How Does a Hydraulic Check Valve Work?
How Does a Hydraulic Check Valve Work?
Hydraulic check valves are hydraulic circuit elements that allow passage to the fluid in one direction. They are produced with or without spring depending on the place of use. While non-spring check valves are only suitable for vertical installation, spring check valves can be used in any desired installation. Spring pressures of check valves vary according to their intended use.
The following applications can be given as examples of usage areas;
by-pass of another circuit element
Blocking of flow in one direction
Generating a certain counter pressure in circuits
Check valves are produced in different mounting types, while a line type check valve shown in the picture above is also possible to see the plate type and drill type check valves seen in the pictures below.
It is possible to see check valves as auxiliary elements in other hydraulic circuit elements. Especially, it is a common situation that a check valve is placed inside the throttle valves so that they can throttle in one direction. This type of throttle valves is referred to in the market as "check throttling".
In the one-way throttle valve in the figure above, as it can be understood from the internal structure and the circuit symbol, while passing through the oil restrictor coming from port number 2, it passes by bypassing the oil restrictor coming from the port number 1, such throttling task is only from port no 2 to port no. happens in the direction of passage.
Sample Application 1
The purpose of the check valves is to separate the two hydraulic power sources to prevent them from damaging each other. We can evaluate these examples under the heading of blocking of flow in one direction. While the check valves shown with number 1 are used to prevent the high pressure pump from pressing and damaging the low pressure pump in double pump application, the check valve shown with number 2 allows the pump to supply oil to the line by putting the pump to the line, and when the electric motor is stopped, the oil in the accumulator in the line will cause the pump to reverse. It was used to prevent forced discharge.
Sample Application 2
The check valve shown with number 3 in the hydraulic circuit diagram and filter cross-sectional picture is used to bypass another circuit element, as in the throttle valve. But there is a difference here. In the throttling example, while blocking in one direction and providing free passage in the other direction, the by-pass of the filter here depends on the condition of the filter being clogged. This can be controlled very simply by the spring pressure of the check valve. If the filter starts to clog with dirty particles, it will create a resistance in front of the oil going to the tank and cause an increase in pressure. If the filter element is not replaced, a return line filter designed for low pressure conditions of this pressure will cause damage to the weak body of the filter. In this case, a check valve placed in the filter will prevent the body from being exposed to high pressure by bypassing the filter when it reaches the opening pressure. Of course, this is just a precaution for the filter body against potential high pressure hazards. If the filter element is not replaced, the system will continue to work with the dirty oil that does not pass through the filter, and all hydraulic circuit elements will be damaged. In order to keep track of the replacement time of the filter element, manufacturers attach various visual or electrical stimulants to their filter housings.