Troubleshooting - Fisher 3570 Instruction Manual

3570 Positioners
September 2015
D Do not remove the actuator from the valve while the valve is still pressurized.
D Disconnect any operating lines providing air pressure, electric power, or a control signal to the actuator. Be sure the
actuator cannot suddenly open or close the valve.
D Vent the power actuator loading pressure and relieve any actuator spring precompression.
D Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
D Personal injury or property damage may result from fire or explosion if natural gas is used as the supply medium and
preventive measures are not taken. Preventive measures may include, but are not limited to, one or more of the
following: Remote venting of the unit, re‐evaluating the hazardous area classification, ensuring adequate ventilation,
and the removal of any ignition sources. For information on remote venting of this positioner, refer to page 8.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.

Troubleshooting

If the positioner causes sluggish or erratic operation or the malfunctioning of the actuator, first, be certain that the
range springs, bias springs, and spring retainer are correct for the application. Consult your
Management sales office
instruction manual supplement D104021X012.
If the springs and spring retainer are correct, and careful adjustment of the unit does not produce smooth and
satisfactory operation, check the following points. Key numbers used in this procedure are shown in figure 10 except
where indicated. Figure 4 shows part locations.
1. Clean out the primary orifice on each relay by depressing the clean‐out plunger. The plunger is located in the orifice
assembly (key 29S). This operation runs a fine wire through the orifice to clear the hole.
2. Check the nozzle (key 29Q) of each relay for plugging. To clean, swing the flapper (key 12) away from the nozzle by
loosening the screw that holds the flapper in place.
CAUTION
The relays used in 3570C and 3570PC positioners use a locknut (key 29P, figure 11) on the nozzle (key 29Q, figure 11). If the
nozzle is rotated when the locknut is tight, damage to the relay diaphragm will result. Always use a wrench on the nozzle
to prevent it from turning while loosening or tightening the locknut.
Unscrew the nozzle and run a fine wire through it. Do not enlarge the hole. Also check the surface of the flapper for any
accumulation of dirt or foreign materials.
3. Check the bellows assembly for damage, misalignment, or leakage. Also check all gasketed joints for leakage. Use
soap solution for leak detection.
4. Check the beam for damage, binding or rubbing against stationary parts. Check the flexure strip screws (key 17) for
tightness.
5. If the positioner operation has improved, refer to the adjustment procedures.
6. If the relays require replacement, go to step 7.
7. Unscrew the three machine screws (key 31) from each relay and remove the relays.
22
to determine if a new range springs, bias springs, and spring retainer are required. Refer to
Instruction Manual
D200137X012
Emerson Process