Within a hydraulic system, there has to be hydraulic system pressure – it is the pressurised fluid that creates the fluid power that transfers the force into mechanical power.
However, there are usually set parameters of pressure that will keep a hydraulic circuit working efficiently. If the pressure setting is too low the power will be compromised, or fail. Conversely, too much pressure can not only damage the parts of the hydraulic system but can also be dangerous within some hydraulic systems.
This is why hydraulic pressure control valves and hydraulic pressure relief valves are a part of almost every hydraulic system. They help to keep system pressure under the upper limits and also maintain pressure within a hydraulic circuit.
This article will go through the different types of valves, explain how they work and look at the importance of regular calibration.
Types Of Hydraulic Pressure Control Valves & How They Work
Relief Valves
A relief valve, also sometimes called a safety valve, helps to reduce system pressure to avoid the damage that can be caused to the hydraulic system if the pressure becomes too high. They are commonly composed of a spring-loaded piston inside an orifice. The bottom of the piston will be pushed up when the pressure in the system reaches a particular point so the pressurised fluid can enter the cylinder through the orifice and provide pressure relief.
Pressure Reducing Valves
These self-operating valves help to keep pressure at a constant level. They are also known as pressure-reducing valves or pressure-reducing regulators. They allow fluid or oil to enter until a predetermined pressure is reached further along the system, once it has it stops the flow usually with a pintle and a diaphragm.
Sequence Valves
Sequence valves are similar to pressure relief valves only they are specifically used in fluid power systems where there are two circuits and two actuators both powered by a single pump and so the flow needs to be directed in a sequence that is related to the fluid pressure. From the one actuator until it reaches a certain maximum pressure or level, when the sequencing valve will then direct it to the second actuator.
Proportional Control Valves
As the name suggests, proportional control valves allow for a variable flow control rate rather than a simple open or closed valve. They can do this with a restrictor which enables any number range of spool positions and there for any flow rate.
Importance of Proper Calibration
As we have seen, hydraulic pressure control valves and pressure relief valves ensure that hydraulic systems work efficiently, safely and without putting undue pressure on the components of the system thus helping to ensure its longevity.
However, the valves are only effective if they are correctly calibrated. Incorrectly calibrated valves cause numerous problems and system errors such as incorrect flow rate sequence valve name, temperature and pressure.
This, in turn, can cause system inefficiency, costly repairs and hazardous working conditions.
As a general rule, your hydraulic valves, especially your pressure relief valves, should be calibrated by a qualified professional hydraulic engineer at least annually. Some systems may require more frequent calibration.
Conclusion
Any hydraulic system is only ever as efficient as its least efficient component and hydraulic pressure relief valves and control valves are no exception. All the different types of control and hydraulic relief valves have an important role and it is essential, not only for the performance of your hydraulic systems but for the safety of your workers and your budget that you ensure they are well maintained and calibrated.
If you have any questions, want to book your annual service and calibration or need to order replacement pressure control valves get in touch with our team at MCH Hydraulics.