Automatic temperature and humidity regulation – Air-relief valves – Radiator type
Reexamination Certificate
2000-05-18
2001-11-13
Michalsky, Gerald A. (Department: 3753)
Automatic temperature and humidity regulation
Air-relief valves
Radiator type
C137S200000, C137S202000
Reexamination Certificate
active
06315212
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a device that automatically vents gas, for example air, from a liquid filled system, for example water.
Temperature change liberates gas present in solution which is precipitated in closed systems such as radiators causing reduced system efficiency. Gas venting devices are used in industrial and domestic applications as a means to expel gas products from liquid-filled systems so as to maintain the system efficiency. The most common example is an air vent valve on top of a domestic hot water radiator which is manually operated periodically by a key to release air that has entered the system.
Automatic vents are available and tend to fall into two categories (or a combination thereof). The first type currently commercially available is a float on a lever type vent which utilises raising water levels in the system to elevate a float which exerts force via a lever on a valve to close the air way. The weight of the float and lever cause the valve to open when the water level drops so allowing expulsion of unwanted air. This type is reliable, but large, due to the necessary weight of the float to open the airway against a pressure difference between system pressure inside the radiator and that of atmospheric pressure outside. This makes it aesthetically unacceptable, eliminating it as a viable option for fitting to most domestic radiators and is traditionally fitted as a single unit to a system high-point, which does not then vent air already collected in radiators.
The second type is a hygroscopic vent which is small but liable to leak water. Its operating principle utilises a series of fibre washers that allows the passage of air when they are dry but expand when contacted by water thus closing an exit port. This has been considered unreliable and British Standard BS 5449 does not recommend this type as it may permit water to escape for the first few seconds until the fibre washers expand.
The object of this invention is to provide an improved and more reliable automatic vent that is small, doesn't leak water, and may therefore be more acceptable for domestic and other applications that require miniaturisation of the vent.
SUMMARY OF THE INVENTION
According to the invention there is provided an automatic venting device for venting gas from a system containing liquid, comprising a body defining a connector for connecting to the system, a vent, a member defining an orifice and a valve seat on the member, the body defining a vent path from the connector through the orifice in the valve seat to the vent; a float valve movable between a closed position in which it engages the valve seat to close the vent path, and an open position in which it is spaced away from the valve seat to open the path, wherein the float valve sinks towards the open position in the absence of liquid in the system but is floated towards the closed position when liquid in the system reaches a predetermined level; and a subsidiary valve movable between an open position leaving the vent path open and a closed position in which the vent path is closed, wherein movement of the subsidiary valve to its closed position and back to its open position acts to move the float valve away from its closed position towards the open position.
Prior art vents using float valves have used the float valve alone as a single venting valve. Such prior art float valves have been too large for domestic use, and could not be shrunk. That is because radiator heating systems are pressurised in use and the pressure keeps the float valve in its raised position preventing venting even when the presence of air in the system causes the water level to drop.
In the apparatus according to the invention, on the other hand, the subsidiary valve causes the float valve to move away from its closed position to unseal it. The float valve is then no longer held in its closed position by air pressure and so venting can proceed if required.
The subsidiary valve may be a thermostatic valve which moves to its open position below a predetermined temperature and to its closed position above the predetermined temperature to close the flow path and engage the float valve to move it away from the float valve's closed position. The predetermined temperature may be in the range 30-80° C., preferably 30-50° C.
Alternatively, the apparatus may further comprise hygroscopic material that expands when in contact with liquid to move the subsidiary valve to its closed position, and contracts when the liquid level falls to allow the subsidiary valve to move to its open position. This allows the subsidiary valve to be controlled by water level.
A guide may be provided to locate the float valve constraining it to move between open and closed positions; the guide may comprise guide rails or it may be constituted by the inside face of a hollow body such as a hollow cylinder.
REFERENCES:
patent: 703886 (1902-07-01), Allen
patent: 3088482 (1963-05-01), Ostrem
Bonello Charles
Heffernan John Francis Steeple
Michalsky Gerald A.
Sheridan & Ross P.C.
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