Chapter 5: Maintenance and Troubleshooting
5-9
5.4 Cleaning the Flapper
■ Introduction
If contaminants from the instrumentation air have accumulated on the flapper, clean
the flapper as described below.
Step Procedure
1 Remove the three pilot cover screws.
2 Have scraps of paper 0.2 mm thick ready. Common business cards would be suitable.
3 Use the scraps of paper to clean the contaminants that have accumulated in the gap
between the EPM nozzle and the flapper.
4 After cleaning the gap, attach the pilot cover to the main unit.
Caution
•
If air pressure is being supplied to the device then, when the flapper is cleaned, the
nozzle back pressure will change, causing the valve position to change suddenly.
Clean the flapper only under conditions that that will neither cause personal injury
nor affect plant operation even if the valve should move suddenly.
5.5 Insulation Resistance Test
Caution
•
As a rule, do not perform the insulation resistance test. Performing this test may
damage the built-in lightning arrester for surge voltage absorption. If these tests ab-
solutely must be carried out, follow the specified procedure closely.
■ Test procedure
• Detach the device's external wiring
• Connect the + and - input signal terminals, and the + and - output signal termi-
nals.
• Perform the test in between these shorted terminals and the ground terminals.
• Applied voltage and decision criteria are as follows. In order to prevent damage to
the meter, do not apply voltages higher than the values shown below.
■ Test criteria
The test criteria are as follows.
Test Criteria
Insulation resistance test 2×10
7
Ω or higher at test voltage 25VDC (25°C, 60%RH or lower)
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