Pilot Operated Check Valves: Fill & Download for Free

For cabin fires and smoke, the Oxygen masks can help you very little. The masks are generally dropped automatically when the cabin altitude (not the aircraft altitude) reaches 14,000 ft or they are manually dropped down by a pilot operated switch. In gas type oxygen systems, the doors which hold the masks are opened pneumatically when the previously mentioned requirements are met. The passengers then have to pull the mask from their hung position to extend the cord. The extension will start the Oxygen flow due to the opening of a check valve. In the chemical type system which is the most common type used in modern airliners, the doors are opened by solenoids. The way to operate remains the same as that of a gas system. The advantages of a chemical system is their low maintenance costs and low risks of a fire.The transparent bag you see right above the trade mark yellow mask is called a rebreather bag. The air in the cabin together with the air exhaled by the passengers gets mixed with the Oxygen in this bag. So, if there is smoke in the cabin, they will pass into the mask and will offer no help. The supplemental Oxygen is only there for reasons of depressurization issues and usually lasts for 15 minutes, which is more than enough for the pilots to descend to a safe altitude.A chemical type Oxygen mask. The cylinder is the chemical Oxygen generator.

a relief valve can be actuated directly or piloted, wheras a pilot operated valve is more general it could a directional valve, a check valve etc… and by pilot opertaed is that it has a hydraulic command that will operate it wether by pressure or through another direct/electric operated valve

Valves can be categorized into the following basic types:Ball valve, for on/off control without pressure drop, and ideal for quick shut-off, since a 90° turn offers complete shut-off angle, compared to multiple turns required on most manual valves.Butterfly valve, for flow regulation in large pipe diameters.Ceramic Disc valve, used mainly in high duty cycle applications or on abrasive fluids. Ceramic disc can also provide Class IV seat leakageClapper valve, Used in appliances like the Siamese fire appliance to allow only 1 hose to connected instead of two (the clapper valve blocks the other side from leaking out.Check valve or non-return valve, allows the fluid to pass in one direction only.Choke valve, a valve that raises or lowers a solid cylinder which is placed around or inside another cylinder which has holes or slots. Used for high pressure drops found in oil and gas wellheads.Diaphragm valve, which controls flow by a movement of a diaphragm. Upstream pressure, downstream pressure, or an external source (e.g., pneumatic, hydraulic, etc.) can be used to change the position of the diaphragm.Gate valve, mainly for on/off control, with low pressure drop.Globe valve, good for regulating flow.Knife valve, similar to a gate valve, but usually more compact. Often used for slurries or powders on/off control.Needle valve for accurate flow control.Pinch valve, for slurry flow regulation and control.Piston valve, for regulating fluids that carry solids in suspension.Plug valve, slim valve for on/off control but with some pressure drop.Poppet valve, commonly used in piston engines to regulate the fuel mixture intake and exhaustSpool valve, for hydraulic controlThermal expansion valve, used in refrigeration and air conditioning systems.Pressure Reducing ValveSampling valvesSafety valveSpecific types[edit]Aspin valve: a cone-shaped metal part fitted to the cylinder head of an engineBall cock: often used as a water level controller (cistern)Bibcock: provides a connection to a flexible hosepipeBlast valve: prevents rapid overpressuring in a fallout shelter or a bunkerBoston valve: three-part two-port check valve used on inflatable boats, air mattresses, airbeds etc.; available in two sizes, normal and smallCock: colloquial term for a small valve or a stopcockDemand valve: on a diving regulatorDouble beat valveDouble check valveDuckbill valveFlipper valveFlow control valve: an application which maintains a variable flow rate through the valveHeimlich valve: a specific one-way valve used on the end of chest drain tubes to treat a pneumothoraxFoot valve: a check valve on the foot of a suction line to prevent backflowFour-way valve: was used to control the flow of steam to the cylinder of early double-acting steam enginesFreeze seal/Freeze plug: in which freezing and melting the fluid creates and removes a plug of frozen material acting as the valveGas pressure regulator regulates the flow and pressure of a gasHeart valve: regulates blood flow through the heart in many organismsHydrodynamic vortex valve: a passive flow control valve that uses hydrodynamic forces to regulate flowLarner–Johnson Valve: needle control valve often in large sizes used in water supply systemsLeaf valve: one-way valve consisting of a diagonal obstruction with an opening covered by a hinged flapPilot valve: regulates flow or pressure to other valvesPinch valve, "beach ball valve": simple, single-part two-port check valve made from soft plastic and molded on to inflatable units such as beach balls, air mattresses, water wings; can be inflated by pump or by mouth.Plunger valve: To regulate flow while lowering the pressurePoppet valve and sleeve valve: commonly used in piston engines to regulate the fuel mixture intake and exhaustPressure regulator or pressure reducing valve (PRV): reduces pressure to a preset level downstream of the valvePressure sustaining valve, or back-pressure regulator: maintains pressure at a preset level upstream of the valvePresta and Schrader valves are used to hold the air in bicycle tiresReed valve: consists of two or more flexible materials pressed together along much of their length, but with the influx area open to allow one-way flow, much like a heart valveRegulator: used in SCUBA diving equipment and in gas cooking equipment to reduce the high pressure gas supply to a lower working pressureRocker valveRotolock valveRotary valves and piston valves: parts of brass instruments used to change their pitchRupture disc: a one time use replaceable valve for rapid pressure relief, used to protect piping systems from excessive pressure or vacuum; more reliable than a safety valveSaddle valve: where allowed, is used to tap a pipe for a low-flow needSafety valve or relief valve: operates automatically at a set differential pressure to correct a potentially dangerous situation, typically over-pressureSchrader valve: used to hold the air inside automobile tiresSolenoid valve: an electrically controlled hydraulic or pneumatic valveStopcock: restricts or isolates flow through a pipeSwirl valve: A specially designed Joule-Thompson pressure reduction/expansion valve imparting a centrifugal force upon the discharge stream for improving gas–liquid phase separationTap (British English), faucet (American English): the common name for a valve used in homes to regulate water flowTesla valve: A form of check valve with no moving parts, invented by Nikola Tesla for use with fluids.Thermal expansion valve, used in air conditioning and refrigeration systems.Thermostatic mixing valveThermostatic radiator valveTrap primer: sometimes include other types of valves, or are valves themselvesVacuum breaker valve: prevents the back-siphonage of contaminated water into pressurized drinkable water supplies