ENMET EX-5175 - Manual (Page 12)

EX-5175-EC ENMET Corporation
8
Regulator
Gas Cylinder
Select
Menu
Output, for Gas
Input, for Calibration
or Optional Gas Sampling
Calibration Cover
5.2 Calibration of the EX-5175-EC
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-5175-EC 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-5175-EC transmitters.
Calibration equipment is available from ENMET Corporation to calibrate the EX-5175-EC 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.
N OTE : Zero function is Not applicable for Oxygen sensor/transmitters.
Figure 4: Calibration Adapter EX-5175-EC Sensor/Transmitter
Table 2: Examples of S/T ranges, alarm Points and Calibration Gas
Gas Range Alarm 1* Alarm 2* Alarm 3* Cal Gas
Ammonia 0 – 100 PPM 25 PPM 50 PPM 75 PPM 25 PPM NH3
Carbon Monoxide 0 – 500 PPM 35 PPM 50 PPM 200 PPM 100 PPM CO
Hydrogen 0 2000 PPM 200 PPM 500 PPM 1000 PPM 800 PPM H2
Hydrogen Sulfide 0 – 100 PPM 10 PPM 20 PPM 50 PPM 20 PPM H2S
Oxygen 0 – 30% by Vol 17% by Vol 19.5% by Vol 23.5% by Vol 20.5% by Vol
Sulfur Dioxide 0 – 300 PPM 20 PPM 50 PPM 100 PPM 100 PPM SO2
If not listed consult ENMET Distributor or ENMET Corp for additional information
*N OTE : These internal sensor/transmitter alarms are independent of the 4-20mA Controller alarm point settings.