FEDCO MSD-200 - Page 46

MSD
TM
Series
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- 46 -
Pump Assembly Continued
4. Without disturbing the indicator set up, return
it to its original upright position. The indica-
tor should return to zero. This veries that
no instrument drift has taken place. If instru-
ment drift has occurred, repeat the Sag Test
steps 1 through 4.
EXAMPLE: If the dial indicator registers a
reading of -0.002, Multiply the negative read-
ing by negative one half or -0.5. This will give
you a product of +0.001. Pre-setting the dial
indicator to +0.001 will compensate for the “sag
error’ during measurement procedures.
Figure 88 - Formula For Instrument Sag
Compensation
METALIC STOCK
DIAL INDICATOR RETURNS
TO ZERO SETTING
(NO INSTRUMENT DRIFT)
SAG ERROR INDICATOR READING -0.002
MULTIPLIED BY -0.5
EQUALS COMPENSATION SETTING +0.001