General DCFM8906 User Manual
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General DCFM8906 User Manual

Digital one piece airflow meter with cfm display
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DIGITAL ONE PIECE
AIRFLOW METER WITH
CFM DISPLAY
USER'S MANUAL
DCFM89 6
Please read this manual carefully and thoroughly before using this product.

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  • Page 1 DIGITAL ONE PIECE AIRFLOW METER WITH CFM DISPLAY USER’S MANUAL DCFM89 6 Please read this manual carefully and thoroughly before using this product.

  • Page 2: Table Of Contents

    TABLE OF CONTENTS Introduction ........3 Key Features ....... . . 4 What’s in the Case .

  • Page 3: Introduction

    LCD. The DCFM8906 can display its air speed and airflow volume measurements in Imperial or metric units and its temperature measurements in degrees Fahrenheit or Celsius. A 20-minute auto power off function (which can be disabled to enable long- term recordings of air speed) helps extend battery life.

  • Page 4: Key Features

    PRODUCT OVERVIEW Figure 1 shows the labels and positions of the six control buttons on the front of the DCFM8906. The figure also shows all possible indications on the LCD below the control panel. Familiarize yourself with the buttons’ functions and the meanings of the display indications before moving on to the Setup Instructions.

  • Page 5: Control Buttons

    Fig. 1. The DCFM8906’s controls and indicators CONTROL BUTTONS ON-OFF RESET Turns meter on and off When pressed with AVERAGE button, resets default air speed and temperature units When pressed with HOLD button, disables auto power off function...
  • Page 6 MODE VELOCITY FREE AREA FLOW When pressed, places meter in airflow volume measurement mode Used with HOLD and AVERAGE buttons to enter free area dimensions AVERAGE MULTI-POINT When pressed, calculates and displays average of stored air speed measurements for up to eight points Used with HOLD and MODE buttons to enter free area dimensions in airflow volume measurement mode When pressed with ON-OFF RESET button, resets default...
  • Page 7 MIN/MAX REC SINGLE-POINT When pressed once, meter begins recording air speed at a single point. Default display is average air speed since recording began Next press changes display to real-time air speed Next two presses change display to minimum and maximum air speeds since recording began Next press returns display to average air speed All possible display indications and their meanings...
  • Page 8 Square feet. Lit during entry of free area dimensions in Imperial mode Square meters. Lit during entry of free area dimensions in metric mode Cubic feet per minute. Unit of airflow volume readings in Imperial mode Cubic meters per second. Unit of airflow volume readings in metric mode °C Degrees Celsius.

  • Page 9: Setup Instructions

    SETUP INSTRUCTIONS INSTALL BATTERY The meter’s battery compartment is accessible from the back of the unit. Use a Philips-head screwdriver to remove the one screw holding the battery compartment cover in place. Remove the cover and set it aside. Then plug the included 9V battery into the wired socket inside the compartment.
  • Page 10 Fig. 2. The meter’s default initial display after being powered on To make an air speed measurement, place the meter in the airstream leaving the HVAC system duct or register. Be sure to orient the meter so its vanes are centered in the stream and its axes are as perpendicular to the stream as possible (Fig.3).

  • Page 11: Recording Air Speeds At A Single Point

    Note: Held readings are deleted when the meter is powered off. RECORDING AIR SPEEDS AT A SINGLE POINT The DCFM8906 can record (store) air speeds at a single point during recording sessions lasting up to two hours. Based on these stored measurements, it can calculate and display: •...
  • Page 12 • The minimum air speed recorded since the session began • The maximum air speed recorded since the session began These three air speed readings can be very helpful for comparing the effects of different equipment settings during an HVAC/R system installation or repair. To initiate recording, place or secure the meter in the airstream and press the MIN/MAX REC SINGLE-POINT button.

  • Page 13: Displaying The Average Air Speed At Multiple Points

    DISPLAYING THE AVERAGE AIR SPEED AT MULTIPLE POINTS The DCFM8906 can calculate and display the average of air speed measurements made at up to different points. This feature makes it unnecessary to determine the “best” place to...
  • Page 14 make a performance measurement inside an HVAC/R duct. A multi-point average air speed reading is inherently more representative of a system’s output than any single-point reading, whether in the center of a duct or near one of its sides. To make and store the multiple measurements, use the HOLD and MIN/MAX REC SINGLE-POINT buttons.
  • Page 15 Once the lower display resumes showing temperature and the Hold indication disappears, make and store another air speed measurement at a second point by pressing the HOLD and MIN/MAX buttons in order again. This will sound the beeper and briefly replace the temperature reading in the lower display by the number 2.

  • Page 16: Converting To Airflow Volume Measurements

    POINT button until the beeper sounds twice. CONVERTING TO AIRFLOW VOLUME MEASUREMENTS The DCFM8906 can make and display real-time, maximum, minimum and average airflow volume measurements at a single point or multiple points. To enable the meter to make these measurements, you must enter the free area dimensions of the grille or register through which the air source flows.
  • Page 17 Fig. 7. The initial display produced by pressing the MODE button The value you need to enter is the area of the grille or register. Inspect the grille or register to determine whether the manufacturer stamped its area somewhere on it. If you do not see a number followed by the unit ft , measure the area yourself.
  • Page 18 To display the real-time airflow volume measurement associated with a real-time air speed measurement at a single point, press the MODE button. Note that doing so 1) causes the word FLOW to appear on the top line of the upper readout and 2) changes the unit at the right of the displayed value from fpm to cfm (an abbreviation of cubic feet per minute, or ft /min).

  • Page 19: Displaying The Average Air Speed At

    SINGLE-POINT button advances the display to the next step in a four-step cycle comprising average, real-time, minimum and maximum measurements. To exit recording mode or clear the stored measurements, press and hold the MIN/MAX REC SINGLE-POINT button until the beeper sounds twice. The meter will then resume displaying real-time airflow volume measurements without recording them.

  • Page 20: Switching Between Imperial And Metric Units

    SWITCHING BETWEEN IMPERIAL AND METRIC UNITS If you prefer to display the meter’s air speed and airflow volume measurements in metric units and its temperature readings in Celsius units, you can change the default settings for those values. To change the default settings from Imperial and Fahrenheit (the factory defaults) to metric and Celsius, start by powering the meter off.
  • Page 21 To finish changing the default settings to metric and Celsius units: • Press the HOLD button to make the ft/m and °F indications disappear, leaving only m/s and °C on-screen. • Press the MIN/MAX button to make the letter S appear on-screen.

  • Page 22: Disabling Auto Power Off

    °C indications with the factory-default values ft/m and °F. DISABLING AUTO POWER OFF To avoid wasting battery charge, the DCFM8906 is programmed to power off automatically after 20 minutes of inactivity. Just before this function takes effect, the beeper will sound three times.
  • Page 23 To disable the auto power off function, you must power the meter off and then power it on in the following special way. Press and hold the HOLD button while pressing the ON-OFF RESET button once. Continue pressing and holding the HOLD button until the beeper sounds and the meter powers on with the display shown in Fig.

  • Page 24: Specifications

    SPECIFICATIONS Air Speed Measurement Range 80 to 5900 ft/m (0.4 to 30 m/sec) Air Speed Measurement Accuracy ±3% of full-scale reading Sampling Period in Recording Mode 1 second Airflow Volume Measurement Range 0 to 9,999 cfm (m /min) or cmm /min) Temperature Measurement Range 14°...

  • Page 25: Maintenance Tips

    Subject to certain restrictions, General will repair or replace this instrument if, after examination, the company determines it to be defective in material or workmanship.

  • Page 26: Return For Repair Policy

    Acceptance of the exclusive repair and replacement remedies described herein is a condition of the contract for purchase of this product. In no event shall General be liable for any incidental, special, consequential or punitive damages, or for any cost, attorneys’ fees, expenses, or losses alleged to be a...
  • Page 27 NOTES ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________ ____________________________________________...
  • Page 28 New York, NY 10013-3567 PHONE (212) 431-6100 FAX (212) 431-6499 TOLL FREE (800) 697-8665 e-mail: sales@generaltools.com www.generaltools.com DCFM8906 User’s Manual Specifications subject to change without notice ©2011 GENERAL TOOLS & INSTRUMENTS NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS. MAN#DCFM8906 7/13/11...

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