Basic Operation - Extech Instruments HD750 User Manual

Basic Operation
Meter Power
The HD750 uses a 9V battery for power. If the meter does not switch on when the POWER
button is pressed or if the display shows BAT, replace the battery.
When the POWER buttons is pressed, the meter performs a short self‐test and reverts to the
settings in place when the meter was last turned off.
Automatic Power‐off Feature
In order to conserve battery life, the meter has an automatic power off feature (after 20
minutes). To defeat this feature, press and hold the HOLD button while turning the meter on.
Release the HOLD button when 'n' appears on the display. The meter will now remain on until
the user turns it off or until the battery weakens. Note that the Auto Power OFF feature will be
reactivated the next time the meter is turned off and then on.
Unit of Measure
Press the UNIT button to select the unit of measure. This meter offers eleven (11) units of
measure as listed below.
Fittings Connection
Connect tubing to the P1, P2 (or both) input port(s). If both inputs are used (differential mode),
the meter displays a positive pressure reading if the P1 pressure is greater than P2 and a
negative reading if P2 is greater than P1.
Unit of Measure
Pounds per square inch
Inches of Mercury
Milli‐bar
Millimeters of Mercury
Kilo‐Pascals
Kilograms per centimeter squared
Inches of water
Feet of water
Centimeters of water
Bars
Ounces per square inch
Display icon
psi
inHg
mbar
mmHg
kPa
2
Kgcm
inH O
2
ftH O
2
cmH O
2
Bar
2
ozin
4
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