Hydraulic systems are one of the most versatile means of controlling motion and transmitting power.
These systems operate on the following basic principles:
- A hydraulic pump is used to create the flow of an incompressible fluid.
- Pressure can then be generated on a surface by restricting the flow of a fluid.
- If actuators (such as hydraulic cylinders) are placed in the flow of fluid, pressure will be exerted on the piston of the cylinder, resulting in a mechanical movement of the piston.
- As a result, this mechanical movement allows for the lifting, lowering, expansion or retraction of heavy loads, with greater control and force.
Due the nature of stored fluid under high pressure and the high force at work in hydraulic systems, it is extremely important to take care and observe appropriate safety practises. This information is a general guide to working safely with hydraulic tools and equipment, however it is important to recognise that many hydraulic systems are custom built for specific requirements, so individual safety requirements will vary.
Before working on any hydraulic system, ALWAYS assess the task you are going to do for potential hazards and danger. This is especially important if attempting a task for the first time or if you are unfamiliar with the circuit or system/equipment. If you are unsure, seek training from competent and experienced professionals before working with any hydraulic system.
HYDRAULIC ENERGY IS CAPABLE OF CAUSING SERIOUS INJURY OR DEATH
A pin sized hole in a hydraulic line, operating at 13.7 MPa (2000 psi), will create an oil exit velocity of approximately 1500 kilometres per hour. This can easily penetrate the skin and cause significant injury by what is known as a hydraulic fluid injection. This can be a life-threatening injury and requires emergency medical treatment.
As hydraulic systems may often operate at high temperatures, the fluid contained in these systems can often approach boiling point and may cause painful burns if they come into contact with the body. This can be a life-threatening injury and requires emergency medical treatment.
To minimise the risk of injury from working with hydraulic systems:
- ALWAYS conduct a thorough safety risk assessment of all requirements to perform work on hydraulic systems safely.
- ALWAYS use but understand the limitations of personal protective equipment including protective footwear, safety eyeglasses, gloves and protective clothing. REMEMBER that personal protective equipment may not protect against hydraulic fluid injection or oil burns, as high pressure and hot fluids may penetrate most gloves.
- ENSURE that you have a diagram of the system or circuit and understand it, to identify all the isolation points in the system and any stored energy such as accumulators or load locks on actuators that need to be dissipated.
- NEVER work on a live hydraulic system or a system under load.
- NEVER use part of the hydraulic circuit for any task for which it was not intended.
- NEVER manually feel for leaks.
- IDENTIFY and isolate all energy sources, using isolation devices which are preferably lockable. Hydraulic systems are often powered by and energy sources such as electricity or diesel and these power sources must be isolated and secured.
- ALWAYS use appropriate hydraulic fittings that are specifically designed for the intended purpose.
- ALWAYS check that the hose type and ends are adequately rated for the operating pressures in the system.
- DO NOT exceed the rating for hydraulic cylinders as this can place strain on the cylinder componentry and may prevent safe and effective operation.
Hydraulic systems may be fitted with an accumulator, which is a specially designed pressure vessel and is one of the most potentially dangerous components in the system. The accumulator can maintain system pressure in the event of system power loss or can be used to absorb pressure surges caused by sudden stopping or reversing of flow. The accumulator must be isolated from the circuit or completely discharged before attempting to disconnect any hydraulic component. As a specific procedure is usually required for each hydraulic system, it is important to know exactly how to perform this task. If at all unsure, do not attempt to proceed with the work.
- NEVER try to disassemble an accumulator without FIRST releasing pressure. If the accumulator is removed from the system without depressurising, fluid can be discharged at an uncontrolled rate, and this may cause the accumulator to projectile launch into the nearest people or objects in its path – with potentially fatal consequences.
Hydraulic systems often have load lock valves fitted, to lock raised loads into place when the system is paused. ALWAYS remember that raised loads are subject to gravitational forces and ALWAYS use mechanical stops when working near raised equipment, in case of lock, valve or other component failure. – NEVER walk under a load that is supported only by hydraulic components.
Hydraulic powered tools can be one of the safest methods of applying force to your work when the appropriate equipment is used correctly.
When operating hydraulic power tools:
- ALWAYS wear appropriate personal protective equipment.
- Do NOT exceed the rated pressure or force capacity of the equipment.
- NEVER use equipment with hoses that are kinked or bent.
- ALWAYS ensure that tools are well maintained and regularly serviced before use.
When used safely and in the manner for which they are designed, hydraulic systems and tools are a valuable and effective means of utilising hydraulic force to lift, pull, extend, tighten, open close and more. ALWAYS take care to observe safe working practises when handling hydraulic equipment and if unsure about any aspect of the work, ALWAYS consult a trained professional.