This type of fluid contains about 95% water and 5% additives, such as emulsifiers, wetting agents, lubricity improvers, rust inhibitors, bactericides, defoamers and thickeners.
There are four types of HF-A fluids in normal use today. These are:
Oil Emulsions (soluble oils)
The concentrate, which contains mineral oil, emulsifiers, anti-corrosion
additives, biocides and EP-additives for protection against wear, are mixed with
water, forming a stable emulsion.
Micro-emulsions
As the protection against wear provided by oil soluble additives is
considered better than provided by water-soluble additives, concentrates have
been developed in which the proportion of oil necessary for the introduction of
the additives is relatively small.
This oil content is distributed throughout HFA fluids manufactured with such
concentrates in the form of sub-micron droplets, which is why these fluid are
generally known as micro-emulsions.
Synthetic Solutions
The concentrates are free from mineral oil and together with the
preparation water form a stable solution. These products typically incorporate
water soluble esters and glycols to provide lubricity and anti-wear properties.
As far as protection against corrosion is concerned, these fluids possess the
same properties as the emulsions.
RECENT DEVELOPMENTS
The factors influencing the development of high water content fluids have changed significantly from focusing on economic replacement to environmental acceptance and safety.
Historically, the earlier fluids that best addressed the market demands were the unthickened micro-emulsions. Micro-emulsions had superior anti-wear, corrosion resistance and stability compared with the conventional soluble oils and synthetics that were traditionally used. In addition, it was possible to formulate waste-treatable micro- emulsions that were acceptable, relative to established fluid disposal practices. Furthermore, systems could be formulated with little or no oil, which resulted in improved biostability in the "as used" dilution strength, and ready biodegradability when grossly diluted in waste treatment systems or accidental spills.
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Mineral
oil hydraulic system to high water based fluids change over procedure |
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Fire
Safe Fluid Guide The information contained under different section
headings in this guide is applicable in other sections. For example, the
information on Fluid Management under the Fire Resistant Hydraulic Fluid
section is applicable to all other sections. Likewise, the fire prevention guidelines under the
Heat Transfer Section is applicable in all other sections. |