Yokogawa EJX930A - Manual (Page 58)

<4. Diagnostics>
4-8
IM 01C25R02-01E
NOTE
• Ref fDP must be larger than the specified
level shown in Table 4.4 (refer to subsection
4.2.2.6). No blockage can be detected when
Ref fDP is not large enough.
• The plausibility of blockage detection needs
to be confirmed by blockage simulation test.
The simulation test can be performed by
the appropriate manifold operation (refer to
subsection 4.2.2.8).
4.2.2.2 Combination of Reference Result
and Blockage Detection
 Diag Applicable
An EJX multivariable transmitter can detect four
modes of impulse line blockage: both-sides, high-
pressure side, low-pressure side, and/or single-side
and abnormal fluctuation when all the reference
values are properly measured. However, the
detectable alarm mode combination is limited when
some of the reference values are invalid. Available
Blockage Detection are shown in the below figure.
Ref fDP: OK
Ref fSPI: OK
Ref fSPh: OK
Ref BlkF: OK
Fluctuation Parameters
• Test for low-pressure side
• Test for high-pressure side
• Test for both-pressure sides
Simulation Test
• B Blocking detection
(by using Ratio fDP)
• L Side Blocking detection
(by using Ratio fSPI)
• H Side Blocking detection
(by using Ratio fSPh)
• H/L Side Blocking detection
(by using BlkF)
Ref fDP: OK
Ref fSPI: OK
Ref fSPh: OK
Ref BlkF: NG
• Test for low-pressure side
• Test for high-pressure side
• Test for both-pressure sides
• A/B Blocking detection
(by using Ratio fDP)
• L Side Blocking detection
(by using Ratio fSPl)
• H Side Blocking detection
(by using Ratio fSPh)
Ref fDP: OK
Ref fSPI: NG
Ref fSPh: OK
Ref BlkF: NG
• Test for high-pressure side
• A Blocking detection
(by using Ratio fDP)
• H Side Blocking detection
(by using Ratio fSPh)
Ref fDP: OK
Ref fSPI: NG
Ref fSPh: NG
Ref BlkF: NG
• Test for both-pressure sides
• B Blocking detection
(by using Ratio fDP)
Available Blockage Detection
[Differential pressure measurement]
[Gauge/absolute pressure and level measurement]
Ref fDP: OK
Fluctuation Parameters Simulation Test
• Test for high-pressure side
• B Blocking detection
(by using Ratio fDP)
Available Blockage Detection
F0405.ai