ENMET EX-5120 User Manual

Page 11

EX-5120

ENMET Corporation

5.2 Calibration of the EX-5120

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 several minutes for stabilization after supplying power to the

EX-5120

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-5120

transmitters.

Calibration equipment is available from

ENMET

Corporation to calibrate the

EX-5120

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.

Figure 4: Calibration Adapter EX-5120 Sensor/Transmitter

5.2.1 Zero Adjust

A ZERO function should be performed only when the

EX-5120

sensor/transmitter is exposed to fresh air. If the air at the sensor

is in question, use a cylinder of 20.9% oxygen to provide a clean air reference. Attach the cylinder to the calibration adapter.

Enter the maintenance menu by placing the magnet over

ENU

switch for 2 to 4 seconds. See

Figure 5,

EX-5120

Maintenance Menu flow chart.

The second menu available is the Zero.

Tap the

ELECT

switch to perform a Zero.

If the Zero is successful, Cal OK appears on the display and in 1 – 2 seconds, display will change to Span.
If you wish to Span the sensor Tap the

ELECT

switch you are now ready to apply gas.

Proceed to gas span step 2

If you wish to Exit the maintenance menu, Tap

ENU

switch until Exit is displayed, then tap

ELECT

switch to return to the

instrument Normal Gas Display

If the Zero is Not successful, sensor is outside of safe parameters to be zeroed, the display will read Bad Zero. Repeat
Section 5.2.1 Zero Adjust making sure to use a cylinder of 20.9% Oxygen.

Regulator

Gas Cylinder

Select

Menu

Output, for Gas

Input, for Calibration
or Optional Gas Sampling

Calibration Cover