Meriam M2 – Series Smart Manometer - Manual (Page 39)

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Appendix 2: M200-DI Application Notes
Zeroing for Position Sensitivity
M200-DI (wet/wet) units have liquid filled, sealed sensor
assemblies. The fill fluid will apply hydrostatic head pressure to the
DP sensor in uniform ways depending on the orientation of the
handheld during measurement sessions.
Horizontal plane (yaw axis): No zero offset
Vertical plane (pitch axis): No zero offset
Roll axis: Zero offset occurs. When the unit is rotated about its roll
axis in the horizontal plane or any less-than-vertical plane, the fill
fluid in the highest side imparts a greater hydrostatic pressure to
the DP sensor. The result is a zero offset in either the + or
–
direction depending on the roll direction.
Zeroing: with no pressure applied to either the P1 or P2 ports,
place the unit in the orientation it will be used in when making
measurements. Then use the Zero function keys to null out the
position effect on zero. Measurement stability is excellent at any
fixed position.
M200-DI0001 and M200-DI0005 ranges: These ranges are most
sensitive to roll axis position because the affect is a greater
percentage of full scale range than in higher ranges. Small
changes in position about the roll axis will register on the display
as significant pressure changes. Therefore these two ranges will
need to be held still while taking measurements or they may need
to be placed on a bench or other stationary support prior to making
measurements.
Zeroing for Static Pressure Effect on Zero
M200-DI models are available in measurement ranges from 1
to 500 PSID for common mode static pressures up to 1000
PSID. The zero reading on these units is linearly offset by the
static pressure of the service. This offset is easily zeroed out
using the zero function. Meriam recommends applying normal
static pressure to the subject DI model using a 3-valve
equalizing manifold to properly pressurize the M200-DI. The
DI model should be zeroed under normal static pressure
conditions, with the equalizing valve open (common mode
pressure on P1 and P2 ports), to assure proper zeroing.