Dwyer Instruments 490A-1, 490A-2, 490A-3, 490A-4, 490A-5 Specifications, Installation & Operating Instructions

Series 490A Hydronic Differential Pressure Manometer

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Specifications - Installation & Operating Instructions

Bulletin D-24A

Series 490A Hydronic Differential Pressure Manometer are versatile, hand-held,

battery operated manometers available in several basic ranges for positive or
positive differential pressure measurement and can tolerate most liquid media
compatible with 316LSS. A memory function allows storage of up to 40 readings for
later recall and a backlight provides auxiliary lighting for hard-to-see locations.
Standard are a hold feature and both visual and audible overpressure alarms. A
new feature added to the Series 490A is a field adjustable damping, independent
viewable high/low pressure readings, and low range increased resolution. This
allows the user to choose the level of display averaging rate corresponding to the
fluctuation level common in many applications. A 9 V alkaline battery is included
that provides up to 100 hours of operation.

Model
490A-1
490A-2
490A-3
490A-4
490A-5
490A-6

English
Range

0 to 15 psi
0 to 30 psi
0 to 50 psi
0 to 100 psi
0 to 500 psi
0 to 200 psi

Metric
Range

0 to 103.4 kPa
0 to 206.9 kPa
0 to 344.8 kPa
0 to 689.5 kPa
0 to 3448 kPa
0 to 1379 kPa

Maximum
Pressure

30 psi (2.7 bar)
60 psi (4.13 bar)
100 psi (6.89 bar)
200 psi (13.78 bar)
1000 psi (68.9 bar)
400 psi (27.57 bar)

Available Engineering Units

psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in
psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in
psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in
psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in
psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in
psi, in w.c., in Hg, cm w.c., mm Hg, kPa, hPa, mbar, bar, oz/in

SPECIFICATIONS
Service: Compatible gases & liquids.
Wetted Materials: 316 SS; -3V option: 316LSS, Buna-N, silicone, grease, PTFE,

brass 360, copper, reinforced acetal copolymer; -HKIT option: 316LSS, PTFE,
brass, copper.
Accuracy: ±0.5% FS from 60 to 78°F (15.6 to 25.6°C); ±1.5% FS from 32 to 60°F
and 78 to 104°F (0 to 15.6°C and 25.6 to 40°C).

Pressure Hysteresis: ±0.1% FS.
Pressure Limits: See chart
Temperature Limits: Operating: 0 to 140°F (-17.8 to 60°C); Process with -HKIT

option: -20 to 180°F (-29 to 82°C); Storage: -4 to 176°F (-20 to 80°C).

Display: 4-digit LCD (.425˝ H x .234˝ W digits).
Resolution: See chart.
Process Connections: Two 1/8˝ (3.18 mm) female NPT; -HKIT option: Two 1/4˝

male 45° flare fittings.
Power Requirements: 9 V alkaline battery, installed non-functional, user
replaceable.

Weight: 14.1 oz (400 g); -HKIT option: 3.6 lb (1.63 kg).
Agency Approvals: CE.

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ATTERY INSTALLATION

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he unit is shipped with a separate 9 volt alkaline battery which must be installed

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efore operation. Remove the two screws holding the bottom endcap in place and

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emove the endcap. Connect the battery to the enclosed battery clip, making sure

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to observe 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 that the rubber gasket is properly seated

n the gasket channel of the endcap and replace endcap. Note that the endcap will

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nly fit one way because the holes are slightly off-center. Place the Z shaped wrist

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trap clip in one of the screw recesses and replace the screws. Do not over tighten

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he screws. Attach the wrist strap to the clip. Note: On –HKIT option 490A, the

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rubber boot will have to be pulled back to have access to the battery compartment.

AUTOMATIC RESOLUTION ADJUSTMENT

For all ranges, the series 490A will automatically move the decimal place one point

o the left when reading in the bottom 10% of its calibrated range. This allows the

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ser to gain a higher resolution reading for lower static or differential pressure

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eadings.

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ELECTING PRESSURE UNITS

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Up to seven pressure units are available. The display will indicate the current
selection. To change to different units, use the UNITS/LOC button. Each press of
the button will cause an advance to the next choice. The selected units will remain

n the memory even when the power is shut off. This way, the user preferences will

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lways be displayed after the initial selection.

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When battery replacement becomes necessary, use only a 9 volt alkaline type such

s a Duracell

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abeled heavy-duty are not recommended because of the increased potential for

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eakage. Alkaline batteries are also a better value because they last up to three

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times longer in this device.

Low Battery Indicator

A weak battery can cause improper operation or inaccurate measurements. A low

attery indicator is provided on the display to show when the battery needs

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eplacement.

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AT indicator is illuminated. Replace the battery with a new one. Do not leave an

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xhausted battery in the unit due to potential leakage.

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N-OFF OPERATION

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Press the ON/OFF button once to turn the unit on. Once on, press the ON/OFF
button for more than 5 seconds to turn the unit off. If the manometer is left on with
no activity for approximately 20 minutes, the unit will turn itself off to conserve the
battery.

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 the atmosphere so
no pressure is applied to either port. Press the ZERO/STORE button 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 accidentally 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 button to zero the unit.

BACKLIGHT

The Model 490A includes a display backlight to allow use in the dark or in poor
lighting conditions. Pressing the ON/OFF button toggles the backlight on or off. With
the 490A on, press the ON/OFF button to toggle the backlight on or off. The
backlight will remain lit for approximately 2 minutes after which it will turn itself off
to conserve battery life.

OTICE

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Although the unit might appear to function and indicate properly,
the accuracy of readings cannot be guaranteed when the LOW

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22, or equivalent. Zinc-carbon types, often

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ISPLAY HOLD

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In situations where a reading needs to be temporarily retained, the Model 490A
includes a display hold feature which freezes the current reading and holds it on
the display until it is cleared. To activate this operation, press the HOLD/MEMORY

utton when the desired pressure is displayed. A HOLD indicator will appear on the

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isplay to indicate that the reading shown is frozen. To return to normal operation,

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ress the HOLD/MEMORY button again. The HOLD indicator will disappear and

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the current pressure will be shown.

MEMORY FUNCTION

A memory function is included in the Model 490A that allows users to store up to 40

ressure readings for later review or recording. The readings are stored in non-

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olatile memory so they will be retained even if the unit is shut off or the battery is

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emoved.

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toring Pressure Readings

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o store a reading, press and hold the HOLD/MEMORY button until ST01 displayed.

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Next, press the ZERO/STORE button to safe the current reading to the 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 button again. Note
that in the memory mode, the display zero function is not available. To zero the
display, exit the memory mode and then press the ZERO/STORE button.

Viewing Stored Readings – Selecting a Location

To view the contents of the memory, press and hold the HOLD/MEMORY button
until RD01 is displayed. Next, press UNITS/LOC to view other memory locations.
To resume pressure measurement, press the HOLD/MEMORY button again.

Clearing Memory

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

Exiting Memory Mode

To exit the memory mode, press the HOLD/MEMORY button again and the unit will
return to normal operation.

PRESSURE CONNECTION

Measuring Single Pressure

To measure single positive pressure, connect the tubing to the port marked “High
Pressure” and vent the opposite port to the atmosphere.

Measuring Differential Pressure

To measure differential pressure, connect the higher positive pressure to the port
marked “High Pressure” and the lower positive pressure to the port marked “Low
Pressure”. The manometer will indicate the difference between the two.

Overpressure Alarm

A visual indicator and audible alarm are provided to alert the user 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. The
maximum pressure for all units is shown on the rear label and on page 1 of these
instructions.

CAUTION

rupture the housing, and/or cause personal injury.

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Do not exceed the maximum rated pressure of the manometer.
Doing so will cause permanent damage to the sensor, may

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