What is a shuttle valve? Which logic valve is known as a shuttle valve
The shuttle valve is also called a double check valve, a shuttle valve has two inlets and one outlet. If any of the inlets is unloaded the flow will be shut off in that direction and it will be open from the loaded one to the outlet. A shuttle valve may be installed, for example when a power unit or control unit is to be actuated from two points, which may be remote from one another. A shuttle valve is a pressure operated valve, these valves can separate the normal hydraulic system from the emergency pneumatic system. The air pressure in the lines will be removed through the vent port of the control valve if the control handle is returned to the normal position. The working of the shuttle valve is related to the OR logic function. If we supply fluid under pressure to any of the two inlet ports, then there will be a supply from the outlet port
How shuttle valves are constructed
Shuttle valves are commonly used for pneumatics and little use for the hydraulic system. Inside the valve body, the shuttle valve has a ball or poppet. The ball poppet closes the other inlet port if the fluid is supplied to any of the inlet ports, and the fluid will flow to the cylinder port. Shuttle valve has two fluid inlets P1 and P2 as it is shown in the below figure and there is only one fluid outlet A. when compressed fluid enters through P1 the sphere will seal and block the other inlet P2. So the fluid will flow from P1 to A. when the contrary happens the sphere will block inlet P1 and will allow the fluid to flow from P2 to A.
What is a twin pressure valve
The twin pressure valve has two inlet ports, these valves operation is related to AND logic function. The flow from the outlet is only possible if the fluid under pressure is supplied to both the inlet ports. A twin valve has a spool inside the valve body and when the fluid is supplied from one inlet port then the spool will close the outlet. The outlet port will only open if the fluid is supplied from both the inlet port.
What is sequence valve and what are they used for
Sequence valves are pressure control valves, sequence valve is normally a closed valve with the pilot line to sense the inlet pressure. These valves are used in the hydraulic system, sequence valves which are used in hydraulic systems can do many operations. The function of the sequence valve is to direct the flow in a predetermined sequence.
How does a shuttle valve work? What does a shuttle valve do
The shuttle valve is a pneumatic OR valve and is also called as a double check valve. The valve consists of a valve body and a synthetic ball or cuboid valving element moving inside the bore in the valve housing and it is shown in the below figure. In the below figure we can see that the valve has two inputs and one output the inputs are 12 and 14 and 2 is the output. If the compressed air applied to input 12, then the ball seals of the other input 14, and the compressed air will flow through input 12 to output 2. If the compressed air is applied to the input 14, then the ball seals of the other input 12, and then the compressed air will flow from input 14 to output 2. If the compressed air is applied to both the ports, air moves to 2 either from 12 or 14 or from both. There are two inlets in the shuttle valve so if one the inlet loses the pressure the other one will be a backup for it.
What are the applications of a shuttle valve
- By using a shuttle valve in a machine we can operate more than one switch and each switch can be placed at any suitable location. This would increase the safety and reliability of the machine. So because of this shuttle valves are used in many industrial types of machinery.
- Shuttle valves can be used in standby systems, so in operation, if there is a case of compressor failure then the standby tank will take over the function from the shuttle valve. Shuttle valve will only take over the standby system if the compressor pressure is re-established
- Shuttle valve can be used with pumps it must be used regardless of whether the speed is controlled in one direction or both. Its purpose is to pick a pressure signal from the cylinder port with the higher pressure, according to whether the cylinder is extending or retracting, and still to vent the sensing line in the valve neutral. Without the shuttle valve and the open cylinder ports on the 4-way valve, the pump cannot unload when it becomes deadhead in the neutral.
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