MAINTENANCE
ELECTRIC SHOCK HAZARD. Disconnect all power
before installing or servicing heater. Failure to do so
could result in personal injury or property damage.
1.
Heaters should be checked regularly for coatings and corro-
sion and cleaned if necessary.
2.
The tank should be checked regularly for sediment around
the heater as sediment can act as an insulator and shorten heater
life.
Note:
User is responsible for maintenance schedule based on
their knowledge of the heated medium and operating conditions.
3.
Remove any accumulated sludge deposits from heater and
from tank.
4.
Check for loose terminal connections and tighten if necessary.
5
. If corrosion is indicated in the terminal enclosure, check terminal
enclosure gasket and replace if necessary. Check conduit layout
to correct conditions that allow moisture to enter the terminal
enclosure.
6.
Clean terminal ends of all contamination.
7.
The heater can be protected from possible mechanical damage by
placing a screen or grill around the elements.
8.
Protect the terminal end of the heater from spray, condensation,
dripping and vapors. A protective terminal enclosure should be
used if the heater is to be subjected to these conditions.
9.
If the heater is to be operated in the presence of explosive vapors
or dust, an explosion resistant terminal enclosure must be pro-
vided.
10.
Do not set the thermostats above the boiling point of the liquid.
The boiling liquid could create a steam pocket which could cause
the element(s) to overheat and burn out.
11.
Periodically, remove the heater from the tank to inspect the ele-
ments for signs of corrosion and remove any deposits from the
sheath.
BE SURE POWER IS DISCONNECTED BEFORE
REMOVING ELEMENTS.
12.
Be sure the sheath material is compatible with the material being
heated. Copper sheathed elements are used to heat water. Steel
sheath elements are used to heat oil, alkaline, wax and other sim-
ilar materials. Stainless steel and Incoloy sheathed elements are
most often used for heating water and corrosive solutions. Check
with the supplier of the material or factory for a recommendation
of a suitable sheath material.
13.
Make sure the watt-density of the heater is suitable for the mate-
rial being heated. The velocity, viscosity, thermal conductivity
of the material and operating temperature are all factors in deter-
mining the allowable watt-density of the element. Consult facto-
ry if in doubt about the proper watt-density for the heater in a par-
ticular application.
14.
When heating liquids in a large tank, the use of several small
heaters will provide more uniform heat distribution than a single
large heater.
OPERATION
1.
Do not operate heaters at voltages in excess of that stamped on
the heater since excess voltage will shorten heater life.
2.
Always maintain a minimum of 2” of liquid above the heated
portion of the element to prevent exposure of the effective heat-
ed length. If the heater is not properly submerged, it may over-
heat and shorten heater life. DO NOT OPERATE HEATER IF
DRY.
3.
Be sure all trapped air is removed from a closed tank. Bleed the
air out of the liquid piping system and heater enclosure prior to
energizing.
Note:
The tank or heating chamber in closed tank systems
must be kept filled with liquid at all times.
4.
Keep heating elements above sediment deposits.
5. Low Megohm Condition —
The refractory material used in
electric heaters may absorb moisture during transit, storage or
when subject to humid environments that will reduce the cold
insulation resistance (low megohm). Low megohm may result in
high leakage current to ground and nuisance trips of ground fault
protection equipment. Normally, the megohm value increases
after heat-up.
Typical insulation valves are 5 megohm or greater on complete
assemblies of unsealed elements or 20 megohm on individual
unsealed elements. It is recommended that heaters with 1
megohm or less be dried out before applying full power. If dried
properly low megohm will not effect heater life or efficiency.
To correct a low megohm condition, remove terminal enclosure
cover, gaskets, and terminal hardware. Bake heaters in an oven at
300 to 350˚F for several hours or preferably overnight.
An alternate procedure is to cycle the heater in 10 to 15 minute
periods at low voltage until megohm values are normal. Sheath
temperatures should not exceed 350˚F.
Note:
Low megohm on heating elements with epoxy or hermetic
seals cannot be serviced in the field. Typical resistance
values when sealed are 200 megohm or greater. Contact Chromalox
service center at number listed.
When using an element sheath thermocouple, be sure to install
flange with the imprinted “TOP” designation directly upward.
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