In our profession, we’re all about the safety of hydraulic systems. One of the most frequently asked and important inquiries we receive is about the flammability of hydraulic fluid. This is a very relevant concern because, in some cases, hydraulic systems work under extreme pressure and temperatures, and in such situations, the possibility of fires is not merely hypothetical but very real. It is very important to be aware of such hazards in order to provide a safe working environment and protect your precious machinery.
Is hydraulic fluid flammable? The truth of the matter is not quite so straightforward as a simple yes or no. The degree to which this is a problem for you will depend entirely on which type of fluid you have in your hydraulic systems and under what conditions you operate. At Coastal Hydraulics, which is comprised of hydraulic experts and repair specialists, we have seen firsthand the damage which has resulted from failing to follow safety guidelines.
Understanding the Composition of Hydraulic Fluids
In order to be able to grasp the danger of fire and hydraulic fluid as a flammable component, we have to examine the composition of the fluid. The truth of the matter is that the majority of fluids used in hydraulics today are made of mineral oils. These fluids, because of their composition, have the same characteristics of burning as other fluids made of petroleum. These fluids contain hydrogen and carbon.
These oils are widely used due to their low cost and good lubricating and protecting properties. The composition of these oils gives them a natural flash point, which is the lowest temperature at which the vapors above the liquid would ignite if an ignition source is present. The liquid itself is not as explosive as gasoline, but the vapor is where the problem often originates.
Factors That Increase Flammability
In most cases, the risk of a fire from hydraulic fluid is not posed by a puddle of oil resting on the floor. The real risk occurs when the oil is under pressure. Hydraulic systems have a high level of pressure, which can be several thousand PSI. When a hose bursts or a seal breaks, oil can be released as a fine mist or spray.
This atomized spray is highly flammable because it easily mixes with the oxygen in the air. If this spray comes into contact with a hot surface such as the manifold of an engine, welding sparks, or melted metal, it will immediately catch fire. We always warn our clients that the temperature and pressure of the system are also essential in ensuring the safety of the system from fires.
Assessment of Various Fluids and Fire Resistance
However, not all types of hydraulic fluids pose similar risks. Various types of fire-resistant fluids have been developed to function in a safe manner in dangerous environments where ignition sources are present.
Water-glycol fluids are a common substitute. They have a large proportion of water, which resists combustion. They are very good at fire resistance, but we have found them to be sometimes inferior to mineral oils on lubrication, so compatibility has to be checked.
Another class of synthetic fluids that are ignition resistant is phosphate esters. These fluids are self-extinguishing; that is, they will not keep on burning once the ignition source is removed. They are extremely efficient from a safety point of view, although their cost can be high, and special hoses and seals are needed since they are harmful to regular rubber parts.
Polyol esters are a different alternative. Their flash point is higher than that of mineral oils, and if they do burn, there is less smoke generation. This is used in applications where safety and the environment are of concern.
Fire Risk Management for You
The flammability of hydraulic fluid is a problem which must be addressed. Petroleum-based fluids have been the norm and have worked well; however, they have always posed certain dangers, particularly when failures occur at high pressure. Selecting the appropriate fluid is not always easy.
We believe the best protection against hydraulic fluid flammability is maintenance. It’s the leaks which start fires. By making certain your hoses, seals, and connections are checked on a regular basis and replaced before a failure occurs, you will go a long way in preventing the creation of the potentially deadly atomized mist. If you are concerned about the safety of your current hydraulic system or would like guidance on a changeover to fire-resistant fluids, contact us at Coastal Hydraulics for a hydraulic repair service.