Fluid handling – Diverse fluid containing pressure systems – Fluid separating traps or vents
Patent
1993-10-19
1996-03-26
Schwadron, Martin P.
Fluid handling
Diverse fluid containing pressure systems
Fluid separating traps or vents
137177, 96204, B67D 558
Patent
active
055012469
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a device for the separation of gas which may be entrained in a flow of liquid. Preferably, the device also controls the amount of gas that is expelled in the liquid that is dispensed from the device.
BACKGROUND OF THE INVENTION
In many applications it is important to measure accurately the volume of liquid passing through a pipe or tube, for example a fuel dispenser, such as a petrol pump. If the liquid is contaminated with gas, such as air, vapour and/or other gas, the meter, which cannot differentiate between the liquid and the gas, will produce an erroneous reading for the volume of liquid dispensed. Thus the purchaser of the fuel will pay not only for the fuel actually dispensed, but also for any gas entrained in the fuel flow line.
It is known, for example from Australian Patent No. 460441, to provide a device in the fuel flow line to separate the gas from the liquid by arranging for the liquid to flow through a separation tank, located upstream of the meter, in which any gas can rise to the top and from which liquid is drawn from the bottom. Exit of liquid out of the tank is via a main valve which is controlled either by a pilot valve or by an orifice to close the main valve when there is a substantial volume of gas in the tank. This gas escapes from the tank via a vent passage to an air separation sump, the tank replacing the escaping gas with further liquid or liquid/gas mixture. When the pilot valve or orifice sense that the liquid/gas mixture in the tank has again reached a certain level, the main valve is opened to allow liquid to flow at normal operating levels.
Although the above-described device works reasonably well, it needs to be built into the liquid dispensing system with the various valves and the orifice being interconnected by pipes or hoses which requires a substantial investment and a relatively large amount of space.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a device for separating gas from liquid, which is more compact, has a small number of components, is cheap to manufacture and which will automatically adapt to the requirements of liquids of different viscosities, densities and/or flowrates.
Accordingly, the invention provides a device for separating gas entrained in a flow of liquid, the device comprising a main housing having a liquid inlet and a liquid outlet, a separation volume within the housing between the inlet and the outlet, a vent passage extending from the separation volume to the outside of the housing, a main valve within the housing for controlling flow of liquid between the inlet and the outlet, means for detecting the presence of gas in the vent passage, a pilot valve coupled to the detecting means and the main valve for controlling the main valve in dependence on the presence of gas in the vent passage.
In a preferred embodiment, the detecting means is a dual orifice arrangement in the vent passage and the pilot valve is coupled to the dual orifice arrangement via a first control passage within the housing. The dual orifice arrangement is preferably removable from the vent passage.
In a preferred embodiment of the invention, the pilot valve is a poppet valve operated by a diaphragm which is caused to close when gas is detected in the vent passage. The pilot valve is preferably arranged to close a second control passage extending between the main valve, which is preferably a diaphragm valve, and an inlet downstream of the main valve. The second control passage is preferably coupled to the main valve on the downstream side such that, when the second control passage is open, pressure on the downstream side of the diaphragm is smaller than on the upstream side, thereby causing the diaphragm to be opened against the action of a biasing means, such as a spring. When, however, the second control passage is closed by the pilot valve, the pressure on the downstream and upstream sides of the diaphragm is equalised by means of a bleed connection between the two sides of t
REFERENCES:
patent: 2680538 (1954-06-01), Fishburn
patent: 2960104 (1960-11-01), Hudson
patent: 3867955 (1975-02-01), Scott et al.
patent: 4978374 (1980-12-01), Janssen et al.
Burns David R.
Turner Victor C.
Gilbarco Limited
Lee Kevin L.
Schwadron Martin P.
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