Dwyer instruments, inc – Dwyer AQH-20 User Manual

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When desired value is reached, press the button to save the value and
return to the main menu or press button to return to main menu without
saving the changes.

If the alarm sounds, simply press any key (but power key) to silence the alarm.

Changing Engineering Units
Hold down for more than one second during normal mode to reach the main
menu.

Press the or the to toggle between alarm setup and unit setup.

When “Units” and “P3.0” are displayed on the LCD, press the button to
enter engineering unit setup.

The current temperature unit will be blinking on the lower left of the display. Press
the or the to toggle between Celsius and Fahrenheit.

When desired unit is set, press the button to save and return to the main
menu or press button to return to the main menu without saving the changes.

Holding the Current Value
Press and release the to freeze the primary temperature display. “HOLD”
will appear at the top left of the screen.

In order to return to normal operation, press the button again and the “HOLD”
icon disappears from the display.

Max, Min, and Average Data Functions
Press the button to cycle through the MIN, MAX, STEL, and TWA functions.
To exit, cycle through until none of the four mentioned functions appear on the
screen.

MIN and MAX readings show the minimum and maximum CO

readings on the

main display, respectively. STEL and TWA readings show the weighted average of
the CO

readings on the main display. STEL uses all the CO

readings from the

past 15 minutes to calculate the average. TWA uses all the readings from the past
8 hours to calculate the average. The current temperature and humidity continues
to be displayed at the bottom of the LCD.

Automatic Power Off (Sleep Mode)
The instrument will shut off automatically after 20 minutes of operation to conserve
battery life if no button is pressed. To disable the sleep mode, press “Ø set” and the
“HOLD” buttons simultaneously before power on. An “n” icon will appear in the
center of the display once disabled.

BATTERY REPLACEMENT
The Air Quality Handheld displays as a visual low battery indication.

When “Lob” appears on the LCD and a beeper sounds, the batteries must be
replaced.

To Replace the Battery:

1. Make sure the unit is powered off.
2. Lay face down on a clean, flat surface.
3. Open battery compartment by pushing in tab and lifting cover.
4. Replace battery, taking note of the indicated polarity.
5. Replace the cover.

Calibration

The CO

sensor should be calibrated in fresh outdoor air that is well ventilated and

in good weather conditions. Do not calibrate in areas with high CO

concentrations

such as crowded areas.

Procedure:
1. Place meter in the calibration site.
2. Turn the unit on and hold down and simultaneously to enter CO

calibration mode.
3. “400ppm” and “CAL” should be blinking on the display.
4. Wait 10 minutes until the blinking stops and the unit returns to normal mode.

To abort the calibration, turn the meter off at any time.

RH Calibration

The RH must be calibrated with the default calibration salt. If not done properly and
with the correct salts, it will cause permanent damage.

33% Calibration Procedure:
1. Plug sensor probe into 33% salt bottle.
2. Hold down and under normal mode to enter 33% calibration.
3. “CAL” and the calibrating value should be blinking on the LCD with current
temperature displayed but not blinking.
4. Wait about 60 minutes until “CAL” and the calibrating value stop blinking.

75% Calibration Procedure:
1. After 33% calibration, plug the sensor probe into 75% salt bottle.
2. Press the button to enter 75% calibration mode.
3. “CAL” and the calibrating value should be blinking on the LCD with current
temperature displayed but not blinking.
4. Wait about 60 minutes until “CAL” and the calibrating value stop blinking and the
meter returns to normal mode.

Users can also calibrate either calibration point individually. For the 33% calibration
point, press the once the 33% calibration is complete. For the 75%
calibration point, press the or within the first five minutes while
initializing the 33% calibration.

MAINTENANCE
A periodic check of the system calibration is recommended. Model AQH-20 is not
field serviceable and should be returned if repair is needed (field repair should not
be attempted and may void warranty). Be sure to include a brief description of the
problem plus any relevant application notes. Contact customer service to receive a
return goods authorization number before shipping.

DWYER INSTRUMENTS, INC.

Phone: 219/879-8000

www.dwyer-inst.com

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Fax: 219/872-9057

e-mail: [email protected]

Printed in U.S.A. 8/13

FR# R6-443744-00 Rev.2

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CAL

Esc

CAL

Esc

CAL

Esc

DP/WBT

MODE

DP/WBT

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CAL

Esc

MODE

HOLD

CAL

Esc

HOLD

The RH calibration should be done at 25ºC and humidity close
to the calibration salt being used (must at least be stable).

NOTICE

Model AQH-20 requires at least 5 minutes worth of values in
order to calculate either of the CO

averages.

NOTICE

If the unit fails to power on, it is likely that the batteries also need
to be replaced.

NOTICE

Failing to turn the handheld off may result in malfunction of the
unit. Dispose of used batteries promptly and keep away from

children.

NOTICE

M /AV