The amount of time required to open the valve is dependent upon the flow rate of the pump and backpressure in the system. When the inlet supply pressure is decreased below the pre-set pressure, the valve will close again and an internal check valve will open permitting fluid flow from the actuator back through the valve. This will allow the sequenced devices to return to pre-actuation condition. Pressure limiting valve (PLV) is a manually adjustable normally open valve that limits the pressure in a branch of the circuit and will maintain a lower pressure on that branch than the main circuit pressure.
Pressure reducing valve (PRV) is a manually adjusted normally open valve that reduces pressure in a branch of the circuit and will maintain a lower pressure on that branch than the main circuit pressure.
It will allow flow to pass from the inlet port thru the valve to the outlet port and build pressure downstream in the system. As the pressure in the downstream system increases, backpressure on the outlet port of the system will close the valve and block off the flow. It will maintain a lower pressure setting than the main system pressure by monitoring the reduced pressure system. If the reduced pressure system starts to flow again, as in a leak in the system, allowing the pressure on valve to drop below the pre-set pressure, the valve will re-open to allow make up flow from the main system until the pre-set pressure is again reached (assuming that the flow on the reduced pressure portion of the system is slow enough for the power supply to overcome the pressure loss, or the flow stops) and again closes. When the inlet pressure is removed, the valve will open and allow the fluid to return to tank through the valve. As this valve will re open and reset if there is a downstream pressure drop, it will work well with both single and double acting actuators. Speed control valve is an adjustable device that controls speed of an actuator by restricting the flow of the fluid. The valve is typically manually adjusted to obtain required actuation speed. The two basic types of speed control valves are described next.
It will allow flow to pass from the inlet port through the valve to the outlet port and build pressure in the downstream system. As the pressure in the downstream system increases, backpressure through the valve causes it to close and block off flow. The inlet pressure from the main system will keep the flow blocked, and therefore cannot re-open to compensate for pressure loss in the downstream pressure limited system. When the inlet pressure is removed, the valve will re-open and allow the down stream fluid to return to tank through the valve. As this valve, by itself is held closed by the main system pressure. It is best suited for use with single acting actuators. Contact your VektorFlo® sales team for information and recommendations when installed in a double acting system.
Hydraulic Clamping Fundamentals Aug 09 Rev - D
8 of 40
Made with FlippingBook - Online Brochure Maker