Glossary

A chemical added to a base fluid in order to improve specific properties of the lubricant such as fluid life, lubricity, wear protection, rust protection, etc.

Lowest temperature at which a fluid spontaneously ignites in normal atmosphere without an external source of ignition, such as a flame or spark.

This is a flash point test that is conducted in a vessel where the fluid is exposed to atmosphere. The temperature of the substance is gradually raised and an ignition source is passed over the top of it until the fluid reaches a point at which it “flashes” and ignites. 

A vessel designed to account for the expansion of heat transfer fluid as it is heated. It accommodates fluid expansion and helps to avoid overflow into the operating facility or over pressurization of system devices and associated equipment.

Lowest temperature at which vapors of the fluid will “flash” in the presence of an ignition source.

Accumulation of unwanted deposits on heat transfer surfaces. This creates an additional barrier for heat transport, reduces heat transfer efficiency and necessitates an increase in the temperature of the heat source. 

The heat capacity of a fluid is the amount of heat (usually expressed in calories, kilocalories, or joules) needed to raise the fluid's temperature by one degree (usually expressed in Celsius or Kelvin).

The initial boiling point at a given pressure is defined as the temperature value when the first bubble of vapor is formed from the liquid mixture. For a multicomponent liquid mixture like thermal fluids, there is no single boiling point to vaporize the complete mixture. The boiling for such mixtures occurs over a range of temperature which depends on the components involved, pressure of the system and also the affinity they have for each other.  

An examination of potential lubrication- and fluid-related food-contamination risks in a facility, generally conducted as part of an HACCP (hazard analysis and critical control point) plan.

This is the temperature at the conductive heat transfer boundary layer – pipe walls, heating elements. This is usually higher than the maximum bulk temperature.

This results from the formation of bubbles or cavities in areas of relatively low pressure around a pump impeller. The imploding or collapsing of these bubbles trigger intense shockwaves inside the pump, causing significant damage to the impeller and/or the pump housing. In contrast with synthetic fluids, mineral oil-based heat transfer fluids have low vapor pressures and a lower tendency for bubble formation.

A lubricant additive for protecting ferrous (iron and steel) components from rusting caused by water contamination or other harmful materials from oil degradation. Some rust inhibitors operate similarly to corrosion inhibitors by forming inert films on metal surfaces. Other rust inhibitors absorb water by incorporating it into a water-in-oil emulsion so that only oil touches the metal surfaces.

This is a fluid degradation phenomenon that occurs when a fluid is heated above its maximum bulk temperature. Consequently, the fluid’s viscosity, flash point, fire point and auto-ignition temperature reduce significantly.

Measure of fluid acidity and indication of fluid oxidation. It is determined by the amount of potassium hydroxide in milligrams that is needed to neutralize the acids in one gram of fluid.

Measure of a fluid’s resistance to flow. This is typically measured as the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid. Viscosity varies inversely with temperature. The lower the viscosity, the higher the heat transfer efficiency. The higher the viscosity, the better the thermal stability of a fluid.