Meriam M1 – Series Pressure Calibrator - Manual (Page 12)

M1 Series – PC Instruction Manual 9R000035-IR
E.O. 6409 JAN 2008
www.meriam.com
Page 12 of 18
SPAN
First, before the M1 can be spanned, it must first be zeroed.
Second, to Span the M1, a calibration specific pressure must be applied. If this
Span pressure is known (because the unit has been spanned previously), skip
the next step.
To determine the Span pressure, make sure the pressure sources are still
vented (i.e. still at zero), then press and hold the O and B keys until “F.CAL”
is displayed. Immediately following “F.CAL” is the value of the pressure that
should be applied. The red backlight will flash to indicate the M1 was not
spanned (since there was no pressure applied).
Third, apply the Span pressure to the M1 and let the pressure stabilize. Then
press and hold the O and B keys until “F.CAL” is displayed. Immediately
following “F.CAL” is the value of the pressure that should be applied. The
display will read “----” during the spanning process. The process is complete
when the display changes from “----” to the Span pressure reading.
Note: The M1 can only be spanned if the calculated measured span is within
5 times full scale accuracy term of the original factory calibrated span
pressure
For example, given:
Accuracy = 0.1% FS, FS = 100 PSI, and Span = 70 PSI the Measured
Span must be within ±0.5 PSI of 70 PSI
Note: It should be noted that if the span pressure source used to recalibrate
any pressure instrument is not accurate, the M1 span can be
recalibrated to a maximum discrepancy of 0.5% of the original
factory span calibration pressure. This can create a 0.5% gain error in
all pressure measurements after the recalibration of span.
If this procedure generates a new value outside this limit, the red
backlight will flash to indicate the procedure failed and the previous
value was retained.
Restore Factory Defaults
The factory calibration defaults can be restored in the M1 by simultaneously
pressing the O and F and U keys until the display shows “----”. The process
is complete when the display changes from “----” to the current pressure
reading.