CHARACTERISTICS - MINERAL THERMIC FLUID

VISCOSITY:

Resistance to flow About 32-36 cSt at 40 C.

High viscosity:-

• Loads pump motor, especially during cold start
• Pump motor sized for cold starting
• Also, poor heat transfer 

Useful when:-

• Selecting thermic fluid for low ambient temperatures
• Checking condition – Oxidation increases viscosity

SPECIFIC GRAVITY:

• Normally around 0.9 at ambient temperature.
• Reduces with increase in temperature – approx. 0.7 at 300 C.

This means-

For TF :1 bar = 14 MLC (Meter of Liquid Column)

SPECIFIC HEAT:

Quantity of heat required to heat unit mass through unit temp. difference, at a given temperature

About 0.45 at 30 C., 0.7 at 300 C.

Unit : Kcal/Kg C

This can be used when:

• Relating thermic fluid flow and delta T
• Estimating heat transferred in process

FLASH POINT:

• Minimum temperature of fluid at which vapors just above surface of fluid ignite with a flash when shown a naked flame or a spark. The flame is not sustained, since the vapors are not replaced fast enough from fluid surface.
• It is measured using a standard size cup.
• This indicates ignitability of vapors formed during heating of oil & presence of easily ignitable constituents of oil.
• Flash Point of fresh oil – 200 - 215 Deg C.
• Flash point of a thermic fluid held at high temperature keeps falling.

FIRE POINT:

• Minimum temperature of fluid at which vapors just above surface of fluid ignite when shown a naked flame or a spark and the flame is sustained since vapors are replaced fast enough from fluid surface.
• It indicates that fluid has cracked more and is generating more vapors than at Flash Point.

BOILING POINT:

Temp. at which change of phase takes place.

Boiling point varies from 330 to 371Deg C, depending on the brand.