Abstract: A filter element comprises a relatively rigid fluid-permeable cylinder (5), around which is provided a body (7) of non-woven fibrous filter material. A jacket (6) of permeable material is positioned around the outer surface of the filter material, and is heat-shrunk onto the filter material in order to hold this under substantially uniform radial compression over the whole of its area.

Abstract: A pressure indicator for use in a pneumatic circuit. A rolling diaphragm (14) is mounted within a housing (9,10) and divides the housing into first and second regions (15,16), one sealed from the other. The diaphragm has an outer sleeve section (18) and a connected inner cup section (19) lying within the outer sleeve section, the outer surface of the cup section and the inner surface of the sleeve section both being subject to pressure in the second region. An indicator (22) is seated within the cup section. The cup section is biased towards the first region against pressure therein, and into a position wherein the indicator lies substantially wholly within the cup section and is shielded from view thereby. The housing has a transparent section through which the indicator may be viewed as it moves out of the cup section in response to increasing pressure differential between the first and second regions.

Abstract: A microporous membrane suitable for use in microfiltration. The membrane is a hydrophilic skinless sheet, formed of polytetramethylene adipamide, either alone, or in admixture with at least one other polyamide.

Abstract: A filter assembly (1) comprises a fluid tight housing (6, 7). First and second coupling means (10 and 11) are provided on the housing, each coupling means providing adjacent flow channels into the housing. A filter element is located within the housing, the element having a fluid tight external wall (20) and a filter medium (19) housed within the wall. A first flow path is established between the first and second coupling means through the filter element, while a second flow path between the first and second coupling means is established within the housing but outside the external wall of the filter element.

Abstract: A method for preparing an alcohol insoluble polymide membrane. An appropriate membrane-forming casting liquid containing the required polyamide is evaporated under conditions of high total humidity and an air flow of less than 305 m/min. (1000 ft/min) in order to form the membrane. Membranes of a single polyamide, e.g. Nylon 6,6 can be formed by the method.

Abstract: A method of detecting oil aerosol in an air flow. The contaminated air is passed between an electrode (11) and an electrically conductive catalyst (14), and an electrical discharge therebetween causes electrostatic precipitation of oil on to the catalyst. Air flow and discharge are stopped, and the catalyst is heated with the air substantially stagnant until the catalytic combustion temperature of the oil is reached. The heat generation due to such combustion is sensed and used to produce an output signal indicative of the quantity of deposited oil.

Abstract: A filter housing comprises a body (1) designed to provide at least one flow path (8) therein. A filter may be secured to the body in operative connection with the flow path. The flow path opens into a substantially planar external face (9) of the body, and behind that external face the body is formed with passages (15a) lying one to each side of the opening, each passage having an internal wedge face facing away from the external face (9) and lying in a plane that makes an acute angle with the plane of the external face. When two such housings are placed with their planar external faces one in contact with the other and with their flow paths in axial alignment, they may be connected together by drawing wedge members (20) into the passages of the respective housings to draw the housings tightly together.

Abstract: A filter pack comprises a first housing member (1) having an inlet port and an outlet port (4) for compressed air; the outlet port being connectable to a piece of equipment, for example a spray gun. A second housing member (6) is removably fitted into the first housing member through an opening (5) therein and has a section (8) protruding from the opening. A retaining ring (12) releasably secures the two housing members together. The second housing member is at least partially filled with activated carbon filter material (18). A wall area (19) of the second housing member is formed with an inlet into the interior thereof, and the wall area combines with part of the first housing member to form a chamber (15) in communication with the inlet and outlet ports. The protruding section (8) of the second housing member has an outlet (9) for connection to an airline, the flow path from the inlet port to the outlet of the second housing member being through the chamber and then through the filter material.

Abstract: Apparatus for removing entrained liquid from a gas stream comprises a cylindrical casing (67) designed to be mounted so that its axis is substantially vertical. An inlet port (62) and a gas outlet port (63) are provided adjacent to the upper end of the casing and drain means (80) are provided at the lower end of the casing whereby separated liquid may be drained therefrom. A gas outlet tube (75) coaxial with the inner surface of the casing, extends downwardly from the upper end thereof, the outlet tube communicating at its upper end with the gas outlet port (63). A plurality of baffles (72) are arranged in an annulus around the outer surface of the outlet tube (75), the baffles being located downstream of the inlet port (62) and shaped to impart a spinning movement to the incoming gas stream. An impingement plate (77) is located downstream of the baffles and has an upper surface extending transversely across the path of the air stream leaving the baffles.

Abstract: A filter element comprises coaxial inner and outer relatively rigid, permeable cylinders (5, 8), each cylinder being circumferentially continuous and sandwiched between the two cylinders, a spirally-wound cylindrical filter structure comprising a plurality of layers of microporous non-woven fibrous material (9), each pair of adjacent layers being separated by a layer of strong, fluid-permeable, flexible support material (10), the filter structure being under substantially uniform radial compression over the whole of its area. The compression is preferably such as to compress the filter structure by from 25% to 45% of its original thickness, and materially increases the efficiency of filters incorporating the structure. A method of effecting the compression during manufacture is also described.