L1 /
7
CH3041
NON-DISPERSIVE IR
Non Dispersive Infra-Red (ND-IR)
• A light
source is shone on a sample cell containing
the gas to be measured (here CO) &
a reference cell (no CO) at the same time.
•The light, less any absorption, travels
through to two detector
cells separated by a
diaphragm.
through to two detector
cells separated by a
diaphragm.
• The difference in
heating
in the cells causes the
diaphragm to move which
generates a signal » [CO]
in the cells causes the
diaphragm to move which
generates a signal » [CO]
• eg. CO IDL 0.6 ppm.
IDL = Instrument Detection Limit
IDL = Instrument Detection Limit
