Ametek PMT 40, Manual

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User Manual
16
MEASURING ELEMENT
All bourdon tube and metal diaphragm elements
are interchangeable.
CALIBRATION AND TRACKING
INSTRUCTIONS FOR ALL ELEMENTS
All measuring elements are calibrated using the
same adjustments on the indicating movement.
To make these adjustments, the dial must be
removed. The dial can be removed without
removing the pointers, by aligning the red and
black pointers with one another by using the
set knob, loosening the two dial screws, and
manipulating the elliptical center hole over the
pointers.
Calibration of Element is Made as Follows
(Fig. 16):
1. Select three pressures at or near; the lower
end, the center and the upper end of the dial
range. For future reference, these will be
known as valves Po, Pc and Pu.
2. Disconnect the control link (closet to chassis)
at its upper end. Spring the retainer clip
open just enough to disengage the ball from
bearing hole.
3. Apply Po (lower end of range) to the element
and note black pointer reading. If it does not
read correctly, hold the hex hub of the pointer
with 0.25” wrench and turn pointer to proper
value. CAUTION: Apply torque near center of
pointer to avoid bending it.
4. Apply Pu (upper value of scale) to element.
Note pointer reading. If pointer reads too
high, dimension C must be increased. If
the pointer reads too low, dimension C
must be decreased. Remove dial and make
adjustments as follows:
a. To increase C: loosen lock screw ¼
turn and turn range adjust hex forward.
For each percent of error, hex should
be turned about ¼ turn. Make proper
adjustment. Tighten lock screw.
b. To decrease C: loosen lock screw ¼ turn
and turn range adjust hex back ¼ turn for
each percent of error. Tighten lock screw.
5. Replace dial, and apply Po. Reset black
pointer to proper reading, apply Pu and
note reading, apply Pu and note reading.
Make adjustments as described in 4 above.
Continue adjusting and testing as per 4 and 5
until pointer reads correctly at Po and Pu.
6. With dial in place, apply Pc (at center of
range) to the element. If pointer reads low,
link dimension L must be increased. If
pointer reads high, L must be decreased.
Remove dial and make adjustments as
follows:
a. Loosen link screw and lengthen or shorten
link as required. Note resulting black
pointer movement. For each percent of
error at Pc move black pointer about 90°.
BELL CRANK
BELL CRANK
DIAPHRAGM LINK ASSY.
ANGLE
OVERPRESSURE STOP SCREW
SLACK DIAGHRAM
BELL CRANK
RED POINTER
ELEMENT MTG. SCREW (3)
DIAL SCREW (2)
SHOULDER CREW
SET POINT LINK
CONTROL LINK
TRACKING ADJ.
DIAL
BIAS SPRING
RANGE SPRING
BLACK POINTER
Figure 20