VESDA
VESDA Sensepoint XCL – Large Bore Installation Manual
35563_02
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4. Perform zero calibration.
a. Hold the UP button for 2 seconds.
b. If there is any doubt of the quality of the ambient air, connect a cylinder of fresh air to the detector.
c. Apply fresh air to the detector, and wait for a few minutes until the reading is stable.
d. Using the UP and DOWN buttons, adjust the output voltage so that the voltmeter is reading slightly
above zero, and then decrease the reading slowly so that it reads zero.
e. When the output voltage is adjusted close to zero, accept the zero calibration by holding UP button
for 2 seconds.
5. If a span calibration is required, after successful zero calibration it will move to span calibration
automatically. If a span calibration is not required, exit from calibration by holding DOWN button for 5
seconds. This will cancel a span calibration while zero calibration result sustains.
a. Hold UP button for 2 seconds.
b. Connect a cylinder of span gas to the detector. Where the greatest accuracy is required, the cylinder
concentration should be usually around the alarm set point or 50% of the range of the detector.
c. Apply the span gas to the detector, and wait for a few minutes until the reading is stable.
d. Using the UP and DOWN buttons, adjust the output voltage until it reaches the target value. Use the
formula below to calculate what the correct voltage should be:
Vout = Gas concentration ÷ detector range
For example, if you are applying 45% LEL gas with a 100% LEL detector range, you would need to adjust
the voltage output so that the reading on the voltmeter shows: 45 ÷ 100 = 0.45 V.
e. When the output voltage is adjusted close to target gas concentration, accept the span calibration by
holding UP button for 2 seconds.
6. Purge the gas sensor.
a. Hold the UP button for 2 seconds.
b. Remove the span gas from the detector and make sure that the reading voltage out returns to zero. If
there is any doubt that the detector is not in clean air, apply cylinder air. Otherwise, an alarm may
occur.
7. Use the cancel function to return to normal monitoring mode.
8.
Assemble the detector module to the back box.
Note:
Perform calibration (i) after installation, (ii) after sensor cover or gas sensor replacement, (iii) every
6 months (strongly recommended), (iv) when detector fails bump test. See section “4.8
Troubleshooting”.
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