Placement and Calibration of Sensors
Calibrating Photo-Ionization Detector (PID) Sensor
EVM Series User Manual
Calibrating Photo-Ionization Detector (PID) Sensor
PID parts per million (ppm) zero calibration
It is preferred to flush the PID ppm sensor with Zero Grade Air for a zero calibration. Alternatively, you
may flush the PID ppm sensor with Nitrogen. In clean environments (with no presence of toxic
chemicals, such as in a school setting with no toxic cleaners present) applying room air can be used to
set your zero calibration point.
For the flow rate, it is recommended to set it at 1 L/min for best response time.
PID parts per billion (ppb) zero calibration
NOTE for PID ppb sensor: The PID ppb sensor may be susceptible to baseline settlement after
more than 2 weeks of storage. In these cases, the PID PPB sensor should be operated in
clean air for several hours prior to performing a calibration and prior to performing
measurements of low concentration of gases (< 1000 PPB).
The PID ppb sensor uses a static base line for the zero offset. If the user adjusts zero base line, the PID
ppb needs to be enabled in the setup menu.
NOTE: To enable, select Setup from the main screen and then choose PID. In the PID screen,
enable the ppb zero feature. Once set, return to the calibration screen to resume the
calibration process. (For more details on setting, refer to “PID sensor setup” in Chapter 3.)
PID ppm/ppb zero cal
1. Connect the Zero Grade Air and cal cup to the EVM. (Skip this step if you are not applying a gas.)
2. From the start screen, press the Down ▼ arrow to select Calibration and press Enter
.
3. Press the ▲/▼ Arrows to select the PID sensor.
Selecting PID sensor
Cal soft key
Figure 4-27: Selecting PID sensor for calibration process
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