Masoneilan 4700P/E & 4800P/E Positioners Manual | 37
© 2021 Baker Hughes Company. All rights reserved.
Zero Adjustment
See Figure 18 (page 56) and Figure 19 (page 58).
The zero adjustment is made with the zero nut (4B). When the positioner is installed and the
pneumatic circuits are connected apply low instrument signal (i.e., 3 psi for 4700P/4800P, 4 mA
for 4700E/4800E), release locknut (4C) and turn zero nut (4B) to adjust valve plug to proper
position (open or closed). Then tighten zero lock nut (4C).
NOTE
Do not attempt to adjust zero nut with signal above
low end of signal range. If valve is seated at low
end of signal range, after making zero adjustment,
decrease signal below low end of signal range and
slowly increase signal to ensure valve plug lifts off seat
at desired signal. If valve is open at low end of signal
range, adjust zero so valve indicates Open on travel
indicator scale.
Span Adjustment
See Figure 18 (page 56) and Figure 19 (page 58).
If the valve does not fully stroke for a full signal span, the feedback spring rate is too high.
Loosen screw (8) and turn spring (5) on the spring end (4) to increase the number of active coils
and decrease the spring rate. Conversely, if full stroke is reached prior to full signal span, turn
the spring to decrease the number of active coils and increase the spring rate.
Adjustment of +1/4 turn of the spring changes its rate by approxi10%.
After making a spring adjustment, it is necessary to reset the zero. This is done by turning the
zero adjustment (4B), and tightening zero locknut (4C).
Example: If the number of active coils is increased making the spring longer, it is necessary to
readjust the zero nut to compensate for the increased spring length.
When span adjustment has been completed, re-tighten the spring locking socket head screw
(8).
CAUTION
When installing positioner with cam in place, check
the position of the spring (5) on diaphragm S/A (9) to
ensure that it is centered on the diaphragm.
Summary of Contents for Masoneilan 4700P
Page 16: ...2021 Baker Hughes Company All rights reserved 16 Baker Hughes Figure 5 87 88 Actuator...
Page 30: ...2021 Baker Hughes Company All rights reserved 30 Baker Hughes Figure 12 FM Installation...
Page 32: ...2021 Baker Hughes Company All rights reserved 32 Baker Hughes Figure 14 ATEX Installation...
Page 64: ...2021 Baker Hughes Company All rights reserved 64 Baker Hughes NOTES...
