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

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3. OPERATION
Page 27 © 2009 DH Instruments, a Fluke Company
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Caution
Opening the reservoir shut off valve while the E-DWT-H is under pressure
will very rapidly drop the pressure. Generally, it is not recommended to
drop the pressure applied to pressure measuring devices very rapidly. To
reduce pressure slowly, use the variable volume and only open the
reservoir shut off valve to open the system to atmosphere.
3.5.3 Pressure Fine Adjustment, Fine Adjust Valve
To adjust pressure more precisely than is possible with the variable volume, the fine adjust
valve is used. When the valve is open, the displacement of its needle is used as a miniature
variable volume to adjust pressure.
The test isolation and fine adjust valve is a needle valve with a stroke of several millimeters.
Turn the valve handle CW to increase pressure CCW to decrease.
When using the fine adjust valve to adjust pressure, be sure not to close the valve so that the
E-DWT-H is no longer connected to the test system. If turning the valve handle or the
variable volume does not change the pressure indicated by both the RPM4-E-DWT and the
device under test, the valve is closed.
3.6 RPM4-E-DWT User Interface
The E-DWT-H’s RPM4-E-DWT reference pressure monitor is designed to offer the optimum balance
between simple, straight forward operation and the availability of a wide variety of functions with a high
level of operator discretion if desired.
The RPM4-E-DWT’s local operator interface is through the front panel’s 2 x 20 character alpha-numeric
display, a function/data keypad, a cursor control pad and a
Ready/Not Ready
indicator. An optional
[ENTER] footswitch is available. Remote communication is also available via the RS-232 (COM1)
interface (see Section 4).
The E-DWT-H mounts the RPM4-E-DWT at a convenient viewing angle. If the RPM4-E-DWT has two
Q-RPTs, the E-DWT-H includes a valve and visual indicators to isolate and protect the RPM4-E-DWT’s
Lo Q-RPT when using the Hi Q-RPT (see Section 3.4).
3.6.1 MAIN RUN Screen
The RPM4-E-DWT MAIN RUN screen is its home display that is reached on power-up and
from which other functions and menus are accessed. It is the very top level of all menu
structures.
The MAIN RUN screen is where RPM4-E-DWT is left in normal operation. It displays the
current measured pressure as well as a variety of additional information if desired.
Figure 13 and its legend summarize the RPM4-E-DWT MAIN RUN screen fields and their
functions.
Note
RPM4-E-DWT has a screen saver function which causes the display to dim
if no key is pressed for 10 minutes. Pressing a key restores full power to
the display. The screen saver time can be changed or screen saving can
be completely suppressed (see Section 3.9.5.1).