Manual

Sample-Draw Hydrogen Sulfide Gas Detection • 15
Setting the Zero Reading
1. Open the clamp, then connect the sample tubing from the gas collection bag to the
sample-draw detector’s inlet line. This step is not necessary if you verified a fresh
air environment earlier in this procedure.
2. Allow the reading to stabilize for approximately 1 minute.
3. Verify a voltmeter reading of 100 mV (± 2 mV).
4. If necessary, use a small flat-blade screwdriver to adjust the zero potentiometer until
the voltmeter reading is 100 mV (± 2 mV).
5. Allow the sample-draw pump to draw out any residual gas in the gas collection bag.
Steps 6 through 8 are not necessary if you verified a fresh air environment earlier in
this procedure. Go to step 9.
6. Disconnect the sample tubing from the inlet line, then close the clamp.
7. Connect the sample tubing from the gas collection bag to the fixed flow regulator,
then open the clamp.
8. Screw the fixed flow regulator onto the calibration gas cylinder. The gas collection
bag begins to fill.
9. Unscrew the fixed flow regulator from the cylinder when the gas collection bag
appears full.
10. Close the clamp, then disconnect the sample tubing from the fixed flow regulator.
Setting the Response Reading
1. Open the clamp, then connect the sample tubing from the gas collection bag to the
inlet line at or near the sample-draw detector’s INLET fitting.
2. Allow the sample-draw detector to respond to the calibrating sample for
approximately 1 minute.
3. When the reading on the voltmeter stabilizes, verify that the reading matches the
response reading (±2 mV) you determined earlier.
4. If necessary, use the span potentiometer on the amplifier to adjust the reading to
match the correct response reading.
5. Allow the sample-draw pump to draw out any residual gas in the gas collection bag.
6. Disconnect the sample tubing from the sample-draw detector’s inlet line, then close
the clamp.
7. Reconnect the incoming sample line.
8. Wait 1 to 2 minutes to allow the hydrogen gas reading to decrease and stabilize.
9. Store the components of the calibration kit in a safe and convenient place.