AO2000
CONTINUOUS GAS ANALYZERS | OI/AO2000-EN REV. B
41
Purge gas
The following is to be used as purge gas:
•
Nitrogen when measuring flammable gases and
•
Instrument air when measuring corrosive gases (quality per ISO 8573-1
Class 3, i.e. max. particle size of 40
μ
m, max. oil content 1 mg/m
3
, max.
dew point +3 °C).
NOTE
The purge gas may not contain any sample gas components! Any sample
components in the purge gas can cause false readings.
Purge gas flow rate during initial purge
The purge gas flow and the duration of the purge process depend on the
volume to be purged (see the following table). If the purge gas flow is lower
than specified, the duration of the purging must be extended accordingly.
Volume to be purged
Purge gas flow rate Duration
Gas path
100 l/h (max.)
approx. 20 s
Central unit with or without analyzer
module
200 l/h (max.)
approx. 1 h
Analyzer separately: Caldos25, Caldos27,
Magnos206, Magnos28, Magnos27
200 l/h (max.)
approx. 3 min
Purge gas flow rate during operation
Purge gas flow rate at device inlet max. 20 l/h (constant), purge gas positive
pressure: p
e
= 2 to 4 hPa.
For a purge gas flow rate at the device inlet of 20 l/h, the purge gas flow rate
at the device outlet is approx. 5 to 10 l/h.
Information for the selection and use of flowmeters:
•
Measuring range 7 to 70 l/h
•
Pressure drop < 4 hPa
•
Needle valve open
•
Recommendation: Flowmeter 7 to 70 l/h, Part Number 23151-5-8018474
ATTENTION
Purge gas can escape from the housing if there are any leak points.
When using nitrogen as the purge gas, take all required precautions
against suffocation.
The purge gas flow must always be restricted upstream of the purge gas
inlet! If the purge gas flow is not restricted until after the purge gas out-
let, the full pressure of the purge gas will affect the housing seals which
can destroy the operator panel keypad!
