Specifications

WATLOW IND. WATROD Duct Heater Installation & Maintenance Manual
I&M NUMBER: 316-42-6-1 Page: 3
Date:6/11/2008 Rev: 3.00
________________________________________________________________________________________________________________________________________________________________________________________________________________________
WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]
In hazardous locations, (as defined in NFPA 70 NEC, Article 501 or other similar standards global
standards) explosion resistant housings must be used.
In order to maintain termination integrity, the terminal enclosure should be kept below the maximum
temperature rating of the internal components. Insulation should not be added to the bare external
surfaces without consulting the manufacturers.
5. Torque Values for Terminal Connections
To prevent arcing it is important that all of the terminals connections be tightened, whether it the
individual element terminals or the connection blocks.
Watlow recommends the following torque specifications for the tin plated aluminum feeder wire
connection blocks:
For #4-#6 AWG – 45 inch/pounds
For #8 AWG – 40 inch/pounds
For #10-#14 AWG – 35 inch/pounds
The #10-32 threaded hex nuts on the individual element terminals need to be tightened to 20
inch/pounds.
Figure #1
Tin Plated Aluminum Connection Blocked with lead wire
6. Gasketing
It is important to completely seal off the process air flow from the terminal enclosure using a gasket. For
air applications we recommend the following gaskets depending on the process temperature.
Process Thickness Material ASTM F104
Temperature (°F) Line Call Out
Up to 370°C (700 °F) 1/8”(3.18 mm) Compressed Asbestos-Free F712100A9B4E22K5M6
Fiber Reinforced
Up to 500°C (932 °F) 1/8”(3.18 mm) Flexible Graphite F517100B1M3
For applications other than air or at higher temperatures consult the factory or a gasket manufacturer.
If the opening in the duct work is larger than the area required for the duct heater, the terminal area may
be exposed to air at temperatures which exceeds the terminal enclosures rating. Therefore, it is
recommended that gaps the duct and the heater be sealed off using tadpole gaskets that are rated to the