Honeywell AC-250NXS User Manual page 18

AC520NXS has integrated Valve, which can be operated locally from the optical port from
FieldSense tool or remotely over cellular CAT-M1 network from Connexo or NetSense. The
Valve also operates autonomously by meter when a high pressure or high temperature is
detected by the meter based on configuration.
The current position of the Valve Open/Close is indicated on the Meter LCD screen at the
bottom of the screen in all the main screens by indicating ON/OFF. Valve can be closed when
in it is in ON state, opened when it is in OFF state.
Valve Open Operation:
Caution: The Valve open operation shall not be done whilst meter is pressurized above 2PSIG
differential pressure, if the pressure is higher the valve may be damaged!
When Valve open command is issued in closed state, the meter waits for confirmation from the
user. Once user confirms by pressing the select button, the Valve opens followed by valve
leakage test. During the test, the timer screen is displayed which shows the maximum and
minimum times for completion of the leakage test. After the test is completed, gas flow check
successful message is displayed. In case of gas flow detected during the gas flow check, gas
flow check failed error message will be displayed. The user needs to acknowledge the gas flow
successful/failure screen. After few seconds, "valve open successfully" message is displayed
on the screen in the case of gas flow check success or valve closed successful message is
displayed on the screen in case of gas flow failure. Once Valve is opened/closed successfully,
click Select button to enter the main screen, where a user can see the current valve position
indicated as ON or OFF.
This has 4 possible scenarios in case of valve open:
1. Success with user acknowledgement
2. Failure with user acknowledgement
3. Success without user acknowledgement
4. Failure without user acknowledgement
© Elster American Meter Company LLC – 2020
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