| QUARTZ HEATERS |
| 1)
Carbonized buildup inside heater sheath. Caused by overheating of vapors or fluids
that have accumulated in the quartz heating tube. |
| CAUSE |
SOLUTION |
| Loose cap or
conduit fitting on heater. |
Carefully clean
carbonized deposits from inside of quartz tube with damp rag on a wooded dowel. Replace
o-ring on heater cap and apply a non-hardening silicone sealant to thread area and attach
cover. Protect junction box area from dripping or condensation. |
| Degradation
of junction box. Usually caused by excessive dripping of solutions such as chromic
acid on junction box. |
Move heater in
tank, install drip shield over junction box or replace heater with model built with a CPVC
or chemically compatible junction box. |
| Junction box
melted or distorted. Too high of solution temperature or heater operated in confined
area. |
Improve
ventilation/cooling air to junction box area or raise heater up slightly above tank to
improve circulation. (as cold zone permits). |
| 2)
Buildup on the outside sheath of the element. |
| CAUSE |
SOLUTION |
| Usually caused
by localized over heating or viscous solution. Since quartz heaters transmit most of their
output through IR radiation, buildup of any type will cause overheating and reduced
service life. |
Chemically clean
any deposits from the sheath. Check the solution being heated, as a de-rated heater may be
required. |
| 3)
Tube cracked off at solution interface. |
| CAUSE |
SOLUTION |
| Usually caused
by severe thermal shock from localized overheating due to operation in air followed by
displacement immersion into a fluid. |
This is
a potentially hazardous condition. Shut off power and investigate immediately.
Element should be inspected for corrosion and electrically tested before being returned to
service. Replace tube as required. Make sure the thermal fuse is operational and replace
if necessary. |
| 4)
Tube cracked or broken off near bottom. |
| CAUSE |
SOLUTION |
| Usually caused
by tube/element assembly being physically hit or jarred, which forces the element into the
tube. This type of damage typically matches the location of the bottom spacer ring or
outside radius of the outer two elements. When hit from the inside, cracks normally
radiate outward with a larger opening on the outside of the tube. |
This is
a potentially hazardous condition. Shut off power and investigate immediately.
Element should be inspected for corrosion and electrically tested before being returned to
service. Replace the tube assembly as required. Verify that the thermal fuse is
operational and replace if necessary. Make sure that the replacement heater has a guard
installed and that the heater is moved to a safer location in the tank. |
| 5)
Tube cracked or section broken out near center. |
| CAUSE |
SOLUTION |
| This type of
damage can also be the result of severe jarring particularly if the broken tube section
matches the spacer locations. If the tube is broken in an area away from the spacers,
check for cracks that lead to a larger hole on the inside of the tube. The tube being
struck by an object in this area would cause this condition. |
This is
a potentially hazardous condition. Shut off power and investigate immediately.
Element should be inspected for corrosion and electrically tested before being return to
service. Replace tube as required. Make sure that the thermal fuse is operational and
replace if necessary. |
| 6)
Tube etched or has porous appearance on outside surface. |
| CAUSE |
SOLUTION |
| Usually caused
by operation in either a highly alkaline solution or one containing fluoride. |
Check with
chemical supplier for proper sheath material selection. Do not use quartz heaters in this
type application, as a similar future failure will result. Element maybe able to be reused
in another application provided it is inspected and electrically tested. |
| 7)
All three legs of element open, failure after a short period of operation
(less than one day). |
| CAUSE |
SOLUTION |
| Usually caused
by operation at higher than rated voltage, however, operation out of solution will cause
similar failure. Elements operating at high surface temperatures will exhibit a bluish
tint over the entire hot zone. |
Check that that
voltage being applied matches the nameplate. If it does, check the voltage code stamped on
the top 2" of the metal tubular element to make sure it matches the rated voltage.
Remember that some elements are designed with various voltage and wiring combinations to
achieve the rated voltage. Verify these findings with the factory technical sales
representatives. |
| 8)
All three legs of element open, failure after an extended period of time. |
| CAUSE |
SOLUTION |
| Usually the
result of overheating caused by low liquid level, solution viscosity or buildup on either
the inside or outside of the tube. Element will exhibit darkening over the entire hot-zone
with a bluish hue near the cold/hot transition area. View photo. |
Check thermal
fuses to verify operation and wiring, correct as required. Verify solution concentration
and operating temperature. Replace elements as required. Clean deposits off of both inside
and outside surfaces of quartz tube. |
| 9)
One leg/element open. |
| CAUSE |
SOLUTION |
| Usually caused
by a loose connection or bad element. View photo. |
Check wiring
connections and retest element. If resistance remains open, replace element. |
| 10)
Bluish spots or discoloration in cold zone transition area. |
| CAUSE |
SOLUTION |
| Usually caused
by a bad pin weld termination. |
Replace element. |
| 11)
Holes/melting of metal element sheath. |
| CAUSE |
SOLUTION |
| Usually caused
by operation in a viscous solution at high temperature or with tube surfaces covered with
some type of buildup. View photo. |
Check
application, replace with de-rated heaters and clean as required. |
| 12)
Guard melted or distorted. |
| CAUSE |
SOLUTION |
| Usually caused
by operation with low liquid level. |
Test thermal
fuses and verify wiring, operation and positioning. Remove any moisture from the thermal
well that could cause corrosion or delay the fuse response. |
| 13)
Guard material cracking at weld seams or solution interface. |
| CAUSE |
SOLUTION |
| Incompatible
solution. |
Check solution
for temperature and chemical compatibility with polypropylene. Switch to fluoropolymer or
CPVC guards as required. |
| 14)
Heaters tripping GFP/ELCB circuits. |
| CAUSE |
SOLUTION |
| Usually caused
by moisture trapped within the element insulation. |
Test insulation
value with a meggar. Should measure a resistance of at least 50 megohms between the sheath
and element. (Preferably greater than 200 megohms @ 500 VDC). If lower than noted value,
replace the heating element, as field repairs are impractical and temporary. |
| Defective
GFP/ELCB circuit. Test by running a known good electrical load through the coil to
verify operation. |
Replace as
required. |
| Low setting
on GFP/ELCB circuit. Some ground fault devices have adjustable switch settings. |
Make sure these
units are set for a minimum 5 Ma trip point. |
| Moisture
within the junction box or themowells. Remove heater cover and inspect epoxy surface,
thermal fuse and thermal well for moisture or conductive plating salts. |
Clean/dry any
deposits. Apply RTV sealant to gaskets or threaded areas and return to service. |
| 15)
Quartz heater floating up in guard. |
| CAUSE |
SOLUTION |
| Usually caused
by operation in a very dense solution. Heater junction box should be secured to guard to
prevent operation in air. |
Special tube
assemblies using a head with flange can be provided to assist in securing the heater
assembly. Since the solution is very dense, special consideration should be given to the
watt density of the element premature failure may result if the element is not de-rated. |
| 16)
Element will not fit in quartz tube. |
| CAUSE |
SOLUTION |
| Since all of the
element arrays are held together by a preformed, spacer assembly, it is highly unlikely
that a tube can be out of tolerance enough to impede insertion of the element. Most likely
cause of this apparent problem is the misconception that the entire element must be
inserted into the tube. This is incorrect as the element floats on the top of the quartz
tube by virtue of the flared portion of the potting cup. |
Make sure the
correct element length has been selected. Replace if incorrect. Carefully insert element
into quartz tube until flange of potting cup rests on top of quartz tube. Replace quartz
tube if clearance problem continues. |
| 17)
Wrong phase element ordered. |
| CAUSE |
SOLUTION |
| Since the
element array consists of three, single phase elements, in many cases it can be rewired to
either single or three phase configurations in the field by removing the silicone
insulation over the wiring connections and reorienting the copper buss bars. (Additional
buss bars may be required). |
Consult factory
for wiring details, silicone sealant/RTV can be applied to new connections to prevent
corrosion or moisture entry. |
| 18)
Thermowell tubes full of solution. |
| CAUSE |
SOLUTION |
| Any fluid inside
the Thermowell will act as a coolant and delay the switching point of the fuse device
until the fluid is boiled away. Care should be taken that the heater junction box is
sealed properly and that excessive moisture is prevented from entering. |
Periodic
inspection of the junction box and Thermowell should be considered in unusually wet
installations and for solutions operating above 180 degrees F. If solution is found in the
Thermowell, a pressure test (5 PSI max) should be performed to verify integrity. |
