Analytical Industries GPR-2500 Series Oxygen Transmitter - Manual (Page 26)

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Factory Default Zero:
The software will eliminate any previous zero calibration adjustment and display the actual the signal output of the
sensor at a specified oxygen concentration. For example, assuming a zero gas is introduced, the display will reflect
an oxygen reading representing basically the zero calibration adjustment as described above. This feature allows
the user to test the sensor’s signal output without removing it from the sensor housing.
MAIN MENU
AUTO SAMPLE
MANUAL SAMPLE
CALIBRATE
24.5 C 100 KPA
>>>
CALIBRATION
SPAN CALIBRATE
ZERO CALIBRATE
DEFAULT SPAN
DEFAULT ZERO
24.5 C 100 KPA
Span Calibration
Maximum drift from calibration temperature is approximately 0.11% of reading per °C. The transmitter has been
calibrated at the factory. However, in order to obtain reliable data, the transmitter must be calibrated at the initial
start-up and periodically thereafter. The maximum calibration interval recommended is approximately 3 months, or
as determined by the user’s application.
Calibration involves adjusting the transmitter electronics to the sensor’s signal output at a given oxygen standard,
e.g. a certified span gas with an oxygen content (balance nitrogen) approximating 80% of the next higher full scale
range above the intended measuring range is recommended for optimum accuracy, see Calibration and Accuracy.
Calibration with ambient or instrument air (20.9% or 209,000 ppm) is recommended when installing a new sensor
or when a certified gas is not available.
GPR-2500 General Service:
In standard configuration, the GPR-2500 can be calibrated by exposing the sensor to the readily available cost
effective and reliable 20.9% (209,000 ppm) oxygen concentration of ordinary atmospheric air or a certified span
gas with an oxygen concentration of 80-100% of full scale range balance nitrogen. For example, for a 0-25%
range, the span gas should be a certified grade between 19-23% oxygen preferably approximately 20.9% oxygen.
Caution: Regardless of configuration to assure proper grounding, connect the 4-20mA signal output to the external
device (PLC, DCS, etc.) before attempting any zero or span adjustments.
GPR-2500MO Medical Grade Oxygen:
For optimum accuracy calibrate (zero and span) the transmitters and then repeat both the zero and span
calibration after the transmitters has been allowed to stabilize for 24-36 hours after the initial calibration.
Caution: Do not attempt to span the transmitters with air or 21% oxygen and then operate it for either elevated
or high purity oxygen measurements – select one of the following recommendations.
Certification of medical grade oxygen: As mandated by the FDA, requires the use of certified zero (99.9% nitrogen
minimum purity) and span (99.2% oxygen minimum purity). For optimum accuracy and to take advantage of the
transmitters’ inherent accuracy of 0.1%, perform the zero and span calibration before each certification. Otherwise
calibrate every eight (8) hours.