© 2018 All rights reserved. Data subject to change without notice.
39
Rev. B | 2018.08
LPT-P- Operation Manual
7 CALIBRATION
7.1 Calibration Specifi cations
7.1.1 Gas
Calibration span gases should have at least ± 5% accuracy and have a current date stamp.
Gas generators should have a current dated cell installed. Service personnel should fl ow zero
emissions air or 20.9% volume O
2
(scrubbed of hydrocarbons) before attempting to null adjust
toxic gas sensors. In some cases nitrogen (N
2
) can be substituted for zero air when null adjusting
electrochemical sensors. Contact CETCI for clarifi cation.
Every LPT-P transmitter is calibrated in a chamber by true diff usion method prior to leaving
our facility. This method more closely emulates actual “real world” conditions. Field calibration
using gas cylinder, regulator and hose directing span gas into the sensor may result in slightly
higher readings. It is important to note that the type of gas mixture, how old the gas is and what
temperature it has been stored at will also aff ect repeatability during fi eld calibration.
NOTE:
Catalytic sensors require oxygen to work and thus the user MUST fl ow clean air or Oxygen to
obtain a true zero and the span gas must have “air” balance, not N
2
balance.
7.1.2 Regulators & Flow
Calibration gases that are lighter than or the same weight as air (CO, O
2
, etc.) should be fl owed at
0.5 LPM. Gases heavier than air (NO
2
, etc.) should be fl owed between 0.5 and 1.0 LPM. Fixed fl ow
regulators provide more accuracy.
7.1.3 Adapters
The proper calibration adapter should be utilized to allow the gas to properly diff use around the
sensor. The calibration adapter plug for an LPT-B with an internal sensor without a splash guard is
part number
CET-7000-CAP
. For an LPT-B with a splash guard, you will need to use the Cal Clip,
part number
CET-SGC
.