ABB EasyLine Series Instructions For Installation Start-Up And Operation page 35

Housing Purge during Operation
Housing Purge during Operation when Measuring Flammable Gases
Housing Purge in the Fidas24
Purge gas flow:
Positive pressure of
purging gas:
With a purge gas flow of 20 l/h at the instrument inlet, the purge gas flow
at the instrument outlet due to leakage will amount to approx. 5...10 l/h.
The housing has to be purged with nitrogen. Purge gas flow 1...20 l/h.
The purge gas flow must be monitored at the purging gas outlet.
The housing purge is implemented in the Fidas24 gas analyzer in such a
way that a part (approx. 600...700 l/h) of the instrument air is conducted
continuously through the housing as purging air. This ensures that a
flammable mixture cannot form in the housing in the event of a leak in the
combustible gas feed path.
The housing purge is always active if compressed air is switched on,
even if the instrument air valve is closed.
Preparation for Installation
max. 20 l/h (constant) at the instrument inlet
p = 2 to 4 hPa
e
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