head as specified for pipe thermocouples. Protecting tube shall be as
specified under thermowells. Bearing thermocouples shall have Type J
ungrounded element with 20 AWG iron-constantan wires and 25 mm one inch
insulator cemented over measuring junction. Element shall be mounted in 5
mm 3/16 inch spun and welded copper tube, sealed at open end. Head shall
be as specified for pipe thermocouples. Surface thermocouples shall have
ungrounded Type K element (chromel-alumel) at least 20 AWG suitably
protected from high temperatures using fiberglass insulating jacket.
2.12.5.3
Detector shall be three lead resistance sensor with protective sheath and
screw terminal head for pipeline mounting in a thermowell. Accuracy shall
be plus or minus 1/2 degree C 1 degree F or plus or minus 0.5 percent of
reading, whichever is greater. Element material and nominal resistance
shall be 10 ohm copper. Head shall be universal type with screwed cover,
chain, and terminal connector. Provide stainless-steel nipple as required
for head to clear insulation by at least 50 mm 2 inches. Element length
shall be as required for the insertion depth and insulation thickness
specified. Provide thermowell sized for the element in accordance with the
thermowell specification.
2.12.5.4
Thermowells
**************************************************************************
NOTE: General. Provide thermowell for each
temperature sensing element (thermometer,
thermocouple, remote bulb, etc.) unless otherwise
noted.
Insertion:
Piping: 65 mm minimum, 150 mm 2 1/2 inch minimum, 6
inch maximum unless otherwise noted.
Ductwork: At least 1/2 duct depth but not over 910
mm 36 inch unless otherwise noted.
Lagging extension neck: As required to keep well
wrench flats clear of insulation.
Protection: Provide cardboard inserts in each well
to prevent internal damage prior to installing
thermometer in installed well.
Pipeline Wells:
Bore:
Straight or tapered bore sized to fit sensor.
Material:
316 stainless steel unless otherwise
noted.
Ratings: Submit pressure vs. temperature and
velocity vs. insertion length ratings for each type
of well furnished. Submit calculations (to verify
that wells are safe for the specified conditions)
for special wells for which ratings are not
available.
SECTION 15864N
Page 95
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