Flame-resistant hydraulic fluids and their role in industry

The fire-resistant hydraulic fluids are not a common topic of everyday talks. However, they are present in our lives more often than we think. Let's think for a while where such fluids can be applied and what are their properties.

Published: 19-03-2020

Application of hydraulic systems increases in various industries, including machine engineering, metallurgy, automotive and many others. Various types of hydraulic fluids are used to ensure durability, reliability and proper operation of systems. In modern systems, these fluids have many applications, including:

  • transmission of energy and control signals,
  • heat dissipation,
  • lubrication of moving components,
  • sealing the system.

The first known hydraulic fluid was water, but currently it is not used in many systems and it is always enriched with e.g. anti-corrosion agents. Unfortunately, water used as the hydraulic fluid had many negative features: it caused corrosion, had insufficient viscosity, had no lubricating properties etc. This was the main reason for developing new solutions. Currently produced hydraulic fluids include:

  • polyol esters based oils,
  • PAO-based synthetic oils,
  • refined mineral oils,
  • polyglycol-based synthetic oils,
  • vegetable oils.

Particularly noteworthy are flame resistant hydraulic fluids used in the equipment and machines that operate in extreme conditions. They are usually used in applications with a high risk of ignition of hydraulic fluid as a result of contact with an open flame or electric spark. The use of flame-resistant hydraulic fluids eliminates the risk of fire hazard.

Flame-resistant hydraulic fluids have been classified in ISO 6743-4:1999 standard, which in Poland is known as PN-EN ISO 6743-4:2003 Lubricants, industrial oils and related products (class L). Classification. Part 4: H Group (Hydraulic systems). This group distinguishes 6 categories of such liquid (Table 1 is based on this standard).

Tab. 1 Division of flame resistant hydraulic fluids.

Offered products

PCC Group website offers three ready-to-use formulations of hydraulic fluids. The first two are Polikon TEST and Polikon TEST 50. These are flame-resistant hydraulic fluids of HFC type. They are mixtures of glycols, surfactants, functional additives, pigments and water. Glycols provide good low-temperature properties. They are designed for testing, maintenance and transport of hydraulic equipment. They are also used in the mining and machine industry. Their properties include excellent lubrication and low pour point. In addition, they are non-combustible, contain anti-corrosion and anti-foam additives. They are also mild for seals and very well soluble in water. Polikon TEST may be used at temperatures reaching -35°C. Polikon TEST 50 is unique in its ability to be uses at temperatures reaching -50°C.

The PCC offer includes also Roksol HSG. It is based on natural oil, glycols, surfactants, polymers, water and a set of enriching additives. It is used in the coking industry, mining, metallurgy and steel industry. This flame-retardant hydraulic fluid is readily soluble in lower aliphatic alcohols and water. Its pour point is at the level of -15°C. With its lubricating properties, the product is suitable as a flame resistant oil in the metallurgical industry. It may be also used in hydraulic systems of machines that work in particularly difficult conditions (e.g. in mining industry).

PCC Group offers also base oils, which are used by producers of fire resistant hydraulic fluids. Rokolub FR series includes fully synthetic oils that base on aryl phosphate esters. According to ISO 6743-4, the flame resistant hydraulic fluids of Rokolub FR series are classified as HFDR and meet the requirements of the following viscosity grades (ISO VG): 32, 46, 68. Products of Rokolub FR series have exceptional fire resistance, making them suitable for use in areas with a fire risk. Their unique self-extinguishing properties and exceptional fire resistance increase fire safety in terms of exposing liquids to contact with fire. Products in this range are effectively used as flame retardant liquids in industrial hydraulic systems, turbines and compressors.  Additionally, Rokolub FR T-46 ultra is used to develop specialized flame resistant oils for electro-hydraulic control systems used in the power industry, and for turbine oils that lubricate machine components in power plants.

This is only a brief introduction to a very large issue. However, we have to be aware of the substantial role played by hydraulic fluids, and how important is the selection of proper products to ensure safe and efficient operation.

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