ENMET EX-5185 User Manual

Page 11

EX-5185-PID

ENMET Corporation

5.2 Calibration of the EX-5185

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-5185

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

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-5185

transmitters.

Calibration equipment is available from

ENMET

Corporation to calibrate the

EX-5185

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, typically Isobutylene. 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. See

Table 3 for standard calibration gases.

Figure 4: Calibration Adapter EX-5185 Sensor/Transmitter

Regulator

Gas Cylinder

Select

Menu

Output, for Gas

Input, for Calibration
or Optional Gas Sampling

Calibration Cover