Ashcroft 1495 - Low Pressure Receiver Gauge - Manual (Page 14)

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d. Remove pointer and reassemble dial and
dial screws (finger tight).
e. Lightly press pointer onto pinion.
f. Check accuracy at full scale. If error exceeds
1% return to step 1, otherwise proceed.
g. Check accuracy at midscale. If error exceeds
1% slide dial left or right to compensate.
h. Continue at * below.
Vacuum range –
a. Using a pencil, refer to dial and mark the
0 and 25 inch of Hg positions on the case
flange.
b. Remove the dial.
c. Apply 25 inches of Hg vacuum.
d. Lightly press pointer onto pinion carefully
aligning it with the 25 inch of Hg vacuum
mark on case flange.
e. Release vacuum fully.
f. Note agreement of pointer to zero mark on
case flange.
g. If span is high or low, turn span block as
shown in Figure 5b on page 15.
h. Repeat steps 4 through 8 until span is
correct.
i. Remove the pointer.
j. With 25 inches of Hg vacuum applied,
reassemble dial, dial screws (finger tight)
and pointer.
k. Apply 15 inches of Hg vacuum and note
accuracy of indication. If required, slide dial
left or right to reduce error to 1% maximum.
l. Continue at * below.
* Now complete calibration of the gauge as
follows:
a. Firmly tighten dial screws.
b. Firmly tap pointer onto pinion, using brass
back-up tool from Ashcroft kit 1205T if
gauge has rear blow-out plug. If gauge has
top fill hole no back-up is required.
c. Recheck accuracy at zero, midscale and full
scale points (Figures 5a & 5b on page 15).
d. Reassemble window, gasket and ring.