systems is activation of a sprinkler head. Therefore, in a typical commercial system an alarm means need only determine whether or not water is flowing. Paddle flow switches are commonly used to determine when flow occurs in commercial systems. As noted above, these are typically vane-type paddle flow switches.
In the MPS water regularly flows through the common piping. Flows occur to supply domestic needs within the residence. Whenever a sink, shower or toilet valve open, water flows in the MPS. Therefore, the alarm system used on typical commercial applications will not work for the MPS because simply taking a shower might cause a typical commercial flow detector to alarm when used with the MPS.
In light of this problem, typical residential applications have two completely different piping systems: (1) a fire sprinkler piping system, and (2) a domestic piping system. This basically doubles the number of pipes and the amount of plumbing work which has to be performed in a typical residential application. The same set of piping could not previously be used for both systems because the flow alarm could send false signals when domestic water was turned on. Alternatively, a residential application could use a fire detection system (i.e., smoke detector system). However, a smoke detection system does not alarm when water flows. Therefore, with a smoke detection system and no flow alarm, the fire sprinklers could run for days, causing extensive water damage, while the home owner is away on vacation and no alarm would sound. Also, smoke detection systems are expensive.
As noted above, U.S. patent application Ser. No. 09/098,976 filed Jun. 1, 1998, disclosed an Apparatus And Method For Multi-Purpose Residential Water Flow Fire Alarm. The apparatus for use as a multi-purpose residential fire suppression water flow alarm system disclosed in that application was comprised of a supply side for delivering water under pressure; a multi-purpose piping system having a system side with common piping for delivering water from the supply side to a fire suppression side with one or more sprinkler heads and a domestic side for one or more domestic uses; a detecting means for detecting fire protection flow and for distinguishing that flow from a maximum domestic flow, the detecting means being disposed between the supply side and the system side; a drain test connection; and an alarm means. The method of utili
Trieu Van
White Edward L.
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