Cabinet Cooler Systems® - Information Sheet
Selecting the Right Cabinet Cooler System
With or Without Thermostat Control
EXAIR Cabinet Coolers are available with or without thermostat control. The continuous coolers (Model 4200 and 4700 series) are recommended when constant cooling and a constant positive purge are desirable. The thermostatically controlled systems (Model 4300 and 4800 series) save air by activating the cooler only when internal temperatures approach critical levels. The adjustable thermostat is factory set at 95°F (35°C). Thermostatic systems are recommended where heat load fluctuates and continual purge is not required.
All EXAIR Cabinet Cooler Systems contain a 5 micron Automatic Drain Filter for the compressed air supply and a Cold Air Distribution Kit to circulate the cold air throughout the enclosure.
Environmental Considerations
NEMA 12 (IP54) Cabinet Coolers (dust-tight, oil-tight) are ideal for general industrial environments where no liquids or corrosives are present.
NEMA 4 (IP66) Cabinet Coolers (dust-tight, oil-tight, splash resistant, indoor/outdoor service) incorporate a low pressure relief valve for both the vortex tube and cabinet air exhaust. This valve closes and seals when the cooler is not operating, to maintain the integrity of a NEMA 4 enclosure.
NEMA 4X (IP66) Cabinet Coolers (corrosion resistant) offer the same protection as NEMA 4, but are constructed of 304 stainless steel for food service, pharmaceutical and corrosive environments.
How to Calculate Heat Load for Your Enclosure
To determine the correct model for your application, it is first necessary to determine the total heat load to which the control panel is subjected. This total heat load is the combination of two factors — heat dissipated within the enclosure and heat transfer from outside into the enclosure.
To Calculate Btu/hr.:
1. First, determine the approximate Watts of heat generated within the enclosure. Watts x 3.41 = Btu/hr.
2. Then, calculate outside heat transfer as follows:
a. Determine the area in square feet exposed to the air, ignoring the top of the cabinet.
b. Determine the temperature differential between maximum surrounding temperature and desired internal temperature. Then, using the Temperature Conversion Table (below), determine the Btu/hr./ft.2 for that differential. Multiplying the cabinet surface area times Btu/hr./ft.2 provides external heat transfer in Btu/hr.
3. Add internal and external heat loads for total heat load.
Temperature Conversion Table |
|
| Temperature Differential °F | Btu/hr/ft.2 |
| 5 | 1.5 |
| 10 | 3.3 |
| 15 | 5.1 |
| 20 | 7.1 |
| 25 | 9.1 |
| 30 | 11.3 |
| 35 | 13.8 |
| 40 | 16.2 |
Example:Internal heat dissipation: 471 Watts or 1,606 Btu/hr. Cabinet area: 40 ft.2 Maximum outside temperature: 110°F Desired internal temperature: 95°F The conversion table (above) shows that a 15°F temperature differential inputs 5.1 Btu/hr./ft.2 40 ft.2 x 5.1 Btu/hr./ft.2 = 204 Btu/hr. external heat load. Therefore, 204 Btu/hr. external heat load plus 1,606 Btu/hr. internal heat load = 1,810 Btu/hr. total heat load or Btu/hr. refrigeration required to maintain desired temperature. In this example, the correct choice is a 2,000 Btu/hr. Cabinet Cooler System. Choose a Cabinet Cooler model by determining the NEMA rating of the enclosure (type of environment), and with or without thermostat control. |
To Calculate Kcal/hr.:
1. First, determine the approximate Watts of heat generated within the enclosure. Watts x .86 = Kcal/hr.
2. Then, calculate outside heat transfer as follows:
a. Determine the area in square meters exposed to the air, ignoring the top of the cabinet.
b. Determine the temperature differential between maximum surrounding temperature and desired internal temperature. Then, using the Metric Temperature Conversion Table (below), determine the Kcal/hr./m2 for that differential. Multiplying the cabinet surface area times Kcal/hr./m2 provides external heat transfer in Kcal/hr.
3. Add internal and external heat loads for total heat load.
Temperature Conversion Table (METRIC) |
|
| Temperature Differential ° C | Kcal/hr/m2 |
| 3 | 4.5 |
| 6 | 9.7 |
| 9 | 15.1 |
| 12 | 21.0 |
| 15 | 27.0 |
| 18 | 34.0 |
| 21 | 41.0 |
Example:Internal heat dissipation: 471 Watts or 405 Kcal/hr. Cabinet area: 3.7m2 Maximum outside temperature: 44°C Desired internal temperature: 35°C The conversion table (above) shows that a 9°C temperature differential inputs 15.1 Kcal/hr./m2. 3.7m2 x 15.1 Kcal/hr./m2 =56 Kcal/hr. external heat load. Therefore, 56 Kcal/hr. external heat load plus 405 Kcal/hr. internal heat load = 461 Kcal/hr. total heat load or Kcal/hr. refrigeration required to maintain desired temperature. In this example, the correct choice is a 504 Kcal/hr. Cabinet Cooler System. Choose a Cabinet Cooler model by determining the NEMA rating of the enclosure (type of environment), and with or without thermostat control. |
Cabinet Cooler Sizing Guide
Need help in determining the right Cabinet Cooler for you? Let us help! Fill our our Cabinet Cooler Sizing Guide to submit information online about your control panel cooling problem. or download the PDF version, complete it offline and fax it to us at (513) 671-3363.
For immediate help, call our Application Engineering Department at 1-800-903-9247.