DIGITAL ONE PIECE AIRFLOW METER WITH CFM DISPLAY USER’S MANUAL DCFM8906 Please read this manual carefully and thoroughly before using this product.
TABLE OF CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 What’s in the Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 8 Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INTRODUCTION Thank you for purchasing General Tools & Instruments’ DCFM8906 Digital One Piece Airflow Meter with CFM Display. Please read this user’s manual carefully and thoroughly before using the instrument. The DCFM8906 is a professional-grade vane anemometer that can not only measure air speeds exiting an HVAC/R system’s or blower’s grille or register, but also convert those readings to airflow volume measurements.
KEY FEATURES • Measures and displays air speed and airflow volume in Imperial or metric units • Simultaneously displays temperature in °F or °C • One-handed operation • Records average, minimum and maximum air speed at a single point or multiple points • Data hold • Auto power off • CE and RoHS approved WHAT’S IN THE CASE The DCFM8906 comes fully assembled in a custom molded plastic case along with a “9V” battery and this user’s manual.
Fig. 1.
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 air speed and temperature units HOLD When pressed, holds (freezes) upper display re
MIN/MAX REC SINGLE-POINT When pressed once, meter begins recording air speed at a single point.
ft2 m2 cfm cms °C °F REC AVG MIN MAX – 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 Degrees Celsius. Temperature unit in metric mode Degrees Fahrenheit.
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. The terminals of the battery and the socket mate in only one way, with the smaller male terminal plugging into the larger female terminal.
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). DIRECTION OF AIRFLOW Fig. 3. How to orient the meter The upper display will read out the real-time air speed in units of ft/m.
To change the Imperial air speed measurement unit from ft/m to miles per hour (mph) or knots, use the SEL: MPH KNOTS button. Press the button once and the on-screen display unit will change to mil/h. Press the button again and the on-screen text will change to knots. Press the SEL: MPH KNOTS button again to return to ft/m units. Note: These display unit changes only remain in effect until the meter is powered off.
• 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.
MIN/MAX REC SINGLE-POINT button will delete that indication, but not REC. This signifies that the meter is still recording, but now displaying real-time air speed measurements. Pressing the MIN/MAX REC SINGLE-POINT button again will cause the indication MIN to appear. Now the upper display will show the minimum (slowest) air speed recorded since the recording session began. Pressing the MIN/MAX REC SINGLE-POINT button yet again will cause MAX to replace MIN.
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. Start by positioning the meter’s vanes at the first point to be measured. When the reading is stable, press the HOLD button.
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. Repeat the above two-step sequence up to six more times to make and store up to eight measurements at eight different points.
readings on the upper readout—without clearing the meter’s multi-point memory, press the HOLD button. To clear the multi-point memory, press and hold the AVERAGE MULTIPOINT 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.
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 ft2, measure the area yourself. Enter the free area one digit at a time. The largest value you can enter is 9.999 ft2, and the smallest is 0.001 ft2.
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 ft3/min). To return to displaying the air speed at the single point, press the MODE button again.
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.
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. Then power it on in a special way by pressing and holding the AVERAGE MULTI-POINT button while pressing the ON-OFF RESET button once.
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. • Press the HOLD button to make the number 1200 appear on-screen. • Press the MIN/MAX button again to make the letter S appear again. • Press the HOLD button again to generate the display shown in Fig. 9. vel m/s Fig. 9.
In metric mode, the only airflow volume unit available is cms (an abbreviation of cubic meters per second, or m3/sec). Pressing the SEL: MPH KNOTS button repeatedly cycles the air speed units through three available settings: m/s (the default), km/h and knots. To change the default metric air speed measurement unit from m/s to km/h (kilometers per hour or kmph), press the SEL: MPH KNOTS button once. Press it again to change the default air speed unit to knots.
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. 10. Fig. 10. The display indicating that the auto power off function has been disabled. This display will last for only a few seconds.
SPECIFICATIONS Air Speed Measurement Range Air Speed Measurement Accuracy Sampling Period in Recording Mode Airflow Volume Measurement Range Temperature Measurement Range Temperature Measurement Accuracy/Resolution Auto Power Off Display Size Vane Diameter Dimensions Weight (with battery) Power Source 24 80 to 5900 ft/m (0.4 to 30 m/sec) ±3% of full-scale reading 1 second 0 to 9,999 cfm (m3/min) or cmm (m3/min) 14° to 122°F (-10° to 50°C) ±2°F (±1°C)/0.1° After 20 minutes of inactivity 1.3 x 1.5 in.
MAINTENANCE TIPS If the display begins to flash or is blank in response to pressing the ON-OFF RESET button, replace the battery by following the Setup Instructions on p. 9. Remove the battery before storing the meter for an extended period of time. Do not drop or disassemble the meter or immerse it in water.
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 consequence of damage due to failure of, or defect in any product including, but not limited to, any claims for loss of profits.
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GENERAL TOOLS & INSTRUMENTS 80 White Street 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.
