Oldham OLCT 200 User Manual page 73

addressed by polishing the lamp window with alumina powder. See cleaning kit P/N
78105025
Effect of Temperature
The response of the OLCT200 PID can be significantly affected by temperature. Most
significantly, in environments below 0°C the measurement can be +50% or more of the
actual gas concentration. As a result, it is highly recommended that OLCT200 PID be
calibrated often and when seasonal temperature changes occur.
Effect of Humidity
Water is not itself detected by PID; However, water absorbs a portion of the light that
otherwise promotes a response from a photo-ionizable gas.
The response of the OLCT200 PID to humidity can be seen in the figures presented
below, for Fahrenheit and Celsius temperatures. For example, it can be seen that at
80°F and 90% relative humidity (RH), a response is decreased from that in dry air by
20%. This effect will be the same for any detectable gas.
Maintenance
The electronics in the OLCT200 PID sensor are designed to be maintenance-free and
not accessible. Periodic sensor maintenance is required for the Mini Pellet and the
lamp.
The OLCT200 PID lamp will need occasional cleaning. How often depends on the
environment you are measuring. If you are measuring indoor air quality where the VOC
concentrations are low and there are few particulates, then a monthly or even less
frequent calibration may be adequate. However, if you are measuring high VOC
concentrations and particulates are present in high concentration then check
calibration frequently and when the PID has lost sensitivity or error state shows,
change the stack as explained below.
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