Abstract: A differential pressure indicator has a piston across which inlet and outlet pressures are applied with a spring preventing movement of the piston until a predetermined differential pressure is exceeded. At this point, a port is opened to allow the inlet pressure to be applied to an indicator button to move the indicator button from a retracted position to an operative extended position to indicate that the pressure differential has been exceeded. The use of fluid pressure to operate the indicator button applies a large force to the indicator button and allows it to be securely held in the inoperative position to guard against accidental movement by high G-forces.

Abstract: A double differential pressure indicator has a housing containing two pistons arranged in contiguous bores and biased by a single spring extending between opposed ends of the pistons. The differential pressure is applied across both pistons and as the pressure differential increases to a first predetermined difference one piston moves to operate a first indicator which may, for example, be a reed switch. As the differential pressure further increases, the second piston moves to operate a second indicating device which may be a button. In an alternative arrangement, both indicating devices operate at the same differential pressure.

Abstract: In an aircraft, a pressure swing adsorption system (23) is used both for removing carbon dioxide and water vapour from recycled cabin air and for producing in an emergency oxygen from pressurized engine bleed air.

Abstract: In an aircraft, a pressure swing adsorption system (23) is used both for removing carbon dioxide and water vapour from recycled cabin air and for producing in an emergency oxygen from pressurized engine bleed air.

Abstract: The removal of components from fluid mixtures in aircraft utilizes an adsorbent bed which is regenerated by passing dry ambient air through the adsorbent bed when the aircraft reaches a height at which such dry ambient air is available. An example of mixtures that can be treated in this way are water/oil mixtures, air/water vapor mixtures and air/odor mixtures. By periodically regenerating the adsorbent bed in this way, an adsorbent bed of small size can be used but yet have a substantial life.

Abstract: A pressure indication device comprises a housing including a bore in which is received a slidable piston. The piston has two end faces, one of which is for connection to a source of fluid at higher pressure and the other of which is for connection to a source of fluid at lower pressure. The device produces an indication when the pressure differential reaches a predetermined value. In an inoperative position of the piston, a portion of the upstream face co-operates with the bore to provide a face seal which reduces leakage between the bore and the piston and which also reduces the effective area of the upstream face. In addition, a labyrinth seal is provided between the bore and the piston. When the predetermined pressure is reached, the piston moves, and as it does so, the effective area of the upstream face is increased.

Abstract: A differential pressure indicator is of the type which uses a magentically attracted spring loaded pop-up button to indicate when the pressure difference between two fluids reaches a predetermined difference. In order to reduce or eliminate false readings caused by fretting between the button and a housing passage in which it slides the button and the passage have a square cross-section to prevent rotation.

Abstract: An automatic bleed valve bleeds gas from a liquid reservoir. It comprises a housing having a passage extending between an inlet and an outlet with the passage including a bore in which a piston is slidably received. The piston includes a capillary providing fluid communication between the inlet and a chamber formed in the passage adjacent the outlet. The piston is biased into an upstream position in which gas entering the inlet passes through the capillary to the chamber and thence to the outlet. However, the passage of liquid through the capillary so increases the pressure drop across the piston as to move the piston to a downstream position in which the piston closes the outlet to prevent communication between the chamber and the outlet, thus closing the valve.

Abstract: An aircrew life support system has an on-board oxygen generating system (OBOGS) connected for delivering oxygen-enriched product gas to a breathing demand regulator and a plenum storage container. The concentration of oxygen in the product gas is sensed by a gas concentration sensor which supplies signals to an electronic control unit (ECU). The ECU outputs signals for switching a control valve which controls product gas to be delivered to the regulator from either the OBOGS or the storage container. The ECU also outputs signals to a charge valve which is opened to allow product gas from the OBOGS to charge the storage container when product gas enriched with oxygen above a predetermined concentration is being delivered by the OBOGS and there is excess capacity over the demand requirements at the regulator.