Safe Operation of Hydraulic Equipment

How to to operate hydraulic equipment safely

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All designs have different duty requirements

hydraulic power units

The design and operation of every piece of hydraulic equipment will be different. Some machines are designed for only 250 hours of intermittent, full load working and some for 10000 hours of continuous, full load operation. The components used, circuit designs, and maintenance procedures will be different for each system, depending on its needs. It is therefore important that users do not operate equipment designed for intermittent use, continuously, for example.

Production vs development designs

The risk of failure or accident will always be much higher with new, development or custom machines, than on fully proven production machines. It is important to understand what type of equipment you are working on and take extra precautions if there is no long history of a design working safely. Development environments normally have far more restrictions for public access and often the operators are fully protected from the hydraulic equipment as it will be located inside a sealed test cell. When buying equipment it is vital to know whether it is fitted with appropriate guarding or requires additional operator protection screens.

Risk assessments and training

Make sure that someone has completed a proper risk assessment and that the assessment gets reviewed every time any changes occur.

Make sure that all operators and maintenance staff have been appropriately trained for the equipment being used.

See our safety training modules here

Be aware of the potential risks

Fluid power risks

Hydraulic accumulators retain energy even when the power is turned off. Unsupported cylinders retain potential energy and must be lowered safely to mechanical stops. Small temperature changes will generate high pressures in sealed volumes.

Make sure you complete the full safety and potential risks training sections to understand these issues. Check the equipment you are using to see which components or features it contains and where any risk points may be.

Beware irregular procedures

Studies have shown that 60-70 % of injuries occur from irregular procedures are carried out. This may be, for example, when the equipment is not being used in the correct way, perhaps because a small fault has occurred somewhere and a physical or procedural change has been implemented to work around this. It could be worthwhile remembering this and always taking extra precautions when working in unusual environments etc.

Hydraulic hose failures

hydraulic hose

Hydraulic hoses require periodic replacement and must be correctly installed and regularly inspected for wear or damage. Make sure that someone is responsible for checking each hose and that they are completing this work effectively. But even if they are, it is always recommended that the operator checks the hoses and equipment every time the machine is started always keep an eye out for unexpected damage or wear.

Make sure that all operators and other personnel are adequately protected against the risk of flying ends and oil injection injuries.

Maintain fluid cleanliness at all times

fluid contamination

Over 80% of failures are caused by fluid contamination. Dirt can enter the fluid from the atmosphere via the air breather or cylinder rods etc. Poor housekeeping and dirty environments will increase the risk of contamination getting into the fluid so it is vital that operators maintain the cleanest local environment possible.

Dirt is also generated by components when they are operated unusually harshly or outside of their normal working conditions. Take care with how you operate equipment and it should last much longer between failures.

Performance and calibration limits

Users must understand the performance limits and normal operating conditions for the equipment. Working outside the specified temperatures or pressures will result in a difference in how the machines work. Prolonged operation outside the standard limits is likely to result in early failure of the equipment.

Modern instrumentation and sensors are likely to have specific dates when they need to be recalibrated. Failure to check and recalibrate these devices may result in the system running outside of its normal design limits and therefore dangerous failures of breakdowns occurring.

Environmental protection

Make sure that in the event of a breakage or failure, NO fluid leak will be able to escape into the environment. It is always important, and in most countries, a legal requirement to protect the environment.

A common solution is to build a bund wall around the power unit or hydraulic system. Then if any connection or pipework leaks the complete reservoir volume can be retained with the bund wall.

Tank failures do happen but the most likely cause will be a slow leak or syphon point that occurs overnight or at a weekend when no one notices. If the fluid cannot be contained and a leak would be detrimental to the environment, then bio-degradable fluids should be considered.

Typical start-up procedure

Please note that this is NOT a 'first-time' start-up procedure which is likely to be far more comprehensive e.g. after maintenance or commissioning.

This procedure assumes that all of the above requirements have already been completed e.g. assessments, documentation, and training.

  • Visually inspect the equipment for damage, leaks, wear, or missing parts etc.
  • Make sure no maintenance work is ongoing. It is important to seek advice if repairs were required or completed since the last time the equipment was used.
  • Check support systems are available e.g. cooling water, electrical power or air etc.
  • Check the fluid level is in the normal start-up range with cylinders in the safe, shut-down condition.
  • Check the fluid temperature is within the normal range for start-up. Warm the fluid to the correct working temperature if possible and definitely if the ambient temperature gets too cold.
  • Check the handle positions are correct for all line isolating valves. Also check their security locks, if fitted.
  • Check the actuators or loads are clear to move.
  • Check instrument readings are within the normal start up ranges, particularly accumulator pre-charge pressures.
  • Check all guards are in place and there is no risk to anyone from flying hoses, fittings, or moving parts.
  • Press the start button(s) in the prescribed sequence. If there are any unusual noises or movements then press the stop button immediately and seek assistance.
  • Check that the gauges and instrumentation move to within the expected ranges.
  • Observe the filter clogging indicator movements as these are likely to show higher readings when the fluid is cold.
  • Gradually increase any speeds, feeds or pressures until the normal working conditions are met.
  • Check instrumentation readings are still within expected ranges.

This list only covers a simple installation and will not include all potential issues. Always check the specific start-up procedure for your equipment.

Typical operating procedure

While the equipment is running:

  • Always listen and watch for any noises or movements that may indicate the start of something failing or wearing out. Stop immediately if concerns are raised.
  • Constantly monitor the gauges and instrumentation for unusual reading, or readings that drift outside the normal working range.
  • Constantly monitor for leaks or fluid smears that may indicate a larger leak is about to start.
  • Look out for other personnel and stop them getting too close to working equipment or walk into areas that could be potentially unsafe.
  • Keep records of system operation e.g. how long sequences take, maximum and minimum temperatures relative to the ambient conditions, number of cycles, or on-load operating hours etc.

Typical shut-down procedures

Shut down procedures are not necessarily the reverse of start-up procedures and likely to include:

  • Wait for all operating or automated sequences to finish and the equipment to return to standby conditions.
  • Gradually low all speeds, feeds or pressures where possible.
  • Make sure all loads are returned to a safe where they cannot fall or creep and further.
  • Press the stop button(s) in the prescribed sequence.
  • Wait for the pressures to decay and the gauges or instrumentation to return to their zero or off conditions.
  • Open accumulator safety block drain down valves if pressure venting does not occur naturally.
  • Do not close any ball valves or isolators unless the shut-down procedure specifically advises you to.
  • Isolate the electrical supply.
  • Record all relevant operating details, times or abnormal operation in the relevant documents.
  • Leave warnings on the equipment and notify all relevant personnel if any abnormal operation has occurred.

Planned and preventative maintenance

All maintenance procedures and repairs should be recorded and the operator should have access to this information. It is important for the operator to know when work has been carried out on equipment so that they can implement appropriate precautions where required. For anyone operating a machine it is always good to know that the proper maintenance procedures are in place and that all work has been adequately recorded and reviewed.

Reporting and recording facilities

As part of the maintenance procedure it is important the machine operator reports and records all breakdowns, accidents or abnormal performance. This is the only way that support staff can be made aware of potential issues and can therefore carry out the appropriate actions.