Is Hydraulic Fluid Flammable? You May Be Surprised

Hydraulic fluid can be found virtually anywhere that small or large equipment is used. Homes, manufacturing or industrial businesses, and cars (brake fluid or power steering fluid) are examples. In hydraulics operations, fluids are a must. And the life expectancy of hydraulics relies on the effectiveness and quality of the fluid used.

Surrounding conditions, such as temperature changes, impact hydraulic fluids and the operation of hydraulics. But is hydraulic fluid flammable?

It depends. Hydraulic fluid can be flammable and poses a fire risk when a hydraulic system fails, and there's an ignition. Petroleum-based fluid, like mineral oil, can ignite at temperatures between 300-600 degrees Fahrenheit, technically making it combustible. Whereas water-based fluids are non-flammable. 

Is Hydraulic Fluid Flammable

What Is Hydraulic Fluid?

Hydraulic fluid is the carrier of energy transfer within a hydraulic system. The fluid acts as power transmission, meaning that without it, the hydraulic system experiences damage and failure, and the life span is hugely short-lived.

Additionally, hydraulic oils act as a sealant and lubricant and offer corrosion protection. They also prevent oxidation damage and are a contaminants eliminator. All these functions increase effectiveness, performance, and durability.

What does it contain? The ingredients vary depending on the fluid type but can contain phosphate ester, mineral oil, water glycol, water/oil emulsions, water, or other fire-resistant fluids - it all depends on the intended application within the hydraulic system. Water-based fluids are less hazardous and fire-resistant.

Can You Mix Hydraulic Fluids?

Each type of hydraulic fluid varies in additive contents, and the easiest way of messing up hydraulic performance is by mixing the fluids. The chemical reaction of the ingredients could cause component damage, elevated mechanical wear, and breakdown.

If a dire situation arises, fluids with similar viscosity can save the day but flush the fluid immediately after use and change to a new one.

Do Hydraulic Oil And Hydraulic Fluid Mean The Same Thing?

The intended use determines that. For example, hydraulic fluids are common in automobile systems, such as automatic transmissions, brake systems, and power steering units. However, hydraulic oil can't be used for this purpose and is used in a more industrial capacity.

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Is Hydraulic Fluid Flammable?

The answer to this question depends upon the ingredients that make up the fluid. Any water-based fluid will most definitely not be flammable. Petroleum based fluids pose a different risk, but that risk requires very high temperatures to impact flammability. 

They can ignite between 300-600 degrees Fahrenheit and spontaneously combust when temperatures reach 500-750 degrees Fahrenheit. So normal usage shouldn't pose any significant risk, but since ignition can occur, it's always prudent to keep hydraulic oils away from any open flame or spark and store unused fluid safely.

What Do I Do To Extinguish A Hydraulic Fire?

Extinguishing any fire requires a prompt response in the right way, as it can cause a massive hazard to property and even lives if left unchecked. In addition, there's a fire risk when a system failure exists and fluid leaks from any ruptured parts.

Petroleum based hydraulic fluid poses a higher risk of combustion. The oil may ignite easily when in contact with open flames or hot surfaces, increasing its flammability. This mainly occurs because the oil's pressure can change its characteristics, increasing the possibility of a hydraulic oil fire. An instant system shutdown can help shut off the fluid motion and extinguish the fire.

Other Fire Prevention Steps Include:

  • Ensure you're operating the hydraulic system far from any sources of ignition. Also, opt for fire resistant hydraulic fluid if using in areas where it's hard to eliminate potential ignition sources. If you choose synthetic fluids, do your research to ensure a recognized testing lab approves the fluid.
  • Make sure the hydraulic system is suitable for the applied pressure and that there is adequate protection from vibration and damage. Excessive shaking causes hydraulic line leakage, and only the appropriate piping hose can help.
  • Regular system maintenance and inspection are crucial as a skilled inspector will quickly identify leaks and restore all other breakdowns in the hydraulic system. In addition, regular servicing aids in the resolution of critical problems such as fires and assists in the assessment of equipment and crucial components such as joints and hoses.
  • Maintain a clean, fluid-free environment around all hydraulically operated machines to minimize material contamination. 
  • Ensure the emergency exits are easily situated and adequate if a flash fire occurs for employees and other people to escape. In addition, the fire alarm system should be reliable in a central unit, and there must be proper evacuation protocols for fire outbreak events.

Does Temperature Affect Hydraulic Fluid?

Yes, temperature variations affect the hydraulics and the fluid. For example, low temperatures create high viscosity, meaning that the fluid thickens and fails to circulate evenly. This may cause system damage as there will be starved pipes, non-lubrication, and rupture of critical parts.

An increased temperature reduces fluid viscosity (thin fluid) and leads to oxidation.

Operating a system when fluid is thin for extended periods compromises the equipment and the fluid. This will jeopardize performance. 

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What Types Of Hydraulic Fluids Are There?

Petroleum based fluids are common in hydraulics, and the additives make the fluid a great lube. But hydraulic fluids are further categorized into:      

  • Water based hydraulic fluid     
  • Petroleum based hydraulic fluid
  • Synthetic hydraulic fluid

Water Based Fluids: This common type is a mixture of water and oil, making the fluid fire-resistant. Water glycols and water/oil emulsions are two types of water based fluids. The fluids are fire-resistant and have a practical cooling effect, but the corrosion rate is high.

Petroleum Based Fluids: Petroleum based fluids contain additives that minimize foaming, improve lubrication, and prevent corrosion, making the fluid common in hydraulic systems. But the oil is flammable in high temperatures and high-pressure leaks.

Synthetic Fluids: These laboratory-made hydraulic fluids offer good fluid lubrication and stability. They have zero volatile materials and water content. So, the fluids function flawlessly in high temperatures and high pressure without losing any crucial components.

What are the Properties Of An Effective Hydraulic Fluid?

Hydraulic oil is crucial for hydraulics, and it makes sense to use a quality product. But how do I know what properties make a hydraulic fluid good?

Below are what to look for when choosing the best hydraulic oil.

  • Viscosity: A fluid with sufficient viscosity provides excellent sealing and lube. When the viscosity is low, there is a lot of damage; hydraulics are less efficient when it is too high.
  • Viscosity Index: Temperature changes affect fluid viscosity, and the viscosity index helps to indicate the variations. High-index fluids deliver flawless results.
  • Compressibility: Exposing fluid to increased pressures relies on its compressibility performance. High compressibility leads to reduced efficiency and greater apparent viscosity.
  • Wear Resistance: This helps indicate the fluid's capacity to reduce abrasive wear in friction parts. Hydraulic oils containing anti-wear additives are perfect and efficient.
  • Demulsibility: Demulsibility is important for emulsion resistance but also aids in filtration and removal.
  • Oxidation Stability: Oxidation drastically reduces fluid life, leaves crud and varnish behind, and wreaks havoc on hydraulics. Choose a fluid that can sustain heat and resist oxidation to prevent this.

Final Thoughts

Hydraulic fluids are essential for operating hydraulic systems as they act as energy transfer channels. But is a hydraulic fluid flammable? As explained above, it depends on the ingredients.

For instance, petroleum based hydraulic fluids are combustible, while water-based are less hazardous. However, flammability increases due to high pressure and any leaks of fluids from the hydraulic systems, posing a fire hazard, so precautions and safety measures are essential. Lastly, choosing quality fluids goes a long way in extending the lifespan of the hydraulics and its efficiency.