Yokogawa GD40 Gas Density Detector - Manual (Page 170)

<11. INSPECTION AND MAINTENANCE>
11-1
IM 11T3E1-01E
11. INSPECTION AND MAINTENANCE
To ensure the GD402 analyzer remains highly accurate with excellent operating conditions,
routine inspection and maintenance is essential. Refer to the check items in this chapter to
determine which items to apply in your inspection and maintenance, and check them periodically.
11.1 Routine Inspection and Maintenance
11.1.1 Checking Readings and Calibrating the Analyzer
Measure the standard gases every two to three months to check the output signal (Note: the
interval varies depending on the operating conditions). If the output signal has errors, carry out
zero and span calibration. For details on calibration, see Chapter 8, 9 or 10.
11.1.2 Checking the Flowrate of Sample Gas
The sample gas should be supplied to the detector at 600 ml/min ±10%. Periodically make sure
the given flowrate is kept constant. When checking the flowrate, also make sure the piping is
normal and there is no leakage of calibration gases.
11.1.3 Periodic Replacement of the Detector's O-rings
The O-rings are made from NBR, a material that is not very susceptible to plastic deformation.
Their sealing capabilities therefore are not readily impaired. Any deterioration in these O-rings
however can result in not only gas leakage but reduced resistance to mechanical vibration,
which in turn may lead to reading errors. For this reason, it is recommended that the O-rings be
replaced at a fixed interval (every two to three years). Consult Yokogawa for the replacement of
O-rings.