Dwyer Instruments 477A Operating Manual

Bulletin D-26

Series 477A Handheld Digital Manometer

Specifications - Installation and Operation Instructions

SPECIFICATIONS

Service: Air and compatible gases.
Wetted Parts: Consult factory.
Accuracy: ±0.10% of full scale from 60 to 78°F

(15.6 to 25.6°C); ±1% of full scale from 32 to 60
and 78 to 104°F (0 to 15 .6 and 25.6 to 40°C).

Pressure Hysteresis: ±0.1% of full scale.
Pressure Limits: See chart.
Temperature Limits: 32 to 104°F (0 to 40°C).
Storage Temperature Limits: -4 to 176°F (-20

to 80°C).

Display: 4-digit LCD (.425˝ H x .234˝ W digits).
Resolution: See chart.
Power Requirements: 9 volt alkaline battery.

Battery included but not connected.

Weight: 10.2 oz. (289 g).
Connections: Two barbed connections for use

with 1/8˝ (3.18 mm) or 3/16˝ (4.76 mm) I.D. tubing
for 477A-1, 477A-2, 477A-3, 477A-4 and 477A-5
only. Two compression fittings for use with 1/8˝
(3.18 mm) I.D. x 1/4˝ (6.35 mm) O.D. tubing for
477A-6 and 477A-7 only.

Series 477A Digital Manometers are ver­satile, hand-held, battery operated manome­ters available in several basic ranges from 0­20 in. w.c. up to 100 psi. All models measure
either positive, negative or differential pres­sures with ±0.10% of full scale accuracy. You
can select from up to seven common English
and metric pressure units so conversions are
not necessary. A memory function allows
storage of up to 40 readings for later recall
and a backlight provides auxiliary lighting for
hard-to-see locations. Also standard are a
hold feature plus both visual and audible over­pressure alarms.

Model

Number

English

Range

Metric
Range

477A-1 0-20.00 in. w.c. 0-4.982 kPa
477A-2 0-40.00 in. w.c. 0-9.96 kPa
477A-3 0-200.0 in. w.c. 0-49.82 kPa
477A-4 0-10.00 psi 0-68.95 kPa
477A-5 0-30.00 psi 0-206.9 kPa
477A-6 0-50.00 psi 0-344.8 kPa
477A-7 0-100.0 psi 0-689.5 kPa

Maximum Pressure

477A-1 3 psi (0.21 bar)
477A-2 3 psi (0.21 bar)
477A-3 15 psi (1.03 bar)
477A-4 30 psi (2.07 bar)
477A-5 60 psi (4.13 bar)
477A-6 100 psi (6.89 bar)
477A-7 200 psi (13.78 bar)

Available Pressure Units:

477A-1 & 477A-2: psi, in. w.c., mm w.c., in.
Hg, mm Hg, Pa, kPa, bar, mbar

477A-3 & 477A-4: psi, in. w.c., mm w.c., in.
Hg, mm Hg, kPa, bar, mbar

477A-5, 477A-6 & 477A-7: psi, in. w.c., in.
Hg, mm Hg, kPa, bar, mbar

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]

Phone: [phone] www.dwyer-inst.com

INSTRUCTIONS
Battery Installation

The unit is shipped with a separate 9 volt alkaline battery which must be installed before
operation. Remove the two screws holding the bottom endcap in place and remove the
endcap. Connect the battery to the enclosed battery clip observing correct polarity. Be
careful not to trap wires between the battery, case or foam pads which retain the battery.
This could make it difficult to install the battery or remove it later for replacement. Be sure
the rubber gasket is properly seated in the gasket channel of the endcap and replace end­cap. Note that the endcap will only fit one way because the holes are slightly off-center.
Place the “Z” shaped wrist strap clip in one of the screw recesses and replace the screws.
Do not overtighten the screws. Attach wrist strap to clip.

When battery replacement becomes necessary, use only a 9 volt alkaline type such as
a Duracell
duty are not recommended because of the increased potential for leakage. Alkaline batter­ies are also a better value because they last up to three times longer in this device.

®

MN1604, Eveready®522 or equivalent. Zinc-carbon types, often labeled Heavy-

On-Off Operation

The on-off control is a toggle function. Press and release the ON/OFF key once to turn
unit on; again to turn it off. If the manometer is left on with no activity for approximately 20
minutes, unit will turn itself off to conserve the battery.

Display Backlight

The Model 477A includes a display backlight to allow use in the dark or in poor lighting con­ditions. Manometer must be switched off before this feature can be activated. Next, press and
hold the ON/OFF key down. After about 1 second the backlight will come on and remain light­ed for approximately 2 minutes after which it will turn itself off to conserve battery life.

Zeroing Pressure Reading

Potential inaccuracy due to temperature effects can be minimized by re-zeroing immediately
before use. To zero the display, vent both ports to atmosphere so no pressure is applied to
either port. Press the ZERO/STORE key and - - - - will be momentarily displayed as zeroing
occurs. Zeroing is not possible when the memory mode is in use. It must be done before select­ing that function.

If the unit is accidently zeroed with pressure applied to one of the ports, the pressure read­ing might display incorrectly. To correct, vent the pressure ports to atmosphere and press the
ZERO/STORE key to zero the unit.

Pressure Connections

To measure single positive pressure, connect tubing to port marked + and vent oppo­site port to atmosphere. To measure differential positive pressure, connect higher positive
pressure to port marked + and lower positive pressure to port marked -. Manometer will
indicate the difference between the two.

Selecting Pressure Units

Up to seven pressure units are available. The display will indicate the current selection.
To change to different units, use the UNITS/LOC key. Each touch will cause an advance to
the next choice. The selected units will remain in memory even when power is shut off. This
way, your preference will always be displayed after the initial selection.

Display Hold

There may be situations where you want to temporarily retain a reading. The Model 477A
includes a Display Hold feature which freezes the current reading and holds it in the display until
cleared. To activate this operation, momentarily press the HOLD/MEMORY key when the pres­sure you want to save is displayed. A HOLD indicator will appear in the display to indicate that
the reading shown is frozen. To return to normal operation, press the HOLD/MEMORY key
again.The HOLD indicator will disappear and the current pressure will again be shown.

Memory Function

A memory function is included in the Model 477A that allows you to store up to 40 pres­sure readings for later review or recording. This feature is especially valuable for making a tra­verse of duct velocity pressures with a Pitot tube or for multipoint pressure measurements. The
readings are stored in non-volatile memory so they will be retained even if the unit is shut off or
the battery is removed.

Storing Pressure Readings

To store a reading, press and hold the HOLD/MEMORY until ST01 is displayed then release
the key. Next, press ZERO/STORE key to save current reading to ST01 memory location. A
beep will sound indicating that the reading has been saved. As each reading is saved, the mem­ory location display will advance to the next number. To resume pressure measurement, press
the HOLD/MEMORY key again. Note that in the memory mode, the display zero function is not
available. To zero the display, you must first exit the memory mode and then press the
ZERO/STORE key.

Viewing Stored Readings - Selecting a Location

To view the contents of memory , pr ess and hold the HOLD/MEMORY until RD01 is displayed
then release the key. Next, press UNITS/LOC to view other memory location. To resume pres­sure measurement, press the HOLD/MEMORY key again.

Clearing Memory

To clear the contents of memory, press and hold the HOLD/MEMORY until CLR is displayed
then release the key. Next, press ZERO/STORE key to clear all previously stored readings.
During this operation - - - - will be displayed. Once memory is cleared, the current pressure will
be displayed.

Exiting Memory Mode

To exit the memory mode press the HOLD/MEMORY key again and the unit will return to

normal operation.

Dampening Function

The dampening feature allows the user to enter a dampening number from 1 to 16 (default
value = 2). Entering a larger number increases the amount of readings that are averaged for
each display update.

In order to access the dampening feature, follow the instructions below:

1. Press and hold the HOLD/MEMORY button. The upper right portion of the LCD scrolls
through a menu selection (HOLD, ST01, RD01, CLR, and DAMP). When “DAMP” is shown,
release the HOLD/MEMORY button. This selects the dampening feature.

2. Once “DAMP” is selected, a number is shown in the upper right portion of the LCD, along
with the current pressure reading. This number is the dampening number. Adjust the number
up by pressing the ZERO/STORE button or down by pressing the UNITS/LOC button. The LCD
update rate slows as the number increases from 1 to 16. Therefore, for best r esults, choose the
smallest number that provides a stable pressure reading.

Once the pressure reading is stable, press and release the HOLD/MEMORY button to store the
dampening value.

Overpressure Alarm

A visual indicator and audible alarm are provided to alert the operator that pressure has
exceeded the operating range of the unit. Exceeding the range will not damage it or affect
calibration as long as the maximum rated pressure is not exceeded. Do not exceed the

maximum rated pressure of the manometer. Doing so will cause permanent damage
to the sensor, may rupture the housing and/or cause injury

. The maximum pressure is

shown on the rear label and on page 1 of these instructions.

Low Battery Indicator

A weak battery can cause improper operation or inaccurate measurements. A low battery
indicator is provided on the display to show when the battery needs replacement. Although the
unit might appear to function and indicate properly, the accuracy of readings cannot be guar­anteed when the LOW BAT indicator is illuminated. Replace the battery with a fr esh one. Do not
leave an exhausted battery in the unit due to potential leakage.

MAINTENANCE

The Series 477A handheld digital manometers are not field repairable and should be returned
if repair is needed (field repair should not be attempted and may void warranty). Be sure to
include a brief description of the problem plus any relevant application notes. Contact customer
service to receive a return goods authorization number before shipping.

Duracell® is a registered trademark of The Gillette Company

®

Everready

©Copyright 2009 Dwyer Instruments, Inc.

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]

is a registered trademark of The Everready Battery Company, Inc.

Printed in U.S.A. 7/09 FR# 02-443239-00 Rev. 3

Phone: [phone] www.dwyer-inst.com