While heating elements do not have a projected service life in most applications, the possibility of ultimate failure should be considered.
Provisions should be made for ready replacement if the potential downtime will be expensive or critical to production or other operations. Replacement parts should be stocked as necessary so that a failed element can be replaced in a short period of time without completely stopping or disrupting the process.
With that in mind:
- Keep the equipment clean, particularly
around the terminals, wiring enclosure and heater itself through a regular
maintenance program. In highly contaminating environments or in hazardous
atmospheric conditions, special attention should be directed to the terminal
boxes and electrical enclosures. Heater terminal enclosures can be designed
with special fittings to use positive inert gas pressure to prevent the
entrance of contaminants or explosive gases. Purging is a low cost solution to
many terminal problems where local codes permit the use of continuous purging.
- Use field wiring suitable for the temperatures
involved. Heater terminal boxes and enclosures usually get quite warm during
operation and may require special wiring techniques. For field terminal
connections inside the heater enclosure, alloy wire with high temperature
insulation is recommended unless the instruction sheet specifically states that
copper or low temperature insulated wire may be used. Never use rubber, wax-impregnated
or thermoplastic-insulated wire on high temperature heater applications because
these materials will deteriorate quickly with heat. Some insulating materials
may give off fumes that could cause injury or damage to the heating equipment.
Always check local electrical codes for proper wiring requirements.
- Use thermal insulation wherever possible to reduce heat losses. Insulation is relatively inexpensive and will pay for itself in a short time by reducing heat losses and operating costs. It also is desirable from the standpoint of personnel comfort and safety.