ENMET EX-5150-MOS - Manual (Page 11)

EX-5150-MOS ENMET Corporation
9
5.2 Calibration of the EX-5150-MOS
Calibration is the process of setting the instrument up to read accurately when exposed to a target gas. The Zero function sets
the clean air reference point and the Span function sets the sensitivity of the instrument.
Initial Calibration: Wait 24 hours after initially supplying power to the EX-5150-MOS sensor/transmitter (S/T) before initial
calibration. The S/T has been precalibrated at the factory, and initial field calibration should result in only fine tuning to circuit,
as well as a way to check that installation is successful. It is not necessary to open the enclosure to make adjustment. The
calibration functions are operated with magnets from outside the enclosure through the
MENU and SELECT switches. Do Not
open the S/T unless the area is de-classified.
Calibration Zero and Span functions are two separate procedures. They operate independently of each other. It is
recommended that the Zero procedure be done prior to the Span procedure.
ENMET Corporation recommends at least
quarterly calibration of the EX-5150-MOS transmitters.
Calibration equipment is available from ENMET Corporation to calibrate the EX-5150-MOS sensor/transmitters. A
calibration adapter will have a fitting for the gas cylinder on one side, and a cover to go over the sensor housing on the other.
Generally, a cylinder of 20.9% Oxygen is used to provide a fresh air reference or Zero point for the calibration. Another
cylinder is used to provide the Span reference point for calibration. Depending on the instrument calibration, the Span gas may
be the same gas that the instrument is calibrated to display, or it may be another gas, which
ENMET has found to have a similar
response. Sensors require a humidified calibration gas sample. Fill the humidifier bowl, half way up with clean fresh water
prior to attaching the Zero or Span gases. Be careful not to let the humidifier bowl tip, allowing water to enter the gas delivery
tubing. See Table 3 for standard and Non-standard calibration gases.
N OTE : Gas flow is opposite to arrow on humidifier
Figure 4: Calibration Adapter EX-5150-MOS Sensor/Transmitter
Calibration Cover
See insert below for
proper gas flow
Humidifier
S e le
c t
M
e n u
Select
Menu
Regulator
Gas Cylinder
Humidifier Top View
T O C AL C OVER
& S ENSOR
F ROM
R EGULATOR &
G AS CYLINDER