24
Model EA91A＆EA90A
IMPORTANT
OUT
SUP
Set Screw
Restricuion
7.2 Maintenance Procedure
7.2.1 Restriction and Filter
The restriction of air pipe, clogging and dirt
of filter in the positioner might cause failure. Clean
the air pipe and the filter periodically.
⑴ Set supply air pressure at zero.
⑵ Loosen the drain cock of the filtered pressure
reducing valve. Then, drain and purge properly.
⑶ Remove the restriction.
⑷ Clean overall restriction by inserting a ∅0.2
mm wire into hole of restriction.
⑸ Remove the filter of nozzle base. Then, clean
and purge properly.
⑹ Apply a coating of silicon grease thinly and
uniformly when assembling.
⑺ Perform the reversed procedure for reassem
-bling. At this point, check for leakage from
restriction.
⑻ Reset the supply air pressure to original
pressure. Then, check for leakage from the
gasket and the pilot assembly.
⑼ Align the opening of the pilot cover with
original position, and mount the pilot cover.
7.2.2 Pilot
⑴ Follow the procedure described in Item 7.2.1
for operation of supply air pressure and filtered
pressure reducing valve.
⑵ For pilot assembly, loosen three pan head
screws, and remove the pilot from manifold
after removing the pilot cover.
⑶ Disassemble the pilot. Check for wear and
tear in upper and lower diaphragms, and for
presence or absence of damage in supply
air valve and seat of main body.
⑷ At the same time, check for wear and tear in
gasket A and B.
⑸ Clean the parts described above and ove-
rall pilot.
⑹ Reverse the procedures to reassemble the
pilot. At this point, make sure that the orifice
plate is placed at original position.
⑺ Reverse the procedures to mount the pilot
assembly to manifold when removing the pilot
assembly.
Never loosen the set screw on the nozzle
base when performing the restriction
check. (The gap between flapper and
nozzle is adjusted precisely.)
IMPORTANT
After checking each part, be sure to
check by performing the operating test
and the loop test.
