All gas detectors require periodic calibration to compensate for sensor variations over time. Calibration aligns the sensor signals to the instrument display. For example, if an instrument is exposed to 100 ppm CO, the instrument display should read 100 ppm. If it doesn't, the act of "instrument calibration", correctly executed, makes it do so.
Calibration is performed by applying a known calibration gas to an instrument and dialing a potentiometer or pushing buttons to make the instrument read what it should. Calibration should only be performed by suitably trained individuals.
Care should be taken to closely follow the calibration procedure provided in the ENMET instrument manual and to use the proper calibration gas and adapters. Some instruments or sensors may require special blends of gases, a specific background gas, or absence of a particular background gas. Failure to use the proper type or concentration of gas can cause an inaccurate calibration and therefore improper instrument readings or calibration faults. Using an improperly calibrated instrument could result in severe injury or death.
"Field Tests" are highly recommended. A field test is application of test gas that is typically higher than the instrument's alarm point for a given gas. This field test gas may come with a single gas in a single cylinder or may be a multi-gas blend.
The field test procedure follows the same technique of applying gas as the calibration procedure. The difference is that no adjustments are made to the instrument calibration, and the cylinder(s) used for field test may or may not be the same ones used for calibration.
Field tests ("field check", "bump test" or other equivalent term) should be performed on at least a monthly (30 day) basis. The more often an instrument is in service or if in use in harsh environments, the more frequently it should be field tested.
Calibration of ENMET instruments should be performed at the frequency stated on the following page. While these are recommended calibration intervals, calibration on a more frequent basis is acceptable and can improve the accuracy of the instrument. Sometimes a calibration interval can be extended if more frequent field tests are performed and the instrument satisfactorily passes those tests.
ENMET Instrument Calibration and Field Testing, cont.
Portable Instruments
Instrument
Version
Recommend CalibrationInterval
MX-2100
All
3 months
Target
All
3 months
OMNI-4000
All
3 months
QUADRANT
All
3 months
CGS-90/90R
B, F calibration
3 months
CGS-90/90R
C calibration
1 month
CGS-80/80R
A, B calibration
3 months
CGS-80/80R
C calibration
1 month
CGS-100/100SP
A, B calibration
3 months
CGS-100/100SP
C calibration
1 month
CGS-20M
A, B calibration
3 months
CGS-20M
C calibration
1 month
EX-2000
All
3 months
C-2000
All
3 months
TX/OX-2000
All
3 months
SMARTLOGGER
All
3 months
TOXIMET
All
3 months
SPECTRUM/SPECTRUM SP
All
3 months
Stationary Instruments
Instrument Model
Recommended calibration interval
ENGUARD
3 months
MX-32/42/48/52 Systems
3 months
EX SE/ND/MRI-5100/5150/5175
3 months
EX-5000 Transmitters
3 months
EN/SDS/SDS-97D Series Transmitters
3 months
ISA-44/44 Systems
3 months
ISA-40
3 months
SPECTRUM On-Line
3 months
Respiratory Instruments
Instrument Model
Recommended calibration interval
MED-AIR 2200
3 months
MED-AIR 2000
3 months
ISA-300-RAL
3 months
ISA-200-RAL
3 months
ISA-100-RAL
3 months
ISA-RAL-M
3 months
ISA-34/36/44-RAL
3 months
SPECTRUM-RAL
3 months
Calibration should be performed on a more frequent basis if the instrument is exposed to temperature extremes or is subjected to a physical shock. If you suspect the accuracy of an instrument may be in question, perform a calibration before use. Every instrument listed above must be recalibrated whenever a sensor is replaced, with the exception of SMARTBLOCKS in the SMARTLOGGER and OMNI-4000 instruments.
