Watlow WATROD Over-the-Side - Manual (Page 2)

WATLOW IND.
WATROD Over-the-Side Installation & Maintenance Manual
I&M NUMBER: 316-42-9-1 Page: 2
Date: 6/11/2008 Rev: 2.00
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WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE 573-221-2816 n FAX 573-221-3723
Failure of components in a temperature control loop, such as the sensor, heater control relay or main
temperature control, can result in damage to a product in process, a melt down of a heater, and / or
damaging fire.
To protect against this possibility, over temperature protection must be provided to interrupt or remove
power from the heater circuit. A bulb and capillary thermostat is not recommended for this function
since it may not respond quickly enough to adequately protect the heater. In cases where the
thermostat bulb gets too hot before the system is turned off, the thermostat bulb could rupture.
This could result in the thermostat remaining in the "ON" condition since there is insufficient
fluid to move contacts apart. We recommend the temperature protection have appropriate third party
approval, and be applied in the classification for which it was tested and approved.
Over-the -side heaters are susceptible to damage due to fluctuation of tank level. In order to help
prevent premature failure and a potentially hazardous condition in cases where consequences of failure
may be severe, use an appropriate third party approved liquid level protection device. The liquid level
should be such that the entire heater is fully submerged with enough liquid above the heater to
adequately dissipate heat from itself as under normal operating conditions. Consult your local authorized
sales representative for specific recommendations for your application.
3. Terminal
Enclosures
Terminal enclosures should be selected to be compatible with the environment in which the heater will
be located. It is the users responsibility to determine the need for correct rating of the electrical housing.
This should be based on appropriate national and local electrical codes. Failure to use a compatible
enclosure could result in heater damage and personnel danger.
Standard terminal enclosures on "L" ,"O", and Vertical loop heaters are supplied with enclosures rated
for NEMA 4 applications. The drum Over-the-side heaters are supplied with NEMA 1 general purpose
enclosures. These enclosures should be applied where there will be no danger of spilled liquids,
dampness, dirt, and gaseous conditions. Enclosures for wet or hazardous locations are also available for
the drum Over-the-side heaters but must be installed at the factory.
Although enclosures are supplied over the terminals, units should be located in an area that will minimize
the chance of being hit by falling or moving objects.
In hazardous locations, (as defined in NFPA 70 NEC, Article 501) explosion resistant housings must be
used.
In order to maintain termination integrity, the terminal enclosure should be kept below 400
°F
(204
°C).
4. Orientation / Mounting
Heater orientation is important in order to ensure efficient heat transfer and safe operation. Care should
be taken to allow enough room for heater expansion without compromising heat transfer. When installing
the heater into the tank, be sure that the heater is stable and setting solidly on the tank bottom or being
held to the tank wall rigidly. Consideration should also be given to sludge build-up in the bottom of the
tank and the need for heater removal (replacement or maintenance). Location of the heater in the sludge
area will cause premature failure and lower heat transfer efficiency.
Figure # 1 shows the proper location in relation to the liquid level in the tank for proper installation.
The heated section of the Over-the-Side heater must be immersed during operation or premature
failure may result. The use of an approved high limit device is highly recommended, together with a
liquid level control where fire and/or physical damage or injury could occur.