2.2.2 Sensor (Air/Water-Cooled Housing)
The Air/Water-Cooled Housing option allows the sensor to be used in ambient tem-
peratures up to 120°C (250°F) for air-cooled, and 175°C (350°F) for water-cooled. It is
supplied with two 3.2 mm (1/8”) NPT brass fittings. Air flow should be 0.1 to 1.5
cmm (3 to 5 cfm). Water flow should be approximately 2 liters (0.5 gallons) per
minute, and water temperature should be 10 to 27°C (50 to 80°F) for efficient cooling.
Chilled water below 10°C (50°F) is not recommended. To avoid condensation and
lens damage, use of the Air Purge Collar with the Water-Cooled Housing is required.
Thermalert ET Series Operator's Manual
2-5
Figure 2-6: Sensing Head with Air/Water-Cooled Housing
Figure 2-7: Air Purge Collar
2.2.3 Air Purge Collar
The Air Purge Collar accessory is used to keep dust, moisture, airborne particles, and
vapors away from the lens. It may be installed before or after the bracket (see acces-
sories drawing in Section 1.0) and screwed in fully. Air flows into the 3.2 mm (1/8”)
NPT brass fitting and out the front aperture. Air flow should be a maximum of 0.5 to
1.5 liters/sec (1 to 3 cfm). Clean or “instrument” air is recommended to avoid conta-
minants from settling on the lens.