Understanding Hydraulic Oil Density


Insights from Sciencing

Published
<h3>Understanding Hydraulic Oil Density</h3> <br /><h4>Insights from Sciencing</h4>

Hydraulic oil, or hydraulic fluid, is available in many varieties with differing chemistries. Their densities range from 0.8 grams per milliliter (g/ml) up to about 1.0 g/ml.

Density

The density of a material is the ratio of its mass to the volume of space it occupies. In chemistry and physics, it is usually expressed as grams per milliliter (g/ml). In some fields it may be expressed as pounds per gallon.



Types of Hydraulic Fluid

Most hydraulic fluids fall into one of three broad categories: mineral oils, polyalkylene glycols (PAGs), or polyalphaolefins (PAOs).

Mineral Oils

The base stocks for mineral-oil-based fluids are manufactured from petroleum. Mineral oils are therefore hydrocarbons (they contain only carbon and hydrogen). Examples include most tractor fluids and many automotive transmission fluids. These fluids typically exhibit densities on the order of 0.8 to 0.9 g/ml and will float on water.

Polyalkylene Glycols

PAGs are synthetic fluids (not made from petroleum). They are commonly used as automotive brake fluids and as lubricants for air-conditioner compressors. Their densities are typically around 1.0 g/ml.

Polyalphaolefins

PAOs are synthetic hydrocarbons that are chemically very similar to mineral oils, but with better lubricating properties at very low and very high temperatures. Like mineral-oil-based fluids, they have a density of 0.8 to 0.9 g/ml.



Dave Pennells

By Dave Pennells

Dave Pennells, MS, has contributed his expertise as a career consultant and training specialist across various fields for over 15 years. At City University of Seattle, he offers personal career counseling and conducts workshops focused on practical job search techniques, resume creation, and interview skills. With a Master of Science in Counseling, Pennells specializes in career consulting, conducting career assessments, guiding career transitions, and providing outplacement services. Her professional experience spans multiple sectors, including banking, retail, airlines, non-profit organizations, and the aerospace industry. Additionally, since 2001, he has been actively involved with the Career Development Association of Australia.