Pneumatic Positioner
YT-1200 series
Product Manual
Ver. 1.18
43
7
Maintenance
7.1
Pilot valve
1)
If Supply air pressure is not stable or Supply air is not clean, the positioner may not function
properly. Air quality and pressure should be checked regularly to see if the air is clean and pressure
set is normal.
2)
If the pilot valve has to be removed from the unit, be cautious not to lose the O-ring attached to
rear side of the pilot valve and the stabilizing spring between the pilot valve and the torque motor.
3)
On the back of the Auto Manual switch, there is a fixed orifice (0.3 pie) which could be clogged
with dusts and other substances and lead to malfunction of the positioner. First of all, remove the
pilot valve from the positioner and see if the holes on the screens are not clogged. If the screens
are clean and the positioner is not functioning, remove the Auto-Manual switch and check the back
of the switch and see if the orifice is clean. Clean the orifice with air and reassemble the switch
and the pilot valve to the positioner and test once again. If the unit is still not working, use a 0.2 pie
drill or pin and insert into the orifice hole at the back of the Auto-Manual switch.
Fig. 8-1: Pilot unit and Auto manual switch
7.2
Seals
Once a year, it is recommend to check if there are any damaged parts of the positioner. If there are
damaged rubber parts such as diaphragms, o-rings and, packings, replace with new ones.
