Home » How to fit a check valve
Imagine hydraulic piping where the gravitational return of the fluid must be prevented internally: the solution is to fit a check valve at the start of the piping, which prevents the fluid from travelling in an opposite direction to the one required.
Check valves, which are also called non-return valves, are made in a way that only allows liquids to flow in one direction. The fact of being one-way is the determining element for their use.
Check valves are essentially made up of a mobile element, called disc, and often (but not always) a spring and flange. How they work is easy to understand: they use the difference in pressure between the upstream and downstream sections of the disc. When the downstream pressure is higher than the upstream pressure, the disc moves from its seat and allows fluid to pass. The fluid pressure moves the disc, overcoming its weight and the force of the spring (if present), to open passage. If, on the other hand, the upstream pressure is higher than the downstream pressure, the fluid tends to return towards the downstream section, which pushes the disc (with the help of the spring if present) back into its seat, so closing the valve. In general there is an arrow on all check valve bodies that indicates the flow direction.
Check valves are automatic, therefore all that needs to be done while fitting is to make sure that the arrow on the body is pointing in the same direction as the fluid circulating in the system. All our valves are tested before being marketed, but it is still a good idea to check valve operation beforehand by pushing the disc in the direction indicated by the arrow on the body.
This is just a simple precaution to make sure there are no foreign bodies inside the valve that may prevent the mobile parts from operating correctly.
This is also why it is important to protect the valves before fitting them, so as to prevent dust and impurities from stopping correct valve opening and closing. Once this check has been done, you can connect the valve to the circuit.