Control valves are a crucial component of any hydraulic system. Responsible for controlling the flow, pressure and direction of hydraulic fluids, they are essential for ensuring that fluid flow stays at a set point in order to ensure optimal performance of the machine.
As a result, if there is a fault or failure with a control valve this can have damaging impacts on the operation of the system and present potential health hazards.
There are many different types of hydraulic control valves, configured to suit the requirements of each system. The size and complexity of the system will determine how many valves are needed, and which types of valves are required.
Without the right valve selection, or a malfunctioning valve, the hydraulic system would struggle to function. Whilst it’s important to perform regular maintenance of your system to prevent failures, it’s also crucial to be able to spot the telltale signs that something may be wrong.
In this article, we will look at some of the common symptoms of control valve faults, and how to detect if your valve needs repairing or replacing.
It goes without saying that a sudden change in, or loss of, pressure in a hydraulic system could be down to a number of factors in various components – but it’s worth checking your control valves.
A change in system pressure of fluid flow rate may be shown on the system’s dial indicator, so you can quickly see if the valve is performing outside of expected parameters. For issues where fluid flow has halted completely, it’s a good idea to check that your directional control valves are situated in the correct position.
Internal leakage in a control valve can be a relatively difficult issue to identify. Valves aren’t designed to close completely and therefore do come with an acceptable leakage level.
However, this is capped at a maximum, so should your valve leakage be exceeding this limit then this can cause a multitude of problems and it may be time to repair or replace.
There may be many reasons why a hydraulic control valve can leak internally – from an incorrectly calibrated positioner to a poor actuator set-up and the wear of internal components.
Regardless, internal leaks are more difficult to identify than external leaks but can be diagnosed by a knowledgeable hydraulic technician.
A large majority of external leaks in a hydraulic system are caused by the control valve. When a system begins leaking hydraulic fluid, this can lead to disastrous consequences with great health and safety implications.
Fortunately, external leaks are fairly visible to the eye so can be diagnosed relatively quickly. External leaks can be caused by anything from faulty valve packing and incompatible materials to excessive component wear.
Generally, correct and regular maintenance of the hydraulic system can prevent hydraulic leaks for the most part, by ensuring that seals are in good condition and the equipment has adequate protection from system vibrations. However, if the component or its elements become worn or damaged, it will need to be replaced as opposed to repaired.
A valve that won’t shift is a common problem in hydraulic systems and can be caused by several factors including mechanical failure, contamination or operator failure.
Contamination from hard particles can stop the valve from moving in its required direction and lead to it becoming jammed. If the contamination isn’t removed, the valve can begin to leak and cause further problems. It is therefore important to have the correct contamination control measures in place such as appropriate filtration and planned maintenance schedules.
Often, a sticking valve can be a consequence of overcompensating for a leakage. When a leak is identified, operators typically attempt to offset this by tightening the packing to stop the leak. As valves come with a specific packing torque value, making any changes to this can prevent them from functioning correctly.
As with any other hydraulic component, even the most reliable and high-quality control valves can quite simply just stop working. Wear and tear may cause the component to become fatigued and eventually break down, it could be incompatible with the system, or it may not be calibrated correctly.
In order to ensure the efficiency and reliability of a healthy hydraulic system, it is important that all components are sized correctly for the application. Control valves should be carefully selected depending on their size and process conditions such as flow, media, and temperature.
Valve failure presents many problems for any hydraulic machinery but can be easily prevented by enlisting the help of a hydraulic engineer in the first instance, and performing required maintenance ongoing.
So, you suspect that there may be a fault with your control valve – but can it be repaired or does it need replacing?
Typically, a control valve repair will be the most cost-effective option in most cases – but this does depend on the condition of the valve along with the costs incurred to seek replacement parts and re-build the valve.
Some valves may fail due to something minor such as a broken seal or faulty bolt which can easily be repaired, whereas others may present more complex problems. A valve that has been operational for some time could be nearing the end of its life, and if it is repetitively failing, it will likely work out more cost-effective to replace as opposed to repair it.
Considering the number of different reasons why a valve may fail, it’s always best to seek out the help of a knowledgeable technician who can diagnose the problem and recommend the most appropriate solution.
As an industry leader in the design, build and repair of hydraulic components, Derek Lane & Co are fully equipped with the skills and knowledge needed to perform professional control valve repairs.
Our facility is based in Devon, UK but we can offer timely and efficient services to businesses nationwide. Please get in touch with us today to discuss your requirements.
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