Gas separation – With means securing or retaining separating media – Unit or cohesive sheet-like media in flow line or frame
Reexamination Certificate
2002-03-04
2003-12-16
Smith, Duane (Department: 1724)
Gas separation
With means securing or retaining separating media
Unit or cohesive sheet-like media in flow line or frame
C055S317000, C055S322000, C055S327000, C055S490000, C055S509000, C055S513000, C055S498000, C055S502000, C055S508000
Reexamination Certificate
active
06663685
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The 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. The Relevant Technology
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 an aerosol), 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 filter element comprises a filter medium and first and second end fittings by which the filter medium is supported within the housing. The end fitting at the end of the filter element remote from the head end cap is connected to the end cap by means of a tie rod which extends through the tubular cavity within the filter element and engages the end cap by means of a thread. The extension of the tie rod through the filter element and at least partially through the end cap can disturb the flow of the gas stream through filter assembly giving rise to increased flow resistance. This therefore reduces the operating efficiency of the assembly.
SUMMARY OF THE INVENTION
The present invention provides a filter assembly in which a support extends between the filter element at or towards its end and the internal side wall of the housing at a location above the end of the housing remote from the head end cap.
Accordingly, in one aspect, the invention provides a filter assembly for collecting material that is entrained in a gas stream, which comprises:
(a) a housing for a filter element, which has first and second ends with an inlet and an outlet at the first end for the gas that is to be filtered, and a support surface on its internal wall at a point towards its second end, the first and second ends of the assembly defining an assembly axis which extends between the said ends,
(b) a tubular filter element arranged within the housing for the gas stream to flow through its wall between the inlet and the outlet, and
(c) a support for locating the filter element within the housing, comprising a plurality of fingers which extend between the filter element at or towards its end and the support surface on the internal side wall of the housing, each of the fingers being resiliently flexible so that they can be deformed resiliently when force is applied to the filter element in the direction towards the second end of the assembly.
In another aspect, the invention provides a filter assembly for collecting material that is entrained in a gas stream, which comprises:
(a) a housing for a filter element, which has first and second ends with an inlet and an outlet at the first end for the gas that is to be filtered, and a support surface on its internal wall at a point towards its second end, the first and second ends of the assembly defining an assembly axis which extends between the said ends,
(b) a tubular filter element arranged within the housing for the gas stream to flow through its wall between the inlet and the outlet, and
(c) a support for locating the filter element within the housing, comprising a plurality of fingers which extend between the filter element at or towards its end and the support surface on the internal side wall of the housing, each of the fingers being inclined to the assembly axis.
The housing has inlet and outlet ports for the gas stream. It can comprise a head end cap and a body section, at least one of the ports for the gas stream being provided in the head end cap. The assembly of the invention has the advantage that flow of gas through the housing head end cap and the internal cavity within the filter element (for example from the inlet to the housing for flow through the filter medium in an outward direction if the assembly operates in an in-to-out mode) is not restricted by a tie rod extending between the bottom end fitting on the filter element into the end cap. It has been found that support for the distal end of the filter element against force applied to it by pressurised gas supplied to the housing head end cap can be provided satisfactorily by a support extending to the side wall of the housing body section, the body section being connected to the end cap. The support can locate the filter element within the housing against force generally along the axis of the filter element, resulting from a pressure differential across the element.
Furthermore, the effectiveness of the seal between the filter element and the housing head end cap is not dependent on the installer of the filter element properly engaging a tie rod in the housing head end cap. By accurate control of the dimensions of the filter element and the components of the housing, the seal can be arranged to be formed reliably when the body section and the head end cap of the housing (with the filter element located inside) are connected to one another.
The present invention therefore enables the operating efficiency of a filter assembly, and the security of the seals in the assembly, to be improved compared with an assembly which uses a tie rod.
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 end cap is arranged at the top of the housing, with the body section depending below it. The support for the filter element will then be located at the lower end of the element.
The filter element will generally comprise a filter medium and first and second end fittings. The support can conveniently provided on one of the end fittings. In particular, it can be preferred for the support and the end fitting to be provided as a single component, possibly as a result of being formed together for example as a single piece moulding, or as a result of being connected to one another for example mechanically, or by bonding (with or without an adhesive material). When the support is provided on one of the end fittings, it will be the bottom end fitting.
Preferably, the fingers of the support are inclined to the axis of the housing, in a direction away from the housing head end cap. For example the angle between the fingers and the said axis can be at least about 45°, preferably at least about 60°, more preferably at least about 75°.
Preferably, the support surface faces axially in the housing, towards the end of the housing from which the filter element is inserted into the housing. The support surface can be provided by a shoulder or ledge on which the filter element support can rest. The support surface can be continuous around the periphery of the housing. It can just be provided at predetermined positions appropriate for engaging the support. A discontinuous support surface can restrict rota
Bateman Alan
Lane Brian
Shaw Paul David
Smith Stephen Nicholas
Wright Kenneth
Domnick Hunter Limited
Pham Minh-Chau T.
Smith Duane
Workman Nydegger
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