Analyzing the Importance of Relief Valve

 

Understanding what relief valves are, is extremely important before getting to their working principle. IH relief valves are components used in hydraulic systems to limit the fluid pressure in the part of the circuit they are installed. It is constructed with a ball and poppet as opposed by a spring and installed into a cavity or ported body. Confused, what is poppet? A poppet is a disc or cone-shaped object that tends to sit within an oppositely machined seat and, when forced closed by spring pressure, tends to provide an extremely low leakage.

Relief valves are, in the majority of the cases, installed in a hydraulic system after the pump. Why? Because this location provides the most immediate and directly involved response when the relief valve opens to bleed fluid to the reservoir, resulting in reducing the pressure equal to its spring setting. So, this relief valve opens as the pressure caused by a downstream load or backpressure increases high enough to force the poppet open against the spring,

Relief valves tend to face pressure built up from the very combination of load pressure, back pressure, and the energy required to flow through the valve itself. So, as the valve throws more liquid towards the tank, the rate of the pressure becomes stable since forces of this pressurized fluid counteract the compression rate of the spring. And as this valve is about to open, the pressure rise is increased again as the valve bottoms out and is subjected to various forces of the flow. But as the work pressure decreases, the valve starts to close; it does so at differing rates than what it is opened at.

An important concept to consider in this regard is the factor of hysteresis. The difference between the opening and closing curve is called hysteresis and is an indicative measure of the quality of its construction. So while considering relief valves, keep in mind that higher quality valves with advanced and quality-centric construction will have lower pressure rise with better hysteresis.

Conclusion – We get to the conclusion that relief valves have higher flow capacities because of the amount of work they have to do, as mentioned above in the blog.