Gas separation – With means securing or retaining separating media – Unit or cohesive sheet-like media in flow line or frame
Reexamination Certificate
2000-08-28
2002-10-08
Smith, Duane S. (Department: 1724)
Gas separation
With means securing or retaining separating media
Unit or cohesive sheet-like media in flow line or frame
C055S502000, C055S503000, C055S504000
Reexamination Certificate
active
06461397
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a filter assembly for collecting material that is entrained in a gas stream such as particulate solid material or liquid in an aerosol form, and to a tubular filter element for location in a housing to collect such material.
2. Present State of the Art
Filtration of gas in a compressed gas system is generally required so that the gas is sufficiently clean for a subsequent application or to minimise adverse effects of impurities on components of the system. For example removal of compressor oil can be required to minimise chemical contamination and accumulation on valves which might lead to malfunction of the valves, and removal of particulate solid material can be required to minimise abrasion.
A known filter assembly for use in compressed gas systems is sold by Domnick Hunter Limited under the trade mark OIL-X. It comprises a housing having inlet and outlet ports for the gas stream that is to be filtered and a tubular filter element which can be located in the housing and is configured for the gas stream to flow through its wall, for example generally outwardly from the inside of the filter element to the outside. When the assembly is used to collect liquid in the gas stream (for example which is carried in the stream as aerosol droplets), the filter element will cause the liquid to coalesce. Coalesced liquid then drains from the filter element and collects in the housing for discharge. For such applications, the housing will include an outlet for discharge of any collected liquid.
The housing of such a filter assembly comprises a body section in which the filter element is located and in which a reservoir for any collected liquid can be provided, and a head end cap with the inlet and outlet ports for the gas stream. The end cap includes appropriate conduits within it for the gas stream to flow between the ports and the filter element. The end cap is formed in one piece by a casting process. Seals are formed at the ends of the or each such conduit between (a) the conduit and the filter element and (b) the conduit and a component of the compressed gas system to or from which the gas stream in the filter assembly flows.
The incorporation of a flow conduit into the housing of a filter assembly of this kind places restrictions on the configuration of the flow conduit.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a filter assembly which includes a flow conduit which can be fitted into the housing for controlling flow of gas between a port in the housing and the filter element.
Accordingly, in one aspect, the invention provides a filter assembly for collecting material that is entrained in a gas stream, which comprises a housing for a tubular filter element arranged for the gas stream to flow through its wall, the housing having inlet and outlet ports for the gas that is to be filtered, the assembly further comprising a flow conduit which has a first conduit opening for communication with one of the ports for the gas that is to be filtered and a second conduit opening for communication with the filter element, the housing and the flow conduit being arranged so that the formation of a seal between the first conduit opening and the said port involves sliding the flow conduit generally transversely relative to the direction of flow of fluid through the port.
The assembly of the invention has the advantage that the flow conduit can be made with a configuration that is not restricted by having to be formed as an integral part of the housing. This arises because the flow conduit is defined by a component which is separable from the housing head and which can be formed separately from the head. For example, when the axes of the first and second conduit openings are not aligned, the flow path between the openings can be configured to present a continuous smooth flow path to the gas stream flowing along it between the first and second conduit openings, generally between the port in the housing and the tubular cavity within the filter element. The smooth flow path can be constructed to reduce restriction of the flow of the gas stream compared for example with a flow conduit which presents a discontinuous flow path which is sharply angled or contains steps of other obstructions. Frequently, the angle between the axes of the conduit openings might be at least about 30°, especially at least about 60°, and generally the axis of the first conduit opening will be substantially perpendicular to the axis of the second conduit opening. The flow conduit can be constructed for such applications with a smoothly curved transition between the conduit openings to minimise restrictions to the flow of the gas stream.
Generally, the housing will comprise an end cap and a body section in which the filter element is located when the assembly is in use. One or more ports for gas to be filtered can then be provided in the end cap; the end cap can then accommodate the flow conduit within it when the assembly is in use to provide a flow path for gas to be filtered between one of the ports and the filter element located in the housing body section. A filter assembly which comprises a housing having a body section and an end cap, with a flow conduit received in the end cap, is disclosed in copending U.S. application Ser. No. 09/581,321 entitled Filter Assembly. Subject matter disclosed in that application is incorporated in the specification of the present application by this reference.
The flow conduit can be made with additional features during its manufacture. For example, a port might be formed in it for connection to means for indicating the pressure within the conduit. A tang might be formed on the flow conduit which can be received in a recess in the housing when the flow conduit is properly located within the housing. This can provide an indication that the flow conduit is properly located, for example by visual inspection or as a result of the tang being resiliently deformable and being received in the recess with a snap fit which can be detected visually or by feel by the operator. For example, when located in the recess, the tang might prevent withdrawal of the flow conduit from within the housing.
The present invention therefore enables the operating efficiency of a filter assembly to be improved because of the greater design freedom that is available in the design of the flow conduit compared with a flow conduit that is formed integrally in the housing. Furthermore, the design freedom enables additional features to be incorporated into the design of the flow conduit conveniently. These advantages are significant in terms of design and operation of the assembly of the invention. It has been found that it is entirely feasible to produce the assembly of the invention with satisfactory seals between the flow conduit and the housing and filter element as necessary, so that the assembly of the invention can function without loss of gas from the stream being filtered. Such seals can be in the form of for example compressible gaskets. They might be provided by elastomeric O-rings which can be located in machined grooves in the components.
Generally, the flow of the gas stream towards and away from the assembly will be generally horizontal. The tubular filter element will generally be arranged vertically so that the housing port is at the top of the housing with the filter element located depending below it. When the housing comprises an end cap and a body section, the end cap will be located at the top of the housing when in use, with the body section below it. In such constructions, the axis of the first conduit opening and the axis of the second conduit opening will not be aligned. Generally, the axis of the first conduit opening will be substantially perpendicular to the axis of the second conduit opening.
Assembly of the flow conduit within the housing involved sliding the flow conduit generally transversely relative to the direction of flow of fluid through the port. The flow conduit will generally be slid alon
Domnick Hunter Limited
Smith Duane S.
Workman & Nydegger & Seeley
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