Machine Safety in Hydraulic Systems

Hydraulic systems are the preferred choice for generating large, directed forces. Whether for a hydraulic press, lifting platform, or excavator boom, hydraulics offers simple, flexible, and quickly implementable solutions for every challenge.

However, hydraulic systems also pose dangers that must be considered during their operation. To enhance machine safety in hydraulic systems and keep them as safe as possible for the operator, numerous standards and laws have been developed.

What Dangers Do Hydraulic Systems Pose?

A hydraulic system does not appear particularly threatening. The work processes are barely visible from the outside, and movements appear relatively slow. Evading approaching actuators always seems possible. However, this is only true as long as the system operates within desired limits. Malfunctions in hydraulic systems can have the following consequences:

• spurting hot hydraulic fluid
• bursting housings
• whipping hoses
• fire hazard due to overheating
• sudden lowering of actuators due to pressure loss

When is Machine Safety in Hydraulic Systems Compromised?

If a leak occurs in a hydraulic system, the working fluid escapes. Depending on the operating pressure, temperature, and size of the leak, the fluid jet can pose a high risk of injury and scalding.

Excessive pressure can cause not only lines and hoses to burst, but also the housings of pumps, valves, or even tanks.

Tearing, unsecured hoses, while simultaneously spurting hydraulic oil, whip uncontrollably in all directions – an extremely dangerous situation.

Inadequate heat dissipation can lead to heat buildup, which in turn can trigger a fire or an explosion.

Pressure loss in an excavator arm or a lifting platform, without safety measures, leads to the immediate collapse of the often multi-ton weight. This poses an extreme danger to life for all bystanders.

How Machine Safety in Hydraulic Systems Can Be Ensured:

Hydraulic systems are subject to the Machinery Directive. This standard forms the basis for occupational safety law. Operators and manufacturers of hydraulic systems are therefore obliged to implement constructive measures that make the machines as safe as possible.
As in mechanical engineering, the “three-step safety concept” underlies the safe design of hydraulic systems. Simply put, it states the following:

1. Design the machine to be as safe as possible.
2. Mitigate what cannot be made structurally safe through constructive measures.
3. Document what cannot be mitigated with warning signs.

A safe design for a hydraulic system is given, for example, when all components can withstand the expected peak pressure multiple times over. Creeping cracks and sudden bursting of housings are practically ruled out with this over-dimensioning.

Constructive measures include, for example, housings or hose burst protection. Warning signs, which, for instance, warn of hot spots or prescribe protective equipment, are only the “last resort.”

Further information on the safe design of hydraulic systems can be found, for example, in the Pressure Equipment Directive or DIN EN ISO 4413:2011-04 “Fluid power systems – General rules and safety requirements for hydraulic systems and their components.”