MAINTENANCE, CLEANING AND CALIBRATION OF PIDS
The cell manufacturer’s application note explains when and how to maintain, clean and calibrate your PID.
The electronics in the PID-A1 and PID-AH sensor, designed to be maintenance-free, are not accessible.
Periodic sensor maintenance is required for the electrode stack and lamp.
How often does the PID require maintenance?
This depends on the environment you are measuring: if you are measuring indoor air quality with the PID-AH, where
the VOC concentrations are low and there are few particulates, a monthly or even less frequent calibration may be
adequate. However, if you are measuring high VOC concentrations with the PID-A1 and particulates are present in high
concentrations, check calibration frequently and when the PID has lost sensitivity, change the stack as explained below.
You can tell when the PID needs maintenance:
•
If the baseline is climbing after you zero the PID – replace electrode stack
•
If the PID becomes sensitive to humidity – replace electrode stack
•
If the baseline is unstable or shifts when you move the PID – replace electrode stack
•
If sensitivity has dropped too much (note the change required when checking calibration) – clean the lamp
When do I clean the PID lamp?
Cleaning of the PID lamp is recommended as the first action when presented with a PID that needs maintenance. Use the
procedure described below. It is recommended that a PID cell is recalibrated after lamp cleaning.
When do I replace the PID electrode stack?
The PID electrode stack can last the lifetime of the PID if used in clean environments, or may only last a month if used in
heavily contaminated sites. The electrode stack is a disposable item, so always hold a spare electrode stack if you are
working in a dirty environment. If the PID cell shows signs of contamination after the lamp window has been cleaned, or is
known to have been subjected to severe contamination, it should be replaced.
It is recommended that the PID is recalibrated after the stack is replaced. Instructions for replacing the electrode stack are
below.
When do I replace the PID lamp?
A PID lamp will last a long time – typically ten thousand hours and is warranted for12 months. The sensitivity of the PID is
in direct proportion to the lamp light intensity, so as a lamp ages and loses intensity, the response to a particular, low gas
concentration becomes more noisy.
Removing the electrode stack and lamp
Always use the Electrode Stack Removal Tool to remove the electrode stack; any other tools may damage your PID and
invalidate your warranty
1. Gently remove the sensor from equipment.
2. Place the PID, pellet side down, onto a clean surface.
3. Locate electrode stack removal tool into the two slots on the sides of the PID and squeeze together until electrode stack
and lamp are released.
4. Carefully lift the PID body away from the pellet and lamp.
5. Occasionally the lamp may be temporarily lodged in the cell and will need to be freed carefully with tweezers.
6. Occasionally the small spring behind the lamp will come out when the lamp is removed from the sensor. Simply replace
it into the sensor house.
Cleaning the PID Lamp
Inspection of the lamp may reveal a layer of contamination on the detection window that presents itself as a ‘blue hue.’
To check for contamination, hold the lamp in front of a light source and look across the window surface. Only clean the
lamp using our recommended lamp cleaning kit and detailed instructions. To avoid contaminating the sensor and affecting
accuracy, do not touch the lamp window with bare fingers. You may touch the body of the lamp with clean fingers.
