pilot valves are valves which are used to control other valves. pilot valves in the actuator lines control the supply of air or liquid going to the actuators. the fill valve in a toilet water tank is a liquid level-actuated valve. when a high water level is reached, a mechanism shuts the valve which fills the tank.
the most common diaphragm valves use pneumatic actuators; in this type of valve, air pressure is applied through a pilot valve into the actuator which in turn raises the diaphragm and opens the valve. this type of valve is one of the more common valves used in operations where valve speed is a necessity.
the most common final control element in the process control industries is the control valve. the control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.
a reduced pressure zone device rpzd, rpz, or rpz valve is a type of backflow prevention device used to protect water supplies from contamination. rpzds may also be known as reduced pressure principle rp , reduced pressure principle backflow prevention devices, reduced pressure zone assemblies rpza , or reduced pressure principle assembly rppa .. asse standard 1013 - reduced pressure .
each brake reservoir stores air at a pressure of 7 bar and is fed via a pressure reducing valve off the main reservoir pipe. the driver's brake handle passes control voltages down three wires to each ep control valve, which allows air from the brake reservoir to pass into the brake cylinder, thereby activating the disc brake.
water and gas taps have adjustable flow: gate valves are more progressive; ball valves more coarse, typically used in on-off applications. turning a valve knob or lever adjusts flow by varying the aperture of the control device in the valve assembly. the result when opened in any degree is a choked flow.
control valves can also work with hydraulic actuators also known as hydraulic pilots . these types of valves are also known as automatic control valves. the hydraulic actuators respond to changes of pressure or flow and will open/close the valve. automatic control valves do not require an external power source, meaning that the fluid pressure .
two types are found: the pressure reduction regulator and the back-pressure regulator. a pressure reducing regulator is a control valve that reduces the input pressure of a fluid or gases to a desired value at its output. it is a normally-open valve and is installed upstream of pressure sensitive equipment.
choke valve, butterfly valve used to limit air intake in internal combustion engine. not to be confused with choke valves used in industrial flow control. clapper valve: a type of check valve used in the siamese fire appliance to allow only 1 hose to be connected instead of two the clapper valve blocks the other side from leaking out .
when the throttle is closed, a vacuum forms in the manifold. this in combination with the pressurized air from the turbocharger moves the piston in the valve up, releasing the pressure into the inlet of the turbo recirc. or the atmosphere bov .
the quantity of bleed air flowing to the a/c pack is regulated by the 'flow control valve' fcv . one fcv is installed for each pack. a normally closed 'isolation valve' prevents air from the left bleed system from reaching the right pack and vice versa , although this valve may be opened in the event of loss of one bleed system.
air or control signal failure to close' - on failure of compressed air to the actuator, the valve closes under spring pressure or by backup power. air or control signal failure to open' - on failure of compressed air to actuator, the valve opens under spring pressure or by backup power.
some pressure independent control valves enable fan coils and air handling units to have the maximal flow set exactly at design flow. switching a traditional control valve to a pressure independent type should not be seen as only benefiting the mechanical contractor, by reducing installation cost. it benefits the systems integrator and most importantly the client, ensuring both improved .
a blowdown valve bdv is a type of shutdown valve designed to depressurize a pressure vessel by directing vapour to a flare, vent or blowdown stack in an emergency. bdvs fail-safe to the open position upon failure of the control system. the type of valve, type of actuation and performance measurement are similar to an esd valve.
a reduced pressure zone device is a type of backflow prevention device used to protect water supplies from contamination. rpzds may also be known as reduced pressure principle, reduced pressure principle backflow prevention devices, reduced pressure zone assemblies, or reduced pressure principle assembly. asse standard 1013 - reduced pressure backflow assembly asse standard 1015 - double check valve assembly asse standard 1020 - pressure vacuum breaker asse standard 1047 - reduced pressure detec
a type of externally equalized thermal expansion valve, known as the block type valve, which features an internal sensing bulb often the valve's metal body, particularly when a stable and hunting-free refrigerant flow control is required , located inside the suction line connection and in constant contact with the refrigerant that flows out of .