"There's Not Much to this Designing an Insulation System; Right?!"

When designing thermal insulation for a refrigeration system, consideration should be given to both thermal process and mechanical design factors.

Thermal design factors include desired heat gain or heat loss, prevention of condensation, ambient temperature, wind velocity affecting heat gain or loss, insulation economics and thermal properties of insulation materials. That the products are suitable for the application.

Mechanical design factors include geographical location, environmental corrosivity and wind velocity affecting mechanical strength of the thermal insulation system. Other design factors include consideration for specific processes which require special considerations during the selection of insulation materials.

Geographical design considerations depend on the facilities location. Plants located in hot and humid climates will have different parameters than a plant located in a dry cooler climate.

Process control considerations - Since cold process BTU's are more expensive than hot process BTU's; the amount of heat gained by a cold process must be kept to a minimum. The typical rule of thumb is to provide sufficient insulation to maintain an 8-10 BTU/HR/SF heat gain to cold process. The design ambient temperature and wind conditions must also be included into consideration.

In hot, humid environments, it is virtually impossible to prevent condensation 100% of the time. Uneconomical insulation thickness would be required to achieve this. Outdoors, normally the 8-10 BTU/HR/SF heat gain is adequate to stop condensation the majority of the time. Specific calculations for indoor requirements may be obtained from the manufacturer.

It is essential that the ambient temperatures to be used for insulation design should be agreed upon between the purchaser and designer. Normally, these temperatures are based on yearly average winter and summer conditions. However, in critical process design, such as required for refrigeration, we recommend that the engineer choose the worst case scenario instead of an average temperature.

Wind velocity considerations - has a direct impact on mechanical and thermal design of insulation. Wind changes the resistance of the air side film coefficient. It accelerates heat loss or gain and lowers surface temperature in above ambient applications and raises temperature in below ambient applications. In below ambient applications wind may raise the surface temperature above the dew point and condensation will decrease. This normally allows lesser thickness of insulation for the same service when compared to surface temperature without the effect of wind.

However, it should be noted that a difference in Emissivity Factors used will result in different thickness required. If we assumed for In Service Indoor, say 0.9 Emittance for PVC as compared with 0.1 Emittance for Aluminum, Oxidized, In

Service, Outdoors, it may raise the insulation thickness required to greater for indoors than outdoors.

Relative Humidity of atmosphere plays an important role. High atmospheric humidity can cause excessive condensation, and accelerate galvanic corrosion of unprotected steel. For most below ambient design conditions, condensation control is the criteria for determining the insulation thickness. A different criteria would be to maintain a specific operating temperature for process control (as mentioned above).

The insulation system would be designed so that the surface temperature of the insulation system is above the dew point of the ambient air. This will keep the condensation from forming on the surface of the insulation and therefore avoid product contamination, safety hazards and building damage from dripping condensate.

The ambient conditions of relative humidity and temperature, along with the process temperature, determine the required thickness of insulation. It is again essential to agree with the purchaser on what percentage (%) relative humidity is acceptable. Normally the worst case scenario, rather than an average should be selected for design applications.

EXTOL INSULATION SYSTEMS: COMPLETE PRODUCT LINE    COMPOSITE INSULATIONS    CONTOURED HEAD SYSTEMS    EXCEL-LAP SYSTEMS    ISOWRAP® PRECISION CUT    TRACED LINE SYSTEMS    VALVE & JACKET SYSTEMS

DATA SECTIONS: DESIGN & INSTALLATION TIPS ESTIMATING TIPS / & CHARTS EXTOL SYSTEMS DATA MSDS LISTED BY MANUFACTURER MSDS LISTED BY PRODUCT TYPE PRODUCT DATA SHEETS PUBLICATIONS & ARTICLES HELPFUL SALES/TRAVEL INFO WBE CERTIFICATIONS

BACK TO MAIN OBTAIN A QUOTE SURPLUS MATERIAL PLACE AN ORDER EMPLOYMENT OPPORTUNITIES PASSKEY SECTION: WAIVER / PASSKEY REQUEST INSULATION SPECIFICATIONS DETAILED DRAWINGS_COLD/HOT