GE b30, Technical Reference Manual

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Functional description
8-7
Document no. 2044677-001
Nafion
TM
tube
1)
A Nafion tube is used between the water trap and the zero valve to balance the sample gas
humidity with that of ambient air. The tube prevents errors caused by the effect of water vapor
on gas partial pressure when humid gases are measured after calibration with dry gases.
Gas analyzers
After the zero valve and Nafion tube, the gas passes through the miniC measuring unit.
Sample flow differential pressure transducer
The sample flow differential pressure transducer measures pressure drop across a restrictor
and calculates the sample flow from the pressure difference.
Working pressure transducer
The working pressure transducer measures differential pressure between the tubing and
ambient air near the miniC measuring unit.
Atmospheric pressure transducer
The atmospheric pressure transducer measures real-time atmospheric pressure. The following
messages are based on the obtained pressure values: ‘sample line blocked’, ‘check D-fend’,
‘replace D-fend’ and ‘check sample gas outlet’.
Sampling pump and damping chamber
The gas sampling pump is a membrane pump run by a DC-motor. Sample flow is measured
with a differential pressure transducer across a known restriction. The motor is automatically
controlled to maintain a constant flow even when the D-fend water trap ages and starts to get
occluded. It also enables the use of sample tubes with varying lengths and diameters.
NOTE: In no occasion is the flow reversed towards the patient.
1 1) Nafion is a trademark of Perma Pure Inc.