Dwyer instruments, inc, Page 4, Fig. b – Dwyer 490 User Manual

Page 4: Fig. a

Page 4

Printed in U.S.A. 7/09 FR#02-443142-01 Rev. 6

DWYER INSTRUMENTS, INC.

Phone: 219/879-8000 www.dwyer-inst.com

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: [email protected]

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 fresh one. Do not leave an exhausted
battery in the unit due to potential leakage.

Optional 3-Way Valve

For certain hydronic applications it is beneficial to measure the differential pressure with the

assistance of the optional attached 3-way valve. (See Fig. A).

Begin with valve V1 open and valves V2 and V3 closed (See Fig. B). Slowly open valves V2 and

V3. Once the pressure has stabilized and is equal on the high and low side, valve V1 can be closed
and normal operation can proceed.

To ensure proper pressures will be detected by the 490, use the bleed fitting provided with this

valve package (See Fig. A). Before applying pressure to the process connections, turn V1 to the open
position and back off the bleed screw. Next apply pressure. After the flowing liquid is free of bubbles,
retighten the bleed screw. Before taking the 490 offline from the process, open valve V1 then close
valves V2 and V3.

Maintenance
The Series 490 is not field serviceable 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

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

Fig. B

BLEED FITTING

5-1/4

[133.35]

1-21/64

[33.73]

10-1/16

[255.60]

Fig. A

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