BS EN ISO 4022:2018 pdf free
BS EN ISO 4022:2018 pdf free.Permeable sintered metal materials – Determination of fluid permeability
The guard ring test head minimizes side leakage by ensuring that the pressure is the same in the inner and outer chambers. On the upperstream face of the test piece, this is achieved by arranging that the port area connecting the upper chambers (as shown in Figure 1) is as large as possible. On the downstream face of the test piece, the inner chamber leads to a flowmeter, usually subject to a small back pressure, and the outer chamber leads to atmosphere via a pressure-equalizing valve. This valve is adjusted to equalize the pressure in the inner and outer chambers. The fitting of a restrictor between the test piece and the flowmeter, to increase the back pressure and thus permit more stable control of the pressure-equalizing valve, is allowed.
However, ideally, the pressure on the downstream face of the test piece should be as near as possible to atmospheric pressure and a restrictor should not be used unless necessary for the adjustment of the pressure drop in the flowmeter.
Toroidal sealing rings (“0”-rings) are recommended for the inner seals. The seals shall be sufficiently flexible to overcome all surface imperfections and lack of flatness of the porous metal. In some instances it might be necessary to load the inner and outer seals separately to ensure leak-free sealing.
Two upper and two lower seals are required and these shall be in line with each other.The permeability of hollow cylindrical test pieces is conveniently measured by clamping the cylinder axially between two flat surfaces and causing the test fluid to permeate outwards through the wall of the cylinder. An example is shown in Figure 2. The flowmeter is placed upstream of the test piece. When clamping the porous metal cylinder under test, sufficiently flexible seals shall be used to overcome surface irregularities so as to ensure leak-free sealing.BS EN ISO 4022 pdf download.
