User manual

23
General Operation
Bath Fluid
Fluid Lifetime8.2.7
Many uids degrade over time because of evaporation, water absorption, gel ling,
or chemical breakdown. Often the degradation becomes signicant near the upper
temperature limit of the uid, substantially reducing the uid’s lifetime.
8.2.8 Safety
When choosing a uid 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 uids 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 ammable and require special re safety equipment and proce dures.
An important characteristic of the uid to consider is the ash point. The ash point
is the temperature at which there is sufcient vapor given off so that when there is
sufcient oxygen present and a ignition source is applied the va por will ignite. This
does not necessarily mean that re will be sustained at the ash point. The ash 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 uids require special disposal according to applica ble
federal or local laws after use.
Cost8.2.9
Cost of bath uids 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 uid.
Commonly Used Fluids8.2.10
Below is a description of some of the more commonly used uids and their
characteristics.