CHAPTER
6
Calibration
Guidelines
Recommended gas mixture:
CO: 100 ppm balance N
2
H
2
S: 25 ppm balance N
2
LEL: 50% LEL or 2.5% by vol. methane balance air
O
2
: clean air, 18%
l To ensure accurate calibration, use a premium-grade calibration gas. Gases approved by
the National Institute of Standards and Technology (NIST) improve the validity of the
calibration. You can use a 34 L cylinder (PN: CG-Q34-4) or a 58 L cylinder (PN: CG-Q58-4)
l Do not use a gas cylinder past its expiration date.
l Calibrate a new sensor before use. Install the sensor, activate the detector, and allow the
sensor to stabilize before starting calibration or a bump test.
Used sensor: 60 seconds / new sensor: 5 minutes.
l Calibrate the detector at least once every 180 days, depending upon use and sensor
exposure to poisons and contaminants.
l Calibrate the detector if the ambient gas varies during startup.
l Calibrate only in a safe area that is free of hazardous gas.
l Do not calibrate the detector during or immediately after charging is complete.
l The H
2
S (PN: SR-H-MC), CO (PN: SR-M-MC), LEL (PN: unfiltered SR-W-MP75; filtered SR-
W-MP75C), and O
2
(PN: SR-X2V), sensors can be automatically zeroed each time the
detector is activated if the Auto-Zero on Startup option is enabled. Activate the detector in a
normal (20.9%/20.8% O
2
) atmosphere.
l If a certified calibration is required, contact BW Technologies by Honeywell.
l Calibration can be performed using either a 0.5 l/min manual regulator (PN: REG - 0.5) or
a demand flow regulator (PN: REG-DF-1)
l The maximum hose length for calibration is 3 ft (0.9 m).
BW MaxXT II 70 User Manual
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