Datex-Ohmeda S/5 monitors
Document No. 800 1009-1
8
2
FUNCTIONAL DESCRIPTION
2.1
Measurement principle
2.1.1
CO
2
, N
2
O, and agent measurement
TPX is a side stream gas analyzer, measuring real time concentrations of CO
2
, N
2
O and anesthetic
agents (Halothane, Enflurane, Isoflurane, Desflurane, and Sevoflurane).
Thermopile
detectors
Temp sensor
Sample
gas in
Sample
gas out
Sample
chamber
Figure 1
TPX sensor principle
Anesthetic agents or mixtures of two anesthetic agents are automatically identified and
concentrations of the identified agents are measured. TPX also detects mixtures of more than two
agents and issues an alarm.
TPX is a nondispersive infrared analyzer, measuring absorption of the gas sample at seven infrared
wavelengths, which are selected using optical narrow band filters.
The infrared radiation detectors are thermopiles.
Concentrations of CO
2
and N
2
O are calculated from absorption measured at 3-5
µ
m.