biosystems PhD Lite, Справочное руководство

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While in Technician mode the MODE button may be
used to scroll through the current gas level, peak
readings, STEL, TWA, AVG and information screens.
2.3.4.1 STEL
The STEL (Short Term Exposure Limit) for a particular
toxic gas is the maximum average concentration to
which an unprotected worker may be exposed in any 15
minute interval during the day. The STEL value
displayed by the PhD Lite is the average concentration
for the most recently completed 15 minutes of operation.
Note: For the first 15 minutes after the PhD Lite is
initially turned on the STEL reading is a projected
value. The PhD Lite will begin projecting a STEL
value after the first 30 seconds of operation. For the
first 30 seconds the STEL screen will show an "X"
where the reading should be.
The STEL reading is continuously updated. Audible and
visible alarms will be activated immediately any time the
most recent 15-minute average exceeds the STEL
alarm set point.
STEL CO H
2
S
0 0
STEL screen in Technician Mode:
Appendix A discusses Permissible Exposure Limit
alarm calculations in greater detail.
2.3.4.2 TWA readings
Time Weighted Average or TWA values are calculated
by taking the sum of exposure to a particular toxic gas in
the current operating session in terms of parts-per-
million-hours and dividing by an eight-hour period.
TWA CO H
2
S
0 0
TWA screen in Technician Mode:
Note: It is not possible to calculate a toxic gas TWA
reading until the PhD Lite has been operating for 15
minutes. For the first 15 minutes after start-up, the
TWA screen will show an “X” in place of the
calculation. After 15 minutes, the TWA calculation
will be shown.
Appendix A discusses Permissible Exposure Limit
alarm calculations in greater detail.
2.3.4.3 Average readings
The average readings displayed by the PhD Lite are the
simple arithmetic averages registered by the instrument
during the current operating session.
AVERAGE O
2
LEL
20.9 0
Average readings screen for O
2
and LEL in Technician
Mode.
2.3.5 Changing operating modes
To change operating mode:
1. Press the MODE button until the information
screen is displayed.
01:15 15:08
3.9V 71F
MENU
2. Hold down the left arrow key until EXIT appears and
is highlighted (approximately three seconds).
01:15 15:08
EXIT
3.9V 71F
MENU
3. Press the down navigation arrow once to highlight
MENU and press the MODE button to enter the
Main Menu.
01:15 15:08
EXIT
3.9V 71F
MENU
ALARMS CALIBRATION
OPTIONS SCREEN
VIEW TIME
EXIT
4. Use the navigation arrows to highlight OPTIONS
and press the MODE button to enter the Options
Menu.
ALARMS CALIBRATION
OPTIONS SCREEN
VIEW TIME
DISPLAY EXIT
USER_MODE SEC_BEEP
PASSCODE LANGUAGE
DECIMAL T_UNITS
EXIT
5. Once in the Options Menu, use the navigation
arrows to highlight USER MODE and press the
MODE button. The up and down navigation arrows
may then be used to toggle between operating
modes.
USER_MODE
SEC_BEEP
PASSCODE LANGUAGE
DECIMAL T_UNITS
EXIT
Operating Mode
Text Only
EXIT
↑↓
Operating Mode
Basic
EXIT
↑↓
Operating Mode
Basic/Peak
EXIT
↑↓
Operating Mode
Technician
EXIT
6. Once the preferred operating mode is shown,
confirm the selection by pressing the MODE button.