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CAUTION
Troubleshooting and repair should only be
attempted by qualified maintenance personnel.
The nature of the ceramic insulators used to electrically
isolate and support the nickel chromium resistance wire in
the heating elements is such that over a long period of
storage, they will absorb considerable moisture from the
atmosphere unless the pipe and conduits are sealed. It is
recommended to perform an insulation resistance test prior
to energizing the equipment. If the value is less than 1 Meg
Ohm using a 500Vdc or similar tester, care must be taken to
dry out the heater to prevent failure. It is recommended that
the elements be turned on at a reduced voltage at first, to
boil off the moisture. Meg Ohm readings may drop initially
WARNING – Explosion Hazard
INDEECO strongly recommends installation be performed
by qualified personnel familiar with the National Electrical
Code and all local codes and standards regarding
explosion-proof equipment. It is the responsibility of the
installer to verify the safety and suitability of the
installation.
Per article 500-516 of the National Electrical Code, a
hazardous area is defined by a "Class", "Division", "Group",
and "Temperature Code". The Class can be I or II, where
Class I indicates that the hazard classification is due to the
presence of an explosive vapor. Class II indicates an
explosive dust. The division can be either 1 or 2. Division 1
indicates a hazard is ALWAYS considered to be present.
Division 2 means the hazard is only present under abnormal
conditions. The Group defines the explosiveness of the
hazard. The Temperature Code specifies the temperature at
which a hazard will ignite.
INDEECO can provide designs suitable for all of the above
conditions, but a heater should never be placed in an
environment not noted on the heater nameplate.
NEVER operate the heater in an atmosphere with an ignition
code temperature LOWER THAN the nameplate rating. The
user must determine the actual area classification.
Special design considerations for electric heaters used in
hazardous locations:
1. Locate all electrical connections in an appropriate
enclosure.
2. Prevent surface temperatures of the heater from
exceeding the design ignition temperature.
INDEECO Storage Tank Heaters designed for hazardous
locations are typically provided with a purged terminal
enclosure.
TROUBLESHOOTING
after a few minutes of operation, indicating moisture being
forced out of the elements. The terminal enclosure lid
should be left open during this period to allow the moisture
to escape.
If the heater has a manual-reset high limit thermostat, be
sure that the reset button is pressed in.
If reduced heat output is suspected, verify the condition of
the heating elements by using an ammeter to check the
current draw of each input line. All input lines should draw
approximately equal current, which should agree with
nameplate rating. If they do not, one or more of the heating
elements could be damaged.
HAZARDOUS AREAS
(where applicable)
When the design temperature of the process exceeds the
rated ignition temperature, it is critical that the heater and all
customer piping is properly insulated.
A hazardous area heater must be powered and controlled by
a heater control panel designed to provide necessary over-
temperature safety interlocks. Contact INDEECO if
assistance is required to properly control and protect the
heater.
Never apply power to a heater in a hazardous atmosphere
unless all terminal box covers are properly installed with all
cover bolts.
All conduits entering the heater terminal box must be sealed
within 18" of the heater using an explosion-proof conduit seal.
Any unused openings must be properly sealed with a steel
pipe plug. Follow the NEC for specific conduit requirements
such as the requirement for Rigid Conduit.
To ensure proper flamepath, all threaded conduits must use
rated fittings and be tight, with a minimum of 5 good threads
engaged. Any machined metal-to-metal surfaces on terminal
boxes must be handled carefully to prevent scratches which
may void the explosion-proof rating.
Operating the heater at a voltage higher than the
nameplate value may result in elevated
temperatures and amperage above the design
ratings.
Proper grounding of equipment in hazardous areas is critical
to eliminate potential sources of sparking.
Replacement of electrical components should only be done
by authorized personnel familiar with the requirements of
maintaining electrical equipment in an explosion-hazard area.
7
WARNING - Risk of Explosion
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