TSI Instruments ACCUBALANCE 8371 Operation And Service Manual

ACCUBALANCE®

AIR CAPTURE HOOD

MODEL 8371

OPERATION AND SERVICE MANUAL

1980335, REVISION E

FEBRUARY 2013

Copyright©

TSI Incorporated / 2002-2013 / All rights reserved.

Address

TSI Incorporated / 500 Cardigan Road / Shoreview, MN 55126 / USA

Fax No.

[phone]
LIMITATION OF WARRANTY AND LIABILITY (effective June 2011)

(For country-specific terms and conditions outside of the USA, please visit www.tsi.com.)
Seller warrants the goods sold hereunder, under normal use and service as described in the operator's
manual, shall be free from defects in workmanship and material for 24 months, or if less, the length of time

specified in the operator's manual, from the date of shipment to the customer. This warranty period is
inclusive of any statutory warranty. This limited warranty is subject to the following exclusions and
exceptions:

a. Hot-wire or hot-film sensors used with research anemometers, and certain other components when

indicated in specifications, are warranted for 90 days from the date of shipment;
b. Pumps are warranted for hours of operation as set forth in product or operator’s manuals;
c. Parts repaired or replaced as a result of repair services are warranted to be free from defects in

workmanship and material, under normal use, for 90 days from the date of shipment;
d. Seller does not provide any warranty on finished goods manufactured by others or on any fuses,

batteries or other consumable materials. Only the original manufacturer's warranty applies;
e. Unless specifically authorized in a separate writing by Seller, Seller makes no warranty with respect to,

and shall have no liability in connection with, goods which are incorporated into other products or

equipment, or which are modified by any person other than Seller.
The foregoing is IN LIEU OF all other warranties and is subject to the LIMITATIONS stated herein. NO

OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR PARTICULAR PURPOSE OR
MERCHANTABILITY IS MADE. WITH RESPECT TO SELLER’S BREACH OF THE IMPLIED WARRANTY
AGAINST INFRINGEMENT, SAID WARRANTY IS LIMITED TO CLAIMS OF DIRECT INFRINGEMENT

AND EXCLUDES CLAIMS OF CONTRIBUTORY OR INDUCED INFRINGEMENTS. BUYER’S

EXCLUSIVE REMEDY SHALL BE THE RETURN OF THE PURCHASE PRICE DISCOUNTED FOR
REASONABLE WEAR AND TEAR OR AT SELLER’S OPTION REPLACEMENT OF THE GOODS WITH
NON-INFRINGING GOODS.

TO THE EXTENT PERMITTED BY LAW, THE EXCLUSIVE REMEDY OF THE USER OR BUYER, AND
THE LIMIT OF SELLER'S LIABILITY FOR ANY AND ALL LOSSES, INJURIES, OR DAMAGES
CONCERNING THE GOODS (INCLUDING CLAIMS BASED ON CONTRACT, NEGLIGENCE, TORT,
STRICT LIABILITY OR OTHERWISE) SHALL BE THE RETURN OF GOODS TO SELLER AND THE
REFUND OF THE PURCHASE PRICE, OR, AT THE OPTION OF SELLER, THE REPAIR OR
REPLACEMENT OF THE GOODS. IN THE CASE OF SOFTWARE, SELLER WILL REPAIR OR REPLACE
DEFECTIVE SOFTWARE OR IF UNABLE TO DO SO, WILL REFUND THE PURCHASE PRICE OF THE
SOFTWARE. IN NO EVENT SHALL SELLER BE LIABLE FOR LOST PROFITS OR ANY SPECIAL,
CONSEQUENTIAL OR INCIDENTAL DAMAGES. SELLER SHALL NOT BE RESPONSIBLE FOR
INSTALLATION, DISMANTLING OR REINSTALLATION COSTS OR CHARGES. No Action, regardless of
form, may be brought against Seller more than 12 months after a cause of action has accrued. The goods
returned under warranty to Seller's factory shall be at Buyer's risk of loss, and will be returned, if at all, at
Seller's risk of loss.

Buyer and all users are deemed to have accepted this LIMITATION OF WARRANTY AND LIABILITY,
which contains the complete and exclusive limited warranty of Seller. This LIMITATION OF WARRANTY
AND LIABILITY may not be amended, modified or its terms waived, except by writing signed by an Officer of
Seller.

Service Policy

Knowing that inoperative or defective instruments are as detrimental to TSI as they are to our
customers, our service policy is designed to give prompt attention to any problems. If any malfunction is
discovered, please contact your nearest sales office or representative, or call TSI's Customer Service
department at [phone] (USA) or (001 651) 490-2811 (International) or visit www.tsi.com.

Trademarks

TSI®, TSI logo, and AccuBalance® are trademarks of TSI Incorporated.

iii

CONTENTS

ABOUT THIS MANUAL............................................................................ V

Formatting and Typography ............................................................... v

INTRODUCTION ...................................................................................... VI

SET UP ..................................................................................................... 1

Unpacking ........................................................................................... 1

Item ..................................................................................................... 2

Parts Identification .............................................................................. 3

Display.......................................................................................... 3

Display Units ................................................................................ 5

Keypad ......................................................................................... 5

Preparing the Instrument for Use ....................................................... 6

Installing the Batteries .................................................................. 6

Hood Assembly ............................................................................ 6

Basic Operation .................................................................................. 8

Start-Up ........................................................................................ 8

Selecting Flow Direction .............................................................. 8

Taking a Flow Measurement ........................................................ 8

Turning the AccuBalance® Air Capture Hood Off ......................... 9

Automatic Shut-off ........................................................................ 9

OPERATIONS IN MORE DETAIL .......................................................... 11

Keypad Functions ............................................................................. 11

Field Calibration ................................................................................ 12

Changing Hoods ............................................................................... 13

Changing DIP Switch Settings .......................................................... 17

Setting: Function .............................................................................. 18

Connecting the Optional Printer ....................................................... 19

MAINTENANCE ...................................................................................... 21

Fabric Hood ...................................................................................... 21

Part Number ..................................................................................... 21

Meter ................................................................................................. 22

Manifold ............................................................................................ 22

Cases ................................................................................................ 22

Calibration ......................................................................................... 22

TROUBLESHOOTING ............................................................................ 23

BACK PRESSURE ................................................................................. 25

SPECIFICATIONS .................................................................................. 27

iv

About this Manual

This manual explains how to set up, operate and maintain the
AccuBalance® Air Capture Hood Model 8371. Read it thoroughly before
using the instrument.

Formatting and Typography

Note that step-by-step instructions are numbered in boldface type: 1, 2,
3, etc., set flush-left against the margin.

References to the front panel keys on the AccuBalance
along with the instrument's displayed readout, are represented in this
manual by the typeface called Helvetica Narrow. In addition to the different
typeface, displayed messages appear in quotes.

When reference is made to other sections of the manual, the section title
is italicized.

Example: The "SAMPLE" message appears along with a flow value after
the SAMPLE button has been activated (from Display in Chapter 1).

HELP!

For technical assistance with this instrument, questions about the
manual, or if your air capture hood needs repair or recalibration, please
call TSI Customer Service at [phone] or [phone]. Product
application notes are designed to provide more information on the
product to the user. Application notes, as well as other related material,
can be obtained by calling TSI or by visiting the TSI web site at

http://www.tsi.com.

®

capture hood,

v

Introduction

C A U T I O N

WHILE USING THE ACCUBALANCE

®

AIR BALANCING

INSTRUMENT TO TEST AIR FLOW IN DUCTS, YOU MAY
COME INTO CONTACT WITH OR BE EXPOSED TO DUST,
POLLEN, MOLD, FUNGUS, OR OTHER AIRBORNE
CONTAMINANTS. IF YOU ARE OR MAY BE SENSITIVE TO
DUST, POLLEN, MOLD, FUNGUS, OR OTHER AIRBORNE
CONTAMINANTS, ALWAYS USE AN APPROPRIATE MASK
OR RESPIRATOR WHILE EMPLOYING THE ACCUBALANCE®
AIR BALANCING INSTRUMENT.

The TSI Model 8371 AccuBalance® capture hood is an instrument
designed to measure the air flow from diffusers and grilles or the air flow
entering exhaust outlets. The AccuBalance® capture hood is lightweight
and easy to use. The instrument can display the measured air flow in
four different units: standard cubic feet per minute (SCFM), standard
liters per second (Std l/s), standard cubic meters per hour (Std m3/hr),
and standard cubic meters per minute (Std m3/min). All readings may
also be displayed in actual flow conditions.

The AccuBalance® capture hood consists of a fabric hood, a molded
plastic base which contains an electronic meter, and a flow sensing
manifold located within the base. Air flowing through the hood is
measured by a hot-film sensor located in the central hub of the flow
sensing manifold. The twenty-four pairs of flow sensing ports in the
manifold are strategically located so that the AccuBalance® capture hood
provides the highest degree of measurement accuracy, even in non­uniform flow conditions.

The AccuBalance® capture hood is temperature-compensated to display
a standard flow rate: SCFM, Std l/s, Std m3/hr, and Std m3/min.
Standard flow rate is defined as the volumetric flow rate at standard
conditions of 70°F (21.1°C) and 14.7 pounds per square inch (760
mmHg) barometric pressure. Standard flow rate is the measurement
used most often in ventilation applications.

vi

1

Chapter 1

Set Up

This chapter guides you through unpacking, setting up, and getting
started using your AccuBalance® Air Capture Hood. See Chapter 2 for a
detailed description of all operating features.

Figure 1: The AccuBalance

®

Air Capture Hood

Unpacking

Carefully unpack the instrument and accessories from the carrying case.
Check the individual parts against the list of components in Tables 1
through 3. If any are missing or damaged, notify TSI immediately.

2

Table 1 List of components

Qty

Item

Part No.

1

Model 8371 base

N/A

1

2 ft x 2 ft (610 mm x 610 mm) hood fabric

1307060

6

Frame support poles

1081390

4

2 ft (610 mm) frame tubing*

1081262

6

Right angle tubing connectors*

1081584

1

Battery holder

1081279

4

C-size batteries

1208018

1

Battery compartment cover

1081458

1

Carrying case

1319067

1

Operation and Service Manual

1980335

Qty

Item

Part No.

1

2 ft x 4 ft (610 mm x 1220 mm) hood fabric

1801065

1

1 ft x 4 ft (305 mm x 1220 mm) hood fabric

1801066

6

2 ft (610 mm) frame tubing

1081262

4

1 ft (305 mm) frame tubing

1081260

6

Right angle tubing connectors

1081584

6

Straight tubing connectors

1302833

Qty

Item

Part No.

1

2 ft x 4 ft (610 mm x 1220 mm) hood fabric

1801065

1

1 ft x 4 ft (305 mm x 1220 mm) hood fabric

1801066

1

1 ft x 5 ft (305 mm x 1525 mm) hood fabric

1801067

1

3 ft x 3 ft (915 mm x 915 mm) hood fabric

1801068

6

2 ft (610 mm) frame tubing

1081262

4

1 ft (305 mm) frame tubing

1081260

6

Right angle tubing connectors

1081584

6

Straight tubing connectors

1302833

2

1x tube connectors

1081580

*Four 2 ft frame tubings and four of the right angle connectors are shipped
assembled inside the top of the hood fabric.

Table 2 List of components: -3 Hood Kit (adds 2 hoods to the base kit)

Table 3 List of components: -5 Hood Kit (adds 4 hoods to the base kit)

Be sure to register your instrument, it allows TSI to inform you of product
updates. To register, visit the TSI web site (http://register.tsi.com/).

Chapter 1

3

Parts Identification

1 6 5 2 3

4

Before proceeding with assembly and use of the AccuBalance® capture
hood, please become familiar with the various parts of the instrument.
Refer to tables 1 through 3 for part descriptions and Figure 2 for general
location of major items.

Figure 2: AccuBalance® Components

1 Fabric hood - Basic hood assembly is covered later in this chapter,

other hoods are discussed in Chapter 2.

2 Right handle with SAMPLE button - used for capturing information on

the display.

3 Meter base.
4 Electronic meter and display - Detailed keypad functions are

covered in Chapter 2.

5 Printer bracket - Allows the portable printer to be attached to the

AccuBalance® base for ease of use and printing of data.

6 Left handle with PRINT button - Used to print that which is on the

display value to the portable printer.

Display

Each time the AccuBalance® capture hood is turned on, all
segments of the display will be shown momentarily. Below is a list
of items that will appear on the display and their use.

Set-Up

4

3 2 5 9 8 4 1

6, 7

Figure 3: Display of the Model 8371

1 Flow units: CFM (cubic feet per minute), l/s (liters per

second), m3/hr (cubic meters per hour), and m3/min (cubic
meters per minute). The AccuBalance® capture hood
indicates flow already corrected to "standard" conditions.
Actual flow conditions can be shown by pressing the
ACTUAL/STANDARD key (See Chapter 2 for more detail
operation)

2 Flow value: Large digits. See specifications for range and

resolution.

3 Message area: Small digits.
4 Flow direction arrows: Indicates if supply or return air flow

calibration is being utilized by the AccuBalance® capture
hood.

Notice: Be sure this arrow points in the direction of flow through the

AccuBalance® capture hood, otherwise the measurements made
will be inaccurate. To change the direction of the arrow, press
the RETURN/SUPPLY key.

5 “SAMPLE” will appear every time the SAMPLE button or the

button on the top of the right handle is pressed.

6 “% ” will appear along with a value on the display during

power-up to indicate the percent of battery life remaining.

7 The symbol will flash when the batteries have only

about 10% life remaining. When the battery is too low to
power the instrument, “LO ” is displayed momentarily

before the instrument is automatically turned off.

Chapter 1

5

8 “STD” or “ACTUAL” will be displayed at all times. “STD” refers to

readings that are based on standard conditions of

29.92 in. Hg (760 mm Hg) and 70 F (21.1 C). “ACTUAL”
refers to readings that are converted to local conditions
based on temperature and barometric pressure. (See

Chapter 2 for more details.)

9 “K

”: K factor symbol to indicate that the readings have an

f

adjustment factored in.

Display Units

The AccuBalance® capture hood is shipped with cubic feet per
minute (CFM) as the default flow unit (unless the metric version was
ordered). To change the units to l/s (liters per second), m3/hr (cubic
meters per hour), or m3/min (cubic meters per minute), see

Changing DIP Switch Settings in Chapter 2.

Keypad

Below is a drawing of the keypad, Figure 4, for the Model 8371. The
keys are referenced in the Basic Operation section of this chapter
and in Chapter 2 - Operations in More Detail.

Figure 4: Keypad for the Model 8371

Set-Up

6

Preparing the Instrument for Use

Installing the Batteries

The AccuBalance® capture hood requires four C-size batteries to
operate. For convenience, four alkaline batteries are included with
the AccuBalance® capture hood.

To install the batteries, follow these three steps:
1 Remove the battery cover located behind the electronic meter on

the inner side of the AccuBalance® capture hood base. To
remove the battery cover, pull up on the latches located on the
top and bottom of the cover.

2 Place batteries in the battery holder located inside the battery

compartment. Follow the illustration on the battery holder for
correct battery orientation.

3 Replace the battery cover. Notice that the battery cover is

designed to fit only one way, with the tab pointing toward the
fabric. Engage the latches by pressing down on them.

Notice: Remove batteries from the battery compartment during shipping,

travel and transport. Jostling may jar the batteries loose and
cause damage to the AccuBalance® capture hood.

If fresh, new alkaline batteries are used, the value will be near 100­percent when first turned on. Other batteries, such as NiCd
batteries, may show a lower value even when they are fully
charged.

Notice: The percent power remaining will not be accurate for NiCd

batteries because they do not discharge linearly with power use.

Hood Assembly

The AccuBalance
partially assembled with the 2 ft x 2 ft nylon hood attached to the
base. To use another hood size, see Changing Hoods in Chapter 2.

To complete the assembly of the 2 ft x 2 ft hood, follow these six
steps:

1 Place the base of the AccuBalance

®

capture hood is shipped from the factory

®

capture hood on the floor.

Chapter 1

7

2 Lift the top of the fabric. Insert one end of a support pole into its

Rod to pole
cup

pole mount in the base of the AccuBalance® capture hood.
There is a cup in each corner of the frame to accept the other
end of each support pole. Helpful Hint: This step is made simpler
by temporarily resting the opposite corner of the fabric top on a
table edge.

3 Grasp the support pole. Bend the pole slightly to insert the top

end of the pole into the support pole cup located in the corner of
the fabric frame as shown in Figure 5.

Figure 5: Installing a Support Pole

4 Insert the second support pole into the pole mount on the

opposite side of the AccuBalance® capture hood base.

5 Repeat step 3 for the second support pole.
6 Repeat steps 4 and 5 for the remaining two support poles.

Set-Up

8

Basic Operation

C A U T I O N

WHILE USING THE ACCUBALANCE

®

AIR BALANCING

INSTRUMENT TO TEST AIR FLOW IN DUCTS, YOU MAY
COME INTO CONTACT WITH OR BE EXPOSED TO DUST,
POLLEN, MOLD, FUNGUS, OR OTHER AIRBORNE
CONTAMINANTS. IF YOU ARE OR MAY BE SENSITIVE TO
DUST, POLLEN, MOLD, FUNGUS, OR OTHER AIRBORNE
CONTAMINANTS, ALWAYS USE AN APPROPRIATE MASK
OR RESPIRATOR WHILE EMPLOYING THE ACCUBALANCE®
AIR BALANCING INSTRUMENT.

Start-Up

Press the ON/OFF button on the meter to turn on the power. The
display will initially indicate the percent of battery power remaining.

During start-up the AccuBalance® capture hood performs a self test
of its electronic functions. If an error is found, an error message will
appear on the display. Refer to Chapter 4, Troubleshooting, if an
error message appears. If no errors are found, the AccuBalance®
capture hood will proceed to the continuous measurement mode.

Selecting Flow Direction

Each AccuBalance® capture hood is calibrated for supply and return
air separately for increased accuracy. The AccuBalance® capture
hood will assume that air is flowing in the same direction as the
arrow on the right-hand side of the display. Be sure this arrow
points in the direction of flow through the AccuBalance® capture
hood, otherwise measurements will be inaccurate. To change the
direction of the arrow press the RETURN/SUPPLY button.

Taking a Flow Measurement

You are now ready to start measuring flow rates. First, turn on the
AccuBalance® capture hood and select the appropriate flow
direction. For measuring supply air flow, the arrow must point down
away from the hood fabric; for return air flow measurements, the
arrow must point up toward the hood fabric.

Press the top of the AccuBalance® capture hood against the
perimeter edge of the diffuser or grille so as to form a seal.

Chapter 1

9

The AccuBalance

®

capture hood will begin to display values on a

continuous basis. When you are ready to read a value, press the
SAMPLE button or the button on the top of the right handle. The

display will show the word “SAMPLE” for the length of time as

determined by the TIME CONSTANT. When the sample is complete,
the unit will beep and the value will remain on the display until
SAMPLE is pressed again and the meter will return to continuous
measuring mode.

If the readings are fluctuating, adjust the TIME CONSTANT to a slower
value. Changing the TIME CONSTANT is detailed in the Keypad

Function section of Chapter 2

When making a flow measurement, keep objects out of the flow
path at the base of the AccuBalance

®

capture hood (one foot

clearance minimum). However, it is acceptable to have a hand
supporting the air capture hood at the bottom of the base.

Notice: The AccuBalance® capture hood must be kept in place

during the entire sample interval and until the time-averaged
measurement appears on the display.

Turning the AccuBalance® Air Capture Hood Off

To turn off the AccuBalance® capture hood, simply press the
ON/OFF button.

Automatic Shut-off

The AccuBalance® capture hood will automatically shut itself off if
no switches or buttons have been pressed for 10 minutes. This
feature minimizes accidental loss of battery power. This feature
may be disabled by changing the factory settings. This is discussed
in the DIP Switch Setting section of the next chapter.

Set-Up

10

(This page intentionally left blank)

Chapter 1

11

Chapter 2

Operations in More Detail

This chapter presents more detail on the various features of the
AccuBalance® capture hood and explains how to change fabrics and
assemble different hood sizes. The AccuBalance® capture hood will
acknowledge that a key has been pushed by producing a beep. This
beep can be disabled as explained in the DIP Switch Settings section of
this chapter.

Keypad Functions

ON/OFF

Press to toggle between having the instrument on and off.

SUPPLY/RETURN

Press to toggle between measuring supply flow and return flow. The
arrows on the display will indicate the direction of the flow ( for return,
 for supply).

K FACTOR

Volume measurements with the AccuBalance® capture hood is a means
to take readings more quickly than methods used in the past. However,
all capture hood devices are affected by various types of diffusers,
means of connecting the diffuser to the duct work, and the type of duct
work. The AccuBalance® capture hood is calibrated by attaching it to a
2 foot x 2 foot, 4 way throw diffuser. In some circumstances it is

necessary to traverse the ductwork to determine the “true” flow value.

This true value is then compared to the AccuBalance® capture hood.
This comparison is a K Factor or correction factor.

Press the K FACTOR button to toggle the K factor on or off. The “K
symbol is shown on the display when the K factor is being used in the
calculation. Press and hold the K FACTOR button until the current K factor
is displayed. Release the button and use the  or  button to change
the factor. Press ENTER to accept it and return to measuring mode. The
range of K factors allowed will be 0.1 to 2.00. The default value is 1.00.

ACTUAL/STANDARD

Press the ACTUAL/STANDARD button to toggle between displaying actual

and standard flow rate. “STD” or “ACTUAL” will light up on the display
(standard is the default). Press and hold this button to view, enter, or
change the barometric pressure and ambient temperature. When the
button is pressed and held, the barometric pressure entered will be

”

f

12

displayed. Release the button, use the  buttons to change the value
and ENTER to accept it. The ambient temperature will then be displayed.
Press the  or  button to change the value and ENTER to accept it and
return to measuring mode. Ambient temperature and barometric
pressure can also be set by pressing either  when the parameter is
displayed during power-up.

TIME CONSTANT

Press to display the current time constant. Press  to scroll through
the time constant choices, which are 1 s, 3 s, 5 s, 10 s, 15 s, 20 s. Press
ENTER to accept choice and return to measuring mode. The default value
is 1 s.

PRINT or LEFT HANDLE BUTTON
Press to print the reading on the display to the portable printer.


Press to scroll through choices. Press either  or  to set barometric
pressure and temperature when they are displayed during power-up.
Used in field calibration mode for flow.

SAMPLE or RIGHT HANDLE BUTTON
Press to take a sample averaged over the length of the time constant.

“SAMPLE” will flash on the display while the reading is being taken, and
then the value and “SAMPLE” will be held on the display until SAMPLE is

pressed again, at which time the instrument will return to measuring
mode. This also prints the result to the portable printer if connected.

LIGHT
Press to toggle between having the back-lit display turn on and off.
When the instrument is turned off, the backlight turns off and does not
automatically turn on the next time the instrument is turned on.

Field Calibration

Turn DIP switch 7 to the on position, see DIP Switch Settings section
later in the chapter. To adjust the flow value, press both the  and 

buttons simultaneously. When “CAL” is displayed, release the buttons.

Press either the  or  buttons to change to a desired percentage
adjustment and press ENTER to accept it. The percentage adjustment
ranges from 0% to plus or minus 12.5%. To use the instrument with the
adjusted values, DIP switch 7 must remain in the ON position. All
adjustment values and offsets are stored in the instrument and will
remain the same until changed again. To return to all factory settings,
turn DIP switch 7 off.

Chapter 2

13

Changing Hoods

The AccuBalance® capture hood is shipped with a 2 ft x 2 ft hood
attached to the base. Four other hood sizes are available from TSI and
can be purchased separately. Available hood sizes are identified by the
dimensions of the frame structure at the top of the hood and include
2 ft x 4 ft, 1 ft x 4 ft, 1 ft x 5 ft and 3 ft x 3 ft .

To change hood sizes, first remove the hood currently attached to the
base. To remove the attached hood, first unlatch the cinch belt where the
fabric is attached to the base. Then remove the fabric from its frame
structure by peeling back the Velcro from the aluminum frame tubing.
Notice that the fabric stretches around the outside, then up and over the
frame structure. The Velcro on the fabric reaches down to mate with the
Velcro on the frame structure. Notice also that all Velcro surfaces on the
frame tubing face inward. Finally, fold up the fabric just removed so that
it can fit into one of the accessory pockets inside the AccuBalance®
carrying case. It is a good idea to fold the fabric so that the tag identifying
its size remains visible for future reference.

2 ft x 4 ft Hood

To assemble and attach the 2 ft x 4 ft hood, carefully follow these
10 steps:

1 Build the 2 ft x 4 ft frame structure as shown in Figure 6 using six

2 ft aluminum frame tubing pieces, four right-angle tubing
connectors, and two straight tubing connectors. Remember to
construct the frame so that all Velcro surfaces face in (toward the
center of the structure).

Notice: Make sure that all support pole cups in the aluminum frame

tubing pieces are facing downward.

Operations in More Details

14

Figure 6: Diagram of 2 ft x 4 ft frame

2 Unfold the 2 ft x 4 ft hood fabric.
3 Insert the frame into the fabric and fasten the fabric to the frame

using the Velcro surfaces. The fabric stretches around the outside,
then up and over the frame structure. The Velcro® on the fabric
reaches down to mate with the Velcro® on the inner surface of the
frame structure. When completed, the soft rubber gasket material
should lie in a straight line along the top surface of all four sides of
the frame.

Notice: Be sure to press the Velcro surfaces firmly together. When

completed, the hood fabric will be stretched fairly taut and will
require good bonding of the fabric to the frame.

4 Stretch the cinch belt at the bottom of the fabric over the lip around

the top of the molded plastic base of the AccuBalance® capture
hood. Align the seams of the fabric panels with the pairs of screw
heads that hold the four pole mounts to the AccuBalance® base.
Align so that the cinch belt latch is on the side of the base opposite
the electronics meter.

5 Pull the strap at the latch very tight to attach the fabric to the base.

Make sure that the strap stays tucked under the protruding lip all
around the top of the base. Pay particular attention to where the
strap passes the handles.

Chapter 2

15

6 Now it is time to install the support poles. Four white marks are

located on the inside top edge of the fabric. These marks identify
the location of cups on the underside of the frame tubing that will
accept the ends of the support poles.

At this time it is helpful to be near a table or some other thigh-high

surface to help hold up the fabric while installing the first support
pole.

7 With the base of the AccuBalance® capture hood on the floor, lift the

fabric frame up so that a white mark is directly in front of you.
Support the opposite side of the frame structure on a nearby table
or other level surface.

Take one support pole and insert one end into its pole mount in the

AccuBalance® base.

Bend the pole slightly to guide the other end into the corresponding

support pole cup located on the underside of the frame near the
white mark on the fabric.

8 Repeat step 7 until all four support poles are installed.
9 Now that the hood is assembled and the fabric is stretched tight, it

is a good practice to check the rubber gasket around the top edge
of the AccuBalance® capture hood fabric. In order to achieve a good
straight alignment of the rubber gasket along the top of the frame
structure, you may need to peel back and re-attach small portions
of the Velcro surfaces.

10 Finally, at the corners, tuck the straight rubber gasket flaps under

the edges cut at an angle. This will create a virtually leak-free, soft,
pliant seal.

1 ft x 4 ft Hood

To assemble and attach the 1 ft x 4 ft hood, carefully follow these
10 steps:

1 Build the 1 ft x 4 ft frame structure as shown in Figure 7 using four

2 ft aluminum frame tubing pieces, two 1 ft aluminum frame tubing
pieces, four right-angle tubing connectors, and two straight tubing
connectors. Remember to construct the frame so that all Velcro
surfaces face in (toward the center of the structure).

Notice: Make sure that all support pole cups in the aluminum frame

tubing pieces are facing downward.

Operations in More Details

16

Figure 7: Diagram of 1 ft x 4 ft frame

2 Unfold the 1 ft x 4 ft fabric hood.

Continue with steps 3 through 10, beginning on page 14.
1 ft x 5 ft Hood

To assemble and attach the 1 ft x 5 ft hood, carefully follow these
10 steps:

1 Build the 1 ft x 5 ft frame structure as shown in Figure 8 using four

2 ft aluminum frame tubing pieces, two 1x tube connectors, two 1 ft
aluminum frame tubing pieces, and four right-angle tubing
connectors. Remember to construct the frame so that all Velcro
surfaces face in (toward the center of the structure).

Notice: Make sure that all support pole cups in the aluminum frame

tubing pieces are facing downward.

Figure 8: Diagram of 1 ft x 5 ft frame

Chapter 2

17

2 Unfold the 1 ft x 5 ft fabric hood.
Continue with steps 3 through 10, beginning on page 14.

3 ft x 3 ft Hood

To assemble and attach the 3 ft x 3 ft hood, carefully follow these 10
steps:

1 Build the 3 ft x 3 ft frame structure as shown in Figure 9 using four 2

ft aluminum frame tubing pieces, four 1 ft aluminum frame tubing
pieces, four right-angle tubing connectors, and four straight tubing
connectors. Remember to construct the frame so that all Velcro
surfaces face in (toward the center of the structure).

Notice: Make sure that all support pole cups in the aluminum frame

tubing pieces are facing downward.

Figure 9: Diagram of 3 ft x 3 ft frame

2 Unfold the 3 ft x 3 ft fabric hood.

Continue with steps 3 through 10, beginning on page 14.

Changing DIP Switch Settings

To change flow units and time constants, adjust the settings of the DIP
switches located inside the battery compartment. To gain access to the
DIP switches, first turn off the AccuBalance® capture hood and lay down
the instrument with the electronic meter facing down.

Remove the battery compartment cover by pulling up on the two latches.
Switches numbered 1 through 8 are located in the corner of the battery
compartment. To allow easier access to the switches, remove or tilt up
the battery pack. The DIP switches are shown in Figure 10.

Operations in More Details

18

Figure 10: Location of DIP Switches

Switch Number

Setting: Function

1,2

1 OFF, 2 OFF: Flow units = CFM
1 OFF, 2 ON: Flow units = m3/hr
1 ON, 2 OFF: Flow units = l/s
1 ON, 2 ON: Flow units = m3/min

3

OFF: Pressure units = in. Hg
ON: Pressure units = mm Hg

4

OFF: Temperature units = F
ON: Temperature units = C

5

OFF: Auto shut off = on
ON: Auto shut off = off

6

OFF: Decimal for fractions
ON: Comma for fractions

7

OFF: Field calibration disabled
ON: Field calibration enabled

8

OFF: Audible buzzer on
ON: Audible buzzer off

To change the switch settings, use the tip of a ball-point pen, pencil,
compass, small screwdriver, or other small, pointed object. Refer to
Table 4 for switch settings.

Table 4: DIP Switch Settings

Chapter 2

19

Connecting the Optional Printer

To connect the optional printer to the AccuBalance® capture hood, locate
the Printer Interface Cable (supplied with the optional printer) and
connect the 9-pin end labeled “PRINTER” to the printer and the other
end to the data port of the AccuBalance® capture hood. The printer can
be attached to the base of the AccuBalance® capture hood by clipping it
into the printer bracket located to the left of the display. The printer can
also be easily used by clipping it to the belt of the user. The printer must
be set to the same baud rate as the AccuBalance® capture hood. Always
turn the AccuBalance® capture hood on before the printer. If the printer
prints question marks (??????), asterisks (******), or random characters,
reset it by turning it off and then on again. If necessary, refer to the
Portable Printer Operation and Service Manual.

Caution: This symbol is used to indicate that the data
port of the AccuBalance® capture hood is not intended
for connection to a public telecommunications network.
Connect the data port only to another RS232 port.

Operations in More Details

20

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Chapter 2

21

Fabric Hood Size

Part Number

2 ft x 2 ft (610 mm x 610 mm)

800590

2 ft x 4 ft (610 mm x 1220 mm)

800591

1 ft x 4 ft (305 mm x 1220 mm)

800592

3 ft x 3 ft (915 mm x 915 mm)

800593

1 ft x 5 ft (305 mm x 1525 mm)

800594

Frame Kit

1081263

Chapter 3

Maintenance

The AccuBalance® capture hood is designed for long-term field use. If
the AccuBalance
be able to make precise measurements over a long time period. Some of
the components can be cleaned periodically. When cleaning the
components, please follow the instructions given below.

Fabric Hood

The hoods can be washed with mild detergent and cold water. When
washing the hood, keep the hood away from objects with sharp corners
or sharp edges. Careless cleaning may cause damage.

If the fabric gets ripped it should be replaced or repaired. Duct tape can
be placed over the rip on both sides of the fabric for temporary repair.

To replace a damaged fabric or to order a different fabric size, contact
TSI for replacement fabric information.

To order a new hood fabric, use the following part numbers shown in
Table 5.

Table 5: Hood Fabric Part Numbers

®

capture hood is used with reasonable care, it should

It is recommended that a frame kit be purchased whenever a hood other
than the 2 ft x 2 ft size is purchased. The frame kit contains all extra
frame tubing and connectors required to build frames for the various size
hoods. The frame kit consists of the following parts:

4 pieces 1-foot frame tubing
2 pieces 2-foot frame tubing
6 pieces straight tubing connectors

Meter

The AccuBalance® capture hood has a built-in electronic flow meter. Do
not try to detach the meter from the base. The AccuBalance® capture
hood should be used and stored within the specified temperature range,
32 to 140°F (0 to 60°C). The meter case, display screen and membrane
switch can be cleaned using a damp cloth with mild detergent solution.
Do not immerse the meter in water. Wipe the meter dry before use.

Manifold

If the flow sensing taps of the manifold become clogged with dust or
other material, clean them with a damp cloth. Keep the manifold in place
during cleaning. Do not apply excessive forces on the grid of the
manifold. If any part of the grid becomes damaged, please contact TSI
for repair information.

Cases

If the instrument case or storage case needs cleaning, wipe it off with a
soft cloth and isopropyl alcohol or a mild detergent. Never immerse the
AccuBalance® capture hood. If the meter face of the AccuBalance
capture hood becomes broken, it must be replaced immediately to
prevent access to hazardous voltage.

®

Calibration

TSI recommends an annual calibration for the AccuBalance® capture
hood. For a nominal fee, TSI will calibrate the unit and return it to you
with a certificate of calibration and NIST traceability. This “annual
checkup” assures you of consistently accurate readings. To calibrate the
AccuBalance® capture hood, please ship TSI the complete package that
includes the meter, the base, the manifold and any fabrics used.
Everything should be packed carefully within the AccuBalance® carrying
case and then inside a proper shipping box, such as the original shipping
box.

Ship directly to: TSI, Inc.

ATTN: Customer Service
500 Cardigan Road
Shoreview, MN 55126-3996

22 Chapter 3

23

Symptom

Possible Causes

Corrective Action

No display

Unit not switched on
Low or dead batteries
Dirty battery contacts

Battery holder not
connected

Press ON/OFF button
Replace the batteries
Clean the battery

contacts
Plug in battery holder

" "flashing on
the display

Low battery charge
Dirty battery contacts

Replace the batteries.
Clean the battery

contacts

"0" (Flow is under
range)

Trying to read too low a
flow

Object is blocking flow
through AccuBalance
capture hood

Sensor grid tubes are
plugged

AccuBalance capture
hood is not sealing
around diffuser

Flow may not be
measurable using the
AccuBalance capture
hood

Remove obstruction

Clean the tubes

Reposition the
AccuBalance capture
hood to form a seal

“OVER” (Flow is

over range)

Trying to read too high a
flow

Flow may not be
measurable using the
AccuBalance capture
hood

Chapter 4

Troubleshooting

Table 6 lists the symptoms, possible causes, and recommended
solutions for common problems encountered with the AccuBalance®
capture hood. If a symptom is not listed, or if none of the solutions solves
your problem, please contact TSI.

Table 6. Troubleshooting the AccuBalance

®

Air Capture Hood

Symptom

Possible Causes

Corrective Action

Flow reading
fluctuates badly

The flow is fluctuating

Use a longer time
constant

"ERR1" appears

Unit is or was recently in
ambient temperature
outside of operating
temperature

Temperature
compensation sensor is
damaged

Allow unit to stabilize in
the operating
temperature range of
32 to 140ºF (0 to 60ºC)

Return to the factory for
service

"ERR2" appears

The flow sensor is
giving an erroneous
reading

Return to the factory for
service

"ERR3" appears

The AccuBalance
capture hood has
detected a calibration
fault

Return to the factory for
service

24 Chapter 4

25

Appendix A

Back Pressure

It is commonly known that an air capture hood may induce a back
pressure. In general, back pressures are caused by restrictions in the
flow path as well as frictional pressure losses. In order to improve
accuracy and sensitivity, all air capture hoods incorporate a contracted
flow section. The contracted section restricts the flow through the hood
which induces a back pressure. A hood having a more abrupt contraction
than the AccuBalance® capture hood may induce greater back pressure
due to the turbulence caused by the abrupt contraction. In addition any
apparatus within the hood, such as supporting poles and the flow
manifold, also induces some frictional pressure drop.

Back pressure may cause slight errors in the flow measurements. Figure
11 shows the pressure drop through the AccuBalance® capture hood
over its entire flow range. As shown in the Figure, the back pressure is
only 0.05 in. H2O at a flow rate as high as 1000 CFM.

Figure 11: Pressure Drop through the

AccuBalance® Air Capture Hood

To make back pressure corrections, first determine the back pressure
correction factor, Cb. The back pressure correction factor, Cb, can be
determined as follows:
Vo
Cb = ---- (1)
V

where V and Vo are the average air velocities in the duct ahead of the
diffuser with and without the capture hood in place, respectively. With the
known correction factor, the back-pressure corrected flow can be
determined using Equation (2):

Back-pressure corrected flow = Displayed flow x Cb (2)

26 Appendix A

27

Appendix B

Specifications

Flow Range 30 to 2,000 CFM

(15.0 to 1,000 l/s,
50 to 3,500 m3/hr,

Accuracy 5% reading 5 CFM

Operating Temperature Range 32-140F (0-60C)
Instrument Operating Conditions Altitude up to 13,000 ft

Relative humidity up to 80% RH,
Pollution degree 1 in accordance

Weight (using 2 ft  2 ft in Hood) 7 lb 6 oz (3.4 kg)
Power 4 C-size batteries

Battery Life At least 40 hrs of continuous use
Carrying Case 26 in  26 in  7 in

Hood Sizes Available

Standard: 2 ft  2 ft; (610 mm  610 mm)
Optional: 2 ft  4 ft; (610 mm  1220 mm)

RS-232C Output ASCII Character codes
1200 Baud
No parity
8 data bits
1 stop bit
No handshaking

Specifications are subject to change without notice.

0.84 to 55.0 m3/min)

(5% reading 2.4 l/s,

5% reading 8.5 m3/hr,
5% reading 0.15 m3/min)

(4000 meters)
non-condensing
with IEC 664

(4 alkaline batteries provided)

(660 mm  660 mm  180 mm)

1 ft  4 ft; (305 mm  1220 mm)
1 ft  5 ft; (305 mm  1525 mm)
3 ft  3 ft; (915 mm  915 mm)

USA Tel: [phone]
UK Tel: [phone]
France Tel: [phone]
Germany Tel: [phone]

India Tel: [phone]
China Tel: [phone]
Singapore Tel: [phone]

TSI Incorporated – Visit our website www.tsi.com for more information.

P/N 1980335 Rev E ©2012 TSI Incorporated Printed in U.S.A.