Extech Instruments HD750 User manual

User Guide
Heavy Duty
Differential Pressure Manometer
Model HD750

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Warranty
EXTECH INSTRUMENTS CORPORATION (A FLIR COMPANY) warrants this instrument
to be free of defects in parts and workmanship for three years from date of shipment (a six
month limited warranty applies to sensors and cables). If it should become necessary to
return the instrument for service during or beyond the warranty period, contact the
Customer Service Department at [phone] ext. 210 for authorization or visit our
website www.extech.com for contact information. A Return Authorization (RA) number
must be issued before any product is returned to Extech. The sender is responsible for
shipping charges, freight, insurance and proper packaging to prevent damage in transit.
This warranty does not apply to defects resulting from action of the user such as misuse,
improper wiring, operation outside of specification, improper maintenance or repair, or
unauthorized modification. Extech specifically disclaims any implied warranties or
merchantability or fitness for a specific purpose and will not be liable for any direct, indirect,
incidental or consequential damages. Extech's total liability is limited to repair or
replacement of the product. The warranty set forth above is inclusive and no other
warranty, whether written or oral, is expressed or implied.
Introduction
Congratulations on your purchase of the Extech Manometer Model HD750.
This device measures gauge and differential pressure in the range of ±5.000 psi. The
HD750 offers eleven (11) units of measure (user selectable by front panel pushbutton) and
has a differential input that uses convenient quick-disconnect fittings.
Advanced features include DATA HOLD, MIN-MAX-AVG RECORD mode,
ZERO/OFFSET, AUTO POWER OFF, and USB PC interface.
This instrument is shipped fully tested and calibrated and, with proper use, will provide
years of reliable service.

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Meter Description
1. P2 input
2. AC adaptor jack
3. P1 Input
4. LCD Display – Indicates the measurement data, unit of
measure, elapsed timer, and function symbols as
described in this manual
5. USB PC interface jack (3.5mm) – For use with data
acquisition software
6. UNIT button – Press to select the unit of measure
7. DIF button– Press to display differential pressure. Also
used to OFFSET the displayed readings.
8. RECORD button– Press to access the MIN/MAX/AVG
recording mode
9. HOLD / ZERO button– Press to freeze the displayed
reading. Also used to zero the display (press and hold
until display shows all zeroes).
10. BACKLIGHT button – Press to switch the display
backlight ON. The backlight will automatically turn OFF after 40 seconds.
11. POWER button – Press to turn the meter ON or OFF
12. Battery compartment (on rear)
Display
1. USB data output active
2. Differential Pressure Mode
3. Data Hold Mode
4. Primary display
5. Record Mode
6. MAX/MIN/AVG indicators
7. Low Battery Indicator
8. Pressure unit of measure
9. Elapsed Timer

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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.
Unit of Measure Display icon
Pounds per square inch psi
Inches of Mercury inHg
Milli-bar mbar
Millimeters of Mercury mmHg
Kilo-Pascals kPa
Kilograms per centimeter squared Kgcm2
Inches of water inH2O
Feet of water ftH2O
Centimeters of water cmH2O
Bars Bar
Ounces per square inch ozin2
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.
Zero Adjust and Offset function
To ZERO the meter: Before use and without fittings attached to the meter, press and hold
the HOLD button for 3 seconds or until the display shows all zeroes.
To OFFSET meter readings: Press the DIF button while taking a measurement.
Subsequent readings will represent the difference between the current measurement and
the measurement that was on the display when the DIF button was pressed.

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MIN-MAX-AVG Record Mode with Elapsed Timer
The RECORD function tracks the maximum (MAX), minimum (MIN), and average (AVG)
readings with a time stamp. The elapsed timer is displayed on the lower right-hand corner
of the LCD and informs the user of the time a MAX or MIN reading was recorded.
1. Press the RECORD button once. The REC indicator will appear on the display and
the displayed elapsed timer will start (HH:MM:SS format [hours:minutes:seconds]).
2. Press the RECORD button again to view the highest (MAX) reading recorded since
the RECORD button was first pressed. The MAX indicator and maximum reading will
appear on the display. The elapsed timer will show the time of the MAX event.
3. Press the RECORD button again, the MIN indicator and the minimum value will
appear on the display. The elapsed timer will show the time of the MIN event.
4. Press the RECORD button again, the AVG indicator and the average value will
appear on the display. The elapsed timer will continue to run.
5. To return to normal operation, press and hold the RECORD button until the display
indicators REC, MAX, etc. switch off.
Note that in the RECORD mode, the backlight and the power buttons are the only
available functions.
USB PC Interface
The meter has a built-in USB port for use with the Manometer Data Acquisition software.
The software allows the user to view, save, export, and print readings from the HD750.
Refer to the documentation included with the software for complete details.
Displayed Error Codes
The following codes are displayed when the meter encounters an error.
ERR 1: Pressure input exceeds specified limits
ERR 2: Pressure input is too low to read
ERR 3: The Differential Pressure input exceeds specified limits
ERR 4: The Differential Pressure input is too low to read

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Specifications
General Specifications
Display Four digit LCD with function indicators
Units of Measure BAR, mBAR, psi, kg/cm2, mm Hg, inches Hg, kPa, feet H2O,
inches H2O, cm H2O, and oz in2
Accuracy ±0.3%FS (@ 25°C)
Repeatability ±0.2% to 0.5% FS
Linearity/Hysteresis ±0.3%FS
Combined Accuracy ±1.1%FS
Maximum Pressure 10psi
Response time 0.5s typical
Input circuit Differential inputs (P1 and P2)
Input Ports Two metal 4.8mm, barbed for 1/8" (3.17mm) ID tubing
Data Hold Freezes displayed reading
Sensor Built-in piezoelectric sensors
Zero / Offset function Pushbutton activation
Sample rate 0.5 sec. (approx.)
Compatibility Air or non-corrosive and non-ionized gas (not intended for
use with liquids)
Auto Power OFF Meter turns off after approx. 20 minutes to conserve energy
(can be deactivated)
PC Interface Built-in USB serial interface
Storage conditions 14 to 140oF (0 to 60oC); < 80% RH
Operating conditions 32 to 122oF (0 to 50oC); < 80% RH
Battery power 9V alkaline battery (BAT low battery indicator)
Battery life 125 hours typical
Dimensions 8.2 x 2.9 x 1.9” (210 x 75 x 50mm)
Weight 9.8oz (280g)
Range Specifications
Range/Units (Max.) Resolution
± 0.344bar 0.001
± 344.7mbar 0.1
± 5.000psi 0.001
± 0.351Kg/cm20.001
± 258.5 mm Hg 0.1
± 10.18 inches Hg 0.01
± 34.47kPa 0.01
± 11.53feet H2O 0.01
± 138.3inches H2O 0.1
± 351.5cm H2O 0.1
± 80.00oz in20.01
Warning: Pressure inputs of 10 psi or higher will damage the instrument. Do not
apply pressure higher than the maximum pressure listed in the specification table

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Support line [phone]
Technical Support: Extension 200; E-mail: [e-mail]
Repair & Returns: Extension 210; E-mail: [e-mail]
Product specifications subject to change without notice
For the latest version of this User Guide, Software updates, and other
up-to-the-minute product information, visit our website: www.extech.com
Extech Instruments Corporation, 285 Bear Hill Road, Waltham, MA 02451
Battery Replacement
When the low battery indicator BAT appears on the display or if the meter does not switch
on when the POWER button is pressed, it is necessary to replace the battery.
To replace the battery:
1. Open the battery compartment by sliding the meter’s rear panel in the direction of the
embossed arrow.
2. Replace the 9V alkaline battery
3. Replace the battery compartment cover.
Conversions
Useful conversion Factors
From To Multiplier
in of H2O in of Hg 0.07355
in of H2O cm of Hg 2.54
mm of Hg in of H2O 0.03937
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Care Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.
Copyright ©2008 Extech Instruments Corporation (a FLIR company)
All rights reserved including the right of reproduction in whole or in part in any form.