DH Instruments E-DWT-H, Руководство по эксплуатации и обслуживанию

Страница: 68 / 126

E-DWT-H OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 58
2. P
u,0
: The absolute pressure reading of the Q-RPT, with no AutoZ offset, at the time
[AutoZ] is pressed.
3. P
offset,G
: The difference between the reading of the Q-RPT with no AutoZ offset when
[AutoZ] is pressed ( P
u,0
), and zero gauge pressure (atmospheric gauge pressure) ( P
std,0
):
P
offset,G
= P
u,0
- P
std,0
4. Δ P
atm
: The difference between atmospheric pressure (absolute) as measured by the
RPM4-E-DWT’s on-board barometer when [AutoZ] was last pressed and the current
measured value. Δ P
atm
is used to compensate real time for the evolution of atmospheric
pressure between updates of P
offset,G
by [AutoZ] . Δ P
atm
is dependent only upon the ability of
the barometer to measure small changes in atmospheric pressure over short time periods,
not upon the barometer’s absolute accuracy or long term stability.
The gauge pressure measured by the RPM4-E-DWT Q-RPT at any given moment is:
P
gauge
= P
u
- P
offset.G
- Δ P
atm
The AutoZ function can be turned ON and OFF. When the AutoZ function is OFF, the
[AutoZ] function to rezero the RPT is no longer available and dynamic compensation for
changes in atmospheric pressure using the RPM4-E-DWT’s on-board barometer is no longer
active. AutoZ should be left on at all times unless the RPM4-E-DWT’s on-board barometer is
inoperable.
 OPERATION
Note
•
The AutoZ function and values are Q-RPT specific.
•
To RUN the AutoZ routine that rezeroes the Q-RPT, use [AutoZ] (see
Section 3.7.10).
To access the RPM4-E-DWT AutoZ function press [SPECIAL] , <1AutoZ> . The display is:
1. Active Q-RPT designator.
2. Indication of active measurement mode (always <gage> for
gauge in this RPM4-E-DWT model)
3. Indication of whether AutoZ is currently ON or OFF for this
Q-RPT.
1off 2view Hi
3edit gage ON
Select <1off> (or <1on> ) to change the AutoZ status for the current Q-RPT and
measurement mode from ON to OFF or vice versa.
Note
AutoZ ON is indicated by a <z> in the MAIN RUN screen, top line, third
character from the right. When AutoZ is OFF, the character is blank.
AutoZ should always be left ON in RPM4-E-DWT unless the on-board
barometer becomes inoperable.
Select <2view> to view the current value of P
offset
for the active Q-RPT.
Note
The value of P
offset
is always displayed and entered in Pascal (Pa). P
offset
should be roughly equal to atmospheric pressure.
Select <3edit> to edit the value of P
offset
for the active Q-RPT and measurement mode.
Edit P
offset
as desired and press [ENT] to activate the new value. Press [ESC] to abandon
changes.