Meriam M1 – Series Digital Manometer - Manual (Page 11)

M1 Series - DM Instruction Manual 9R000034-IR
E.O. 6409 JAN 2008
www.meriam.com
Page 11 of 17
SPAN
First, before the M1 can be spanned, it must 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 of the original
factory calibrated span pressure.
For example, given:
Accuracy = 0.25% FS, FS = 100 PSI, and Span = 70 PSI
the Measured Span must be within ±1.25 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
1.25% of the original factory span calibration pressure.
This can create a 1.25% 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.