Abstract: A gasket has an eyelet attached to a flat body portion 1 and the eyelet includes primary (6) and secondary (2,3) sealing zones. An annular seal of a rubber sealing material (9,10) is deposited on the eyelet at least between the primary and secondary sealing zones.The seal of rubbery material may also extend over part or all of the secondary sealing portion of the eyelet and may extend on to the body portion.

Abstract: A pleated paper filter element has the configuration of the frustrum of a cone with the pleats extending lengthwise of the sloping wall of the cone and has pleat separation dimples embossed into the paper from which the element is made, the height of said dimples being graduated lengthwise of the element so as to provide controlled pleat separation over at least most of the length of the element.

Abstract: An indicator device for indicating when a prechosen pressure difference has been exceeded comprises a casing having two ports separated by a resilient diaphragm with an aperture therein, and a movable member urged into sealing relation with said aperture so as to prevent leakage therethrough, the configuration of the member and the aperture being selected so that, in use, the application of a prechosen pressure differential between said ports will cause the member to partly pass through the aperture to a position whereat it is retained by the diaphragm, said member being provided with means for indicating that it has been so retained.

Abstract: Gas filtration apparatus comprises a filter element mounted in a casing having an inlet and an outlet so disposed that gas flowing from inlet to outlet is constrained to pass through the filter element, an audible warning device operable by gas flowing through the inlet and means responsive to the difference between the gas pressure at the inlet and the gas pressure at the outlet and arranged to cause the audible warning device to operate whenever said difference exceeds a predetermined value.

Abstract: A screen for use in a silk screen printing process is made by a process comprising the steps of forming a positive image of a desired print, applying it to a screen so as to obstruct apertures therein corresponding to said positive image, filling all unobstructed apertures in the screen with a flexible polymeric material and then removing the positive image.