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MARLOX® THERMOCOUPLES
Metal Sheathed - Inert Oxide
Insulated
THERMOCOUPLE ASSEMBLIES
I.
GENERAL INSTALLATION PARAMETERS
Handling:
There are
many variations of thermocouples and thermocouple assemblies.
Even though some may appear to have heavy duty protecting tubes
or thermowells, the internal parts can be delicate. Care in handling
is a must to insure the sensor integrity. DO NOT DROP. Thermocouples
are carefully packed at the factory. Inspect the package when
receiving for indications of shipping damage. If shipping damage
is noticed report it immediately to the shipping company and make
the necessary reports. Marlin ships on a FOB factory basis therefore
it is your responsibility to file any claims. Hidden shipping
damage can also occur (no evident sign of mishandling). If after
carefully opening the package, damage is discovered, save all
product and shipping material then notify and file the proper
claims with the shipping company immediately.
Storage:
Store in
a dry, clean place. Avoid areas where dropping or stacking may
occur.
Location:
The thermocouple
should "see", as closely as possible, what the product in the
process is experiencing in order to get meaningful temperature
measurements. Locate the thermocouple as close to the product
as possible. A rule of thumb is to
have at least 10 tube diameters immersion in the hot zone.
Avoid direct flame impingement or stagnant areas.
Installation:
DO NOT
ATTEMPT to mechanically connect the assembly into the process
by tightening at the terminal or connecting head. USE ONLY
THE PROCESS FITTING OR THE THERMOWELL FLATS FOR THIS PURPOSE.
Terminals or connecting heads that are twisted can be damaged
or cause shorts that can adversely affect the operation of the
thermocouple. If a thermowell or protecting tube must be welded
into the process, carefully remove the thermocouple sensor before
welding and be sure to handle carefully, keep clean and replace
without forcing or stressing any components. Assemblies with ceramic
tubes should be preheated before immersion into high heat in order
to avoid any thermal shock.
II.
GENERAL MAINTENANCE PARAMETERS
Regularly
scheduled maintenance procedures should include inspection and
calibration intervals so that life and reliability of the instrumentation
is improved and the likelihood of sudden serious failure is
reduced. These procedures should be set up by the responsible
engineering department and performed by personnel that are familiar
with the operating principles upon which the system is based.
DO NOT LUBRICATE.
Thermocouples
often deteriorate with time, exhibiting a drift from actual
temperatures. Deterioration usually is more rapid at higher
temperatures and depends on the integrity of the protecting
tube or sheath to isolate it from contaminates. Thermocouples
should be checked at regular maintenance intervals based on
recommendations or on experience.
III.
WIRE EXTENSIONS
Use wire
extensions of the same thermocouple material type (i.e. "J",
"K", "T", "E", "R", "S", "B", etc.) of the installed thermocouple
throughout the circuit. The use of thermocouple grade or thermocouple
extension grade wire and the selection of conductor insulation
depends on what the environmental conditions dictate.
For
more information regarding Thermocouple Wire - Please Click
Here!
"RED" color code is always negative
in thermocouple circuits. Ideally run thermocouple circuit wires
in separate conduits at least one foot away from power lines.
Twisted and shielded constructions may be required to avoid noise
in the thermocouple circuit. The overall impedance of the thermocouple
circuit must be compatible with your instrumentation. If there
is a reversal in the thermocouple circuit the indication will
be down scale. A "double-reversal" in the circuit will give an
upscale but erroneous reading. Keep the "RED"
color coded leg negative throughout the circuit to avoid these
reversals.
For
more information regarding Marlox Thermocouples,
Please consult your Marlin catalog, Pages C-21 to C-44.
If
you do not have a Marlin Catalog - Click
Here!
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