ENMET ISA-44-RALE-OD - Manual (Page 26)

ENMET Corporation ISA-44RALE-OD/ISA-44RAHE-OD/ISA-44E-OD
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5. FULL SCALE ADJUSTMENT:
a) Leave the negative lead of the voltmeter at TP101 and connect the positive lead to TP102 on the main circuit
board.
b) Adjust the gain potentiometer on the Control unit to give 1.24 V DC between TP101 and TP102.
c) Adjust the meter full scale potentiometer R110 so the meter on the front panel reads full scale, 26% (adjust this
pot. counterclockwise to increase, clockwise to decrease.
d) Remove the voltmeter leads from the test points.
6. ALARM SET ADJUST:
a) Adjust the oxygen gain potentiometer on the control unit to predetermined alarm point (19.5%) on the oxygen
meter.
b) Adjust the alarm point adjust potentiometer, R116, counterclockwise until the oxygen circuit just goes into
alarm. The red oxygen deficiency LED should just activate. NOTE: If the alarm LED is on before you begin the
potentiometer adjustment, adjust this pot. clockwise until the LED is off, then readjust counterclockwise until
the LED just activates.
c) Adjust the oxygen gain potentiometer down so that the oxygen circuit comes out of alarm. Then adjust up again
slowly until the unit goes into alarm.
d) Adjust the oxygen gain potentiometer so that the meter reads 20.9%.
7. The oxygen circuit alignment is now complete. Turn the horn back on.
6.3 Routine Gas Test and Recalibration ISA-44E-OD
Test and/or recalibrate the ISA-44E-OD periodically and whenever a sensor receives severe handling.
Use only the equipment listed. Follow the test and calibration procedures carefully.
MATERIALS:
q
one 17 l (propane torch size) cylinder high-level alarm calibration gas with air used as background gas, such as
10% LEL methane in air.
N OTE : Gas should be identical (or equivalent) to that used to calibrate the unit, unless you want to recalibrate to a new
gas or different concentration. Do not use inert gases, such as nitrogen or argon.
q
gas calibration fixture (regulator, sensor cover, tubing, humidifier/flowmeter; ENMET part no. 03700-001).
q
small screwdriver (for adjusting potentiometers)
q
water
Figure 9: Calibration Adapter ISA-44E-OD
Calibration Cup
(Fits over the sensor)
Sensor Enclosure
Calibration Fixture
Humidifier
To Cal Cup
To cylinder
Calibration
Valve
Cylinder Calibration
Gas or Oxygen
Tube
Flowmeter
Sensor