Yokogawa EJA440E - Manual (Page 51)

<4. Diagnostics>
4-4
IM 01C25T01-06EN
 Pressure Measurement
• Operational pressure is near outside of
diagnostic range.
• Even though pressure is constant, the flow
decreases than that under normal condition.
• A source of pressure fluctuation (pump,
compressor, blower, etc.) is shut down. As
a result, the pressure fluctuation amplitude
decreases.
 Level Measurement
• A transmitter is used to measure tank level and
the flow of fluid into or out of the tank comes to
a stop.
• The agitator in the tank is shut down.
• A source of pressure variation (a compressor,
etc.) that controls the internal pressure of a
sealed (closed) tank is shut down.
Before taking action in response to a blockage
alarm, consider the plant operating conditions.