How to Keep the Heat in Your Oven
Parameters to consider when choosing the insulation type, vapor barriers and cladding for each process heating application include:
- Hot face (process) temperature (maximum and normal operation).
- Average ambient cold-face temperature.
- Indoor or outdoor.
- Space considerations.
- Moisture and corrosion potential.
- Installation configurations.
- Thermal conductivity requirement.
- Wind factor.
- Removability requirement.
After the insulation type has been selected, thickness requirements must be determined. Except when there is a limited space requirement, the most economical insulation thickness should be used. This thickness will yield the best return on investment. Table 2 shows the insulation thickness used to calculate heat savings. Table 3 shows heat loss data from bare surface area on NPS piping and flat surfaces. Table 4 shows heat loss after an appropriate type and insulation thickness has been specified. For the most part, heated processes should be designed to have the insulation perform to a 95 percent or better efficiency level. Considering this, based on energy costing $5 per million BTU, table 5 shows the dollars per square foot that will be lost per year from bare, uninsulated metal surfaces. If the equipment is outdoors and exposed, it can get wet, and the energy dollar loss goes up even more.
Dry Run, TrainingAfter the insulation type and thickness have been determined, it is critical that the insulation remain dry whether the process is operating or not. If the insulation is allowed to get wet, it will lose about 90 percent of its insulation value. In addition, corrosion problems will begin once moisture enters your insulation system. Specifying and installing a good vapor or moisture barrier that is maintained properly will accomplish the job of keeping the heat in your oven.
For more information about NIA or NAIMA training class schedules or to purchase 3 E Plus software, call 703-683-6422 or visit www.insulation.org.