Changing Controller Action - Emerson Fisher 4194HA Instruction Manual

Instruction Manual
D200156X012
Table 5‐1. Troubleshooting Chart (Continued)
Fault
7. Controller remains 7.5 Relay failure or
at full output. restriction in nozzle
(continued) passage.
7.6 Flapper misaligned.
8. Controller remains 8.1 Gauge not
at zero output. functioning.
8.2 Differential pressure
unit or linkage failure.
8.3 Mechanical alignment.
8.4 Relay malfunction.
8.5 Nozzle pressure leak.

Changing Controller Action

The following steps describe changing controller action from direct (increasing process differential pressure produces
increasing output pressure) to reverse (increasing process differential pressure produces decreasing output pressure)
or vice versa.
1. Loosen two screws (key 6) in the proportional band indicator cover (key 36). Do not remove the screws.
2. Lift the proportional band indicator cover as shown in figure 5‐2.
3. Rotate the proportional band knob (key 25) to the desired controller action.
4. Install the proportional band indicator cover (key 36) and tighten the two screws (key 6).
Possible Cause
7.5 Manually move flapper 1.6 mm
(1/16‐inch) from the nozzle.
7.6 Manually push the flapper away from the
nozzle. Controller output should go to 0 psig.
8.1 Verify that the supply pressure is at its
correct value and that the controller output
is zero.
8.2 Vary the process differential pressure and
observe the flapper. Inspect the sensor and
linkages for damage. Refer to the differential
pressure unit instruction manual.
8.3 Move the set point and verify that the
nozzle can be capped by the flapper. If not,
inspect linkages and flexures for damage.
8.4 With the supply pressure on, check for a
low flow of air at the nozzle output. When
capped, the output pressure should build
rapidly. The relay should open and pass a
large flow of air through the "OUTPUT"
nipple.
8.5 Check for nozzle tubing leaks with a soap
solution with the nozzle capped by the
flapper. Press on the nozzle cap gently to
ensure the nozzle O‐ring is sealing. Ensure
the relay nozzle tubing nut is tight and the
manifold screws (keys 34 and 131) are tight.
Check
7.5 If the output pressure remains at the supply
pressure, remove the controller case and cover
assembly and test again with the relay nozzle
tubing nut loose. If the output is 0 bar (0 psig),
clean or replace the nozzle assembly. If the
output remains at supply pressure, replace the
relay.
7.6 Perform the flapper alignment procedure.
8.1 Replace gauges as necessary.
8.2 Repair or replace parts as necessary.
8.3 Repair or replace parts as necessary.
8.4 Press the cleanout wire on the relay. If the
problem persists, replace the relay.
8.5 Tighten the relay nozzle tubing nut, tighten
manifold screws (keys 34 and 131), or replace
nozzle assembly O‐ring or set point beam
assembly as appropriate.
4194HA, HB, HC Controllers
July 2018
Correction
41