Pressure-control valves are found in virtually every hydraulic system, and they assist in a variety of functions, from keeping system pressures safely below a desired upper limit to maintaining a set pressure in part of a circuit.
Goto SUPCON to know more.
Relief Valves
Most fluid power systems are designed to operate within a preset pressure range. This range is a function of the forces the actuators in the system must generate to do the required work. Without controlling or limiting these forces, the fluid power components (and expensive equipment) could be damaged. Relief valves avoid this hazard. They are the safeguards which limit maximum pressure in a system by diverting excess oil when pressures get too high.
Cracking pressure and pressure override. The pressure at which a relief valve first opens to allow fluid to flow through is known as cracking pressure. When the valve is bypassing its full rated flow, it is in a state of full-flow pressure. The difference between full-flow and cracking pressure is sometimes known as pressure differential, also known as pressure override.
Direct-acting relief valves. A direct-acting valve may consist of a poppet or ball, held exposed to system pressure on one side and opposed by a spring of preset force on the other. In an adjustable, normally closed relief valve (Fig. 1), the force exerted by the compression spring exceeds the force exerted by system pressure acting on the ball or poppet. The spring holds the ball or poppet tightly seated. A reservoir port on the spring side of the valve returns leakage fluid to tank.
A Pressure Reducing Valve holds a consistent set point downstream of the valve.
For reducing pressure in high pressure application, you can use a High Pressure Control Valve package set up for pressure reducing application.
In this video, we're going to look at the production flow through this Pressure Reducing High Pressure Control Valve Package configured with a Diaphragm-Controlled High Pressure Pilot.
The supply gas regulator reduces the upstream pressure to 30 PSI;to provide supply pressure to the pilot after passing through a filter.
When the adjustment screw is unthreaded, there is no downward pressure on the pilot diaphragm assembly. Once the adjusting screw is threaded farther into the bonnet, the spring puts pressure on the assembly, which positions the pilot plug to open the flow of supply pressure into the control valve actuator.
This supply pressure pushes up on the control valve diaphragm working against the tension of the spring. This opens the valve and allows upstream pressure to move downstream.
Next, downstream gas moves through the sense line protector. This device blocks pressure to the pilot when it exceeds the working pressure of that pilot.
Now, supply pressure is blocked from going into the control valve actuator, and instead the diaphragm pressure is rerouted out through the pilot and vented.
In this example, the downstream pressure will hover around 99 PSI, where the valve is barely open, to 100 PSI, when the valve is closed.
This can also be seen on the travel indicator as it only moves between the lower two marks.
If you want to learn more, please visit our website pressure control valve air.
As this cycle repeats, liquids continue to fall out of the supply gas into the drip pot where it will need to be drained regularly, depending on the conditions.
In this video, we're going to look at the production flow through this pressure reducing control valve package, configured with a Bellows Controlled High Pressure Pilot.
Beginning with the control valve in a closed position and the adjusting screw not yet calibrated to a desired set point, the upstream pressure begins to flow ' in this example, up to a pressure of 400 PSI.
Upstream pressure flows into the Drip Pot which knocks out liquid from the supply gas which could be detrimental to other instruments.
The supply gas regulator reduces the upstream pressure to 30 PSI to provide supply pressure to the pilot.
When the adjustment screw is unthreaded, there is no downward pressure on the pilot diaphragm assembly. Once the adjusting screw is threaded, the spring puts pressure on the assembly which positions the pilot plug to open the flow of supply pressure into the control valve actuator.
This supply pressure pushes up on the control valve diaphragm working against the tension of the spring.
Next, downstream gas moves through the sense line protector. This device protects the pilot from over pressurization. It blocks the downstream pressure when it exceeds the adjustable limit and reopens when inlet pressure drops below the limit.
As the sense pressure approaches the set point, it causes the bellows to contract, actuating the bellows stem to move it upward against the diaphragm assembly.
Once pressure has vented, and there is no longer enough pressure to overcome the pilot spring, the pilot diaphragm assembly will move back down.
The rapid but stable repositioning of the pilot plug produces a throttling action, and the valve will open and closed by only a small percentage to maintain the set point.
As this cycle repeats, liquids continue to fall out of the supply gas into the drip pot where it will need to be drained regularly, depending on the conditions.
If you are looking for more details, kindly visit flow control valve how does it work.