23
General Operation
Bath Fluid
Fluid Lifetime
8.3.7
Many fluids degrade over time because of evaporation, water absorption, gel ling,
or chemical breakdown. Often the degradation becomes significant near the upper
temperature limit of the fluid, substantially reducing the fluid’s lifetime.
8.3.8 Safety
When choosing a fluid always consider the safety issues associated. Obviously
where there are conditions of extreme hot or cold there can be danger to people and
equipment. Fluids may also be hazardous for other reasons. Some fluids may be
considered toxic. Contact with eyes, skin, or inhalation of vapors may cause injury. A
proper fume hood must be used if hazardous or bothersome va pors are produced.
Warning: Fluids at high temperatures may pose danger from BURNS, FIRE,
and TOXIC FUMES. Use appropriate caution and safety equip ment.
Fluids may be flammable and require special fire safety equipment and proce dures.
An important characteristic of the fluid to consider is the flash point. The flash point
is the temperature at which there is sufficient vapor given off so that when there is
sufficient oxygen present and a ignition source is applied the va por will ignite. This
does not necessarily mean that fire will be sustained at the flash point. The flash point
may be either of the open cup or closed cup type. Either condition may occur in a bath
situation. The closed cup temperature is always the lower of the two. The closed cup
represents the contained vapors in side the tank and the open cup represents the vapors
escaping the tank. Oxygen and an ignition source will be less available inside the tank.
Environmentally hazardous fluids require special disposal according to applica ble
federal or local laws after use.
Cost
8.3.9
Cost of bath fluids may vary greatly, from cents per gallon for water to hun dreds of
dollars per gallon for synthetic oils. Cost may be an important consid eration when
choosing a fluid.
Commonly Used Fluids
8.3.10
Below is a description of some of the more commonly used fluids and their
characteristics.
