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RPM4™ OPERATION AND MAINTENANCE MANUAL
© 2004-2007 DH Instruments, a Fluke Company Page 74
OPERATION
RPM4’s that have only G100K or G200K Q-RPTs (no Axxx, G15K or BG15K)
are NOT equipped with an on-board barometer.
To view the current reading of the on-board barometer press [SPECIAL],
<7internal>, <1baro>. The display is in the active pressure unit of measure
(see Section 3.3.2). The display resolution is fixed to 0.01 Pa, or its equivalent.
3.5.7.2 <2READRT>
PURPOSE
To turn ON and OFF RPM4’s automated, rate of change dependent, reading
integration rate feature.
PRINCIPLE
To obtain maximum resolution from RPM4 Q-RPT pressure measurements, an
integration time of about 1.2 second per reading is used. In most situations,
maximum precision is needed when pressures are stable so a relatively slow
display update rate presents no disadvantage. However, when pressure is
changing quickly, more rapid pressure updates are usually more important than
obtaining maximum precision on individual readings. The RPM4 read rate
function automatically adjusts pressure measurement integration time depending
on the rate of change of pressure. When pressure is changing rapidly, reading
rate is increased. When pressure is evolving slowly, reading rate is decreased
and maximum precision is obtained.
When the automated read rate function is ON, three pressure rate of change
dependent read rates are used. The result is three display update rates:
Table 10. READRT - Display Update Rates
PRESSURE
RATE OF CHANGE
DISPLAY
UPDATE
> 3 % of range span/s
≈ 0.2 s
> 0.5 and < 3 % of range span/s
≈ 0.6 s
< 0.5 % of range span/s
≈ 1.2 s
For situations in which maximum reading precision is desired regardless of pressure
rate of change, the RPM4 automated read rate function can be turned OFF.
In this case, the reading rate is always the high resolution rate of about 1.2 readings
per second.
OPERATION
To turn the automated read rate function ON or OFF or check its current status,
press [SPECIAL], <7internal>, <3ReadRt>.
The display is:
Auto read rate:
1on 2off
The cursor is on the current selection.