In order to operate the secondary unit, the fluid must flow through the sequence valve. The valve is located so that the primary unit moves the plunger as it completes its operation. If the pressure
drops below 2,200 psi
, the priority valve closes and no fluid pressure flows to the noncritical systems.
What is a sequence valve?
A sequence valve is
a pressure-operated, normally closed, poppet or spool valve that opens at an adjustable set pressure
. Some designs use a spring acting directly on the spool or poppet, others are pilot-operated. A sequence valve always has an external drain port to keep from trapping leakage oil.
What is a priority valve?
Description. Priority valves are
used to provide a hydraulic function in a load sensing system with a priority flow
.In principle, they operate like a 3-way flow control valve that always supplies the actuator that has priority with the required flow rate, and passes the remaining flow to other actuators.
What is priority valve in aviation?
A priority valve
gives priority to the critical hydraulic subsystems over noncritical systems when system pressure is low
. For instance, if the pressure of the priority valve is set for 2,200 psi, all systems receive pressure when the pressure is above 2,200 psi.
What are the differences between a pressure reducing valve and a sequence valve?
A sequence valve is a pressure control valve that is used to force two actuators to be operated in sequence. They are similar to pressure relief valves. Instead of sending flow back to tank, a sequence valve
allows flow to a branch circuit, when a preset pressure is reached
.
Which valve is best for flow control?
For flow control applications where a ball valve is possible, such as filling a tank to a reasonable degree of accuracy,
a trunnion or v-port ball valve design
is usually the best choice.
What is a priority flow control valve?
The model OP51FC is a
pressure compensated swing arm adjustable flow control valve
. By swinging the arm thru 90 °, the flow out the CF or controlled low port can be varied within the range given in the specification. Any remaining flow is bypassed to the EX or excess flow port.
What is the purpose of a sequence valve?
Sequence valves can be
used to sense pressure (port 1) in one circuit and then open and supply oil to a secondary circuit (port 2) at a predetermined pressure
. A typical application would be when maintained clamping pressure is required in the primary circuit while work is being performed in the secondary circuit.
What is the function of unloading and sequence valve?
Type of sequence valve that uses a
remote pressure signal to unload a circuit
. Commonly used for unloading an accumulator charging circuit or unloading a pump to tank at minimum pressure.
What is the function of time delay valve?
Time delay valve is used
to delay the output signal
. The time delay valve is actuated by a pneumatic signal through the tank after a preset time delay has elapsed. The returned to the normal position via return spring when the signal is terminated.
What is a poppet type valve?
A poppet valve consists of
an orifice that is opened and closed by raising and lowering a sealing surface onto the orifice
. It usually has an internal spring that holds the valve in the closed position. When the spring force is overcome, the sealing surface lifts off the orifice and the valve opens.
What is the valve margin?
A valve margin is defined.
Between the top of the valve and the edge of the face is the width of the valve head
. Preignition and valve damage are caused by too narrow a margin.
What is the function of pressure relief valve?
A pressure relief valve, at times called a relief valve, is one that is
used to control or put a limit on the pressure within any given system to prevent it from building up and causing damage to equipment or causing more serious hazards
.
Is connected between pump and tank?
Deenergizing the
solenoid
on the solenoid-operated relief valve connects pump flow to tank and the hydraulic motor coasts to a stop. … A normally open solenoid-operated relief valve lets flow from the pressure-compensated pump go to tank until the electric drive motor is up to speed.
How does sequence valve work?
A sequence valve is a pressure valve
designed to open when its set pressure is reached
, providing a path of flow alternate and sequential to the primary circuit. … used for automated hydraulic functions, especially those which occurred naturally from lowest to highest pressure.
What are the factors to consider when selecting a control valve?
- Media Type. The characteristics of the liquid or gas type being controlled will determine the valve material that should be used. …
- Application Conditions. …
- Valve Function. …
- Actuation Method. …
- Maintenance Requirements.
