Honeywell AC-250NXS User manual

AC-250NXS INSTALLATION AND USER MANUAL
Rev. 1.1 |
April 2022

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DISCLAIMER
This document contains Honeywell proprietary information.
Information contained herein is to be used solely for the purpose submitted, and
no part of this document or its contents shall be reproduced, published, or
disclosed to a third party without the express permission of Honeywell
International Sàrl.
While this information is presented in good faith and believed to be accurate,
Honeywell disclaims the implied warranties of merchantability and fitness for a
purpose and makes no express warranties except as may be stated in its written
agreement with and for its customer.
In no event is Honeywell liable to anyone for any direct, special, or consequential
damages. The information and specifications in this document are subject to
change without notice.
Copyright 2022- Honeywell International Inc.
AC-250NXS is Copyright 2022- Honeywell International Inc.

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Table of Contents
ABOUT THIS GUIDE ...........................................................................................................................................................6
Scope ..................................................................................................................................................................... 6
Revision history ..................................................................................................................................................................... 6
Intended audience ..................................................................................................................................................................... 6
Related documents ..................................................................................................................................................................... 6
PRODUCT OVERVIEW ...........................................................................................................................................................7
PRODUCT SPECIFICATIONS ...........................................................................................................................................................8
AC-250NXS valve features ..................................................................................................................................................................... 9
PRODUCT COMPONENTS ........................................................................................................................................................ 10
SAFETY AND COMPLIANCE INFORMATION ............................................................................................................................................. 12
Liability .................................................................................................................................................................. 12
RF exposure .................................................................................................................................................................. 12
Safety instructions .................................................................................................................................................................. 12
Conversion, spare parts .......................................................................................................................................................13
Electromagnetic compatibility ..........................................................................................................................................13
Lithium battery .......................................................................................................................................................13
Electrostatic discharge .......................................................................................................................................................13
FCC Compliance Statements.............................................................................................................................................14
AC-250NXS GAS METER SPECIFICATIONS......................................................................................................................................... 15
CHECKING THE USAGE IN POTENTIALLY EXPLOSIVE ATMOSPHERES ........................................................................................ 17
Marking .................................................................................................................................................................. 17
Use as follows .......................................................................................................................................................17
AUTONOMOUS VALVE SHUTOFF CONFIGURATION ............................................................................................................................. 18
ALERT NOTIFICATION CONFIGURATION .................................................................................................................................................. 19
INTEGRATED CAT-M1 COMMUNICATIONS MODULE......................................................................................................................... 20
Install the AC-250NXS Gas Meter......................................................................................................................................................... 21
AC-250NXS GAS METER LCD OPERATION....................................................................................................................................... 24
Operating the electronic index ............................................................................................................................................................... 24
User keys, selection key and symbols.................................................................................................................................................. 24
Navigating within the menu .................................................................................................................................................................. 28
Menu overview .................................................................................................................................................................. 29
Main Menu screen features: .................................................................................................................................................................. 30
Service Menu screen features:................................................................................................................................................................ 33

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Volume Data Integer configuration...................................................................................................................................................... 38
Valve operation .................................................................................................................................................................. 39
Valve Opening operation .................................................................................................................................................................. 39
Command scenario .................................................................................................................................................................. 40
Valve error .................................................................................................................................................................. 41
Valve Closure Operation .................................................................................................................................................................. 42
Flow test .................................................................................................................................................................. 43
SECURITY ........................................................................................................................................................ 45
Privacy .................................................................................................................................................................. 45
Key management .................................................................................................................................................................. 45
Network recommendations .................................................................................................................................................................. 46
Meter firmware upgrades .................................................................................................................................................................. 46
Server upgrade: .................................................................................................................................................................. 46
Safe disposal of consumption data ..................................................................................................................................................... 46
Software licenses .................................................................................................................................................................. 46
Report security vulnerability .................................................................................................................................................................. 46

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Abbreviations:
PTW - Paging time window
EDRX - Extended Discontinuous Reception
MDC - Meter Data Collection
MDM - Meter Data Management
OTA - Over the Air
OEM - Original equipment manufacturer
ESD - Electrostatic Discharge
FCC - Federal Communications Commission
CFH - Cubic feet per hour
PCB - Printed Curcuit Board
HES - Head-End system
AMI - Advanced Metering Infrastructure

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About this guide
Scope
This manual is a guide to the features, specification, installation and user manual
of smart gas meter.
Revision history
Revision
Supported
Release
Date
Description
1.1
R200
April 2022
Initial release
Intended audience
This guide is primarily intended for Honeywell field personnel who install and
configure the product.
Related documents
The following list identifies publications that may contain information relevant to
the information in this document.

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Product Overview
The Honeywell American Meter AC-
250NX class meter was designed
residential compact metering, delivering
high performance measurement at an
economical price. Being one of the
smallest and lightest diaphragm gas
meters this meter can be used anywhere,
AC-250NXS is reliable, accurate, easy to
install and fits in tighter spaces, such as
meter manifolds in apartment complexes.
More than 100 million meters based on
this measurement cartridge design have
been sold worldwide. The AC-250NXS is available with built-in temperature
conversions for accurate measurements. An integrated CAT-M1 cellular
communication module enables automatic meter readings to be updated to
utilities multiple times in a day to have real-time analysis into the gas
consumption and meter health.

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Product Specifications
•Reliable proven diaphragm measuring unit with over 100M installed base.
•Built-in temperature compensation for high accuracy of the measurements.
•15 years of battery life with integrated 2 D-Size batteries when using the meter at
recommended operating parameters.
•Reliable communication with Head End System (> 99% communication success, when using
recommended operating parameters).
•Public cellular CAT-M1 communications module (Always on functionality).
•Part of Honeywell connected utilities eco system, integrated into Honeywell Connexo MDC
and MDM system.
•Honeywell MeterSense maintenance handheld tools for easy maintenance of the device via
optical communication.
•Highly secured with end-to-end industry standard encryption and authentication methods.
•Honeywell SNAP prover integration with electronic accuracy adjustment.
•Safety features:
⎯Intrinsically safe (class I, division 1, group D, T1).
⎯Reliable, bubble-tight valve.
⎯Autonomous shut off based on high pressure, high temperature, and tamper.
⎯Safety alert to Head End system during valve closure/opening.
⎯High/Reverse flow rate alarm and Autonomous shutoff.
⎯Remote valve shut off.
⎯High-Response Mode (communicates every 15 minutes during emergency situations
like High Pressure, High Temperature, High Flow or Valve closure).
•In-field changeable battery.
•Volume, pressure, temperature, and meter status reporting for Head End analytics.
•OTA firmware upgrades for communication and metrology.
•Local standardized optical service port for in-field diagnosis, valve operation and re-
calibration.

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AC-250NXS valve features
AC-250NXS includes an integrated valve with the following features:
1. Enables remote disconnection of the gas supply.
2. Enables automatic disconnection of the gas supply on high pressure,
temperature, flow, Reverse flow events.
3. Protected against unintentional opening of the valve.
4. Re-enable gas only once the customer’s gas appliances are closed.
5. No energy consumed when the valve is closed.
6. Low energy consumption during activation.
7. Detection of open and closed positions.
8. Configurable valve autonomous shut-off thresholds during High gas
Pressure or Temperature.

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Product Components
The AC-250NXS Gas Meter features these components in a compact meter.
1. AC-250NXS Gas Meter index
a. The index contains the Cat-M1 communications module, two batteries,
one replaceable.
b. The LCD provides a visual display of consumption, alarm messages,
and status information.
2. An internal shutoff-valve.
3. Diaphragm measuring unit.
4. Integrated metrological unit with optical pickup.
5. Die cast aluminum case.
6. Steel bosses.
S. No
Description
S. No
Description
1.
Serial number bar code
Format: code 128 ISO/IEC 15417
5.
Left navigation button
2.
Meter serial number
6.
Optical probe connection

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S. No
Description
S. No
Description
3.
Display
7.
Battery cover seal
4.
Select button
8.
Battery cover

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Safety and Compliance Information
Please read through these instructions carefully before installing or operating the
AC-250NXS gas meter. This unit must be installed and commissioned in
accordance with the regulations and standards for your utility.
Liability
Elster American Meter Company and its parent Honeywell will not be liable for
damage resulting from non-observance of the instructions and non-compliant
use.
RF exposure
This device is intended for fixed use only (not portable). This device complies with
radiation exposure limits set for uncontrolled environments. A distance of 20 cm /
7.8 inches must be maintained between the device and the user's body and the
body of a nearby person.
The meter must not be installed or operated in close proximity with any other
antenna or transmitter.
Safety instructions
Information that is relevant for safety is indicated in the instructions as follows:
DANGER
Indicates potentially fatal situations.
WARNING
Indicates possible danger to life and limb.
CAUTION
Indicates possible material damage.
Indicates correct disposal.
All interventions may only be carried out by qualified gas technicians. Electrical
interventions may only be carried out by qualified electricians.
NOTE: A QUALIFIED TECHNICIAN IS A PERSON WHO IS TRAINED TO PERFORM CERTAIN TASKS
WITH STANDARDS UNDER SAFETY AUTHORITY.

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General Warnings and compliances
Conversion, spare parts
Use only OEM spare parts. Changes or modifications not expressly
approved by the manufacturer can be void the express limited
warranty and the user's right to operate the equipment.
Electromagnetic compatibility
Operation of the product is subject to the following two conditions:
1. this device may not cause harmful interference, and
2. this device may in certain circumstances be susceptible to interference
received, including interference that may cause undesired operation.
Lithium battery
The device contains non-rechargeable Lithium batteries that are potentially
hazardous and can present a serious FIRE HAZARD if damaged, defective, or
improperly used.
WARNING:
•Do not recharge the batteries as they are non-rechargeable. The battery must be disposed
carefully according to applicable rules and regulations after they are used as seeping into ground
water may put human health at risk.
•Battery connectors are lockable, while removing they must be pressed and detached.
Electrostatic discharge
The device contains parts and assemblies susceptible to damage by ESD. Before
installing the device, discharge the electrostatic buildup through a properly
grounded metal surface before touching the device during installation or
maintenance.

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FCC Compliance Statements
This device complies with Part 15 of the FCC rules. Operation is subject to the
following two conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received including interference
that may cause undesired operation of this device.
This equipment has been tested and found to comply within the limits for a Class
B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed
to provide reasonable protection against harmful interference in a residential
installation. This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with these instructions, may
cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this
equipment does cause harmful interference to radio or television reception, the
user is encouraged to try to correct the interference by one or more of the
following measures:
1. Reorient or relocate the receiving antenna
2. Increase the separation between the equipment and the receiver
3. Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected
4. Consult the dealer or an experienced radio/TV technician for assistance
If you experience trouble with this equipment, please contact Customer Service at
Honeywell Elster American Meter. Do not attempt to repair this equipment
yourself unless you are replacing the entire module. Any such modifications could
void the user’s authority to operate the equipment and voids the manufacturer’s
warranty.

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AC-250NXS Gas Meter Specifications
Specification
Value
Flow rate
250 CFH at 0.5in w.c.
Measurement principle
Molded, convoluted diaphragm
Safety
Intrinsically safe (class I, division 1, group D, T1)
Meter type
Temperature Compensated (TC) or Non-Temperature Compensated
(NTC)
Meter Maximum Allowable
Operating Pressure (MAOP)
5 PSIG (345 mbar)
LCD displayed units
CCF (100 x cubic foot)
LCD resolution
0000.001 CCF, 00000.001 CCF, 000000.001 CCF
Valve
Gas tightness: meets or exceeds ASME B16.33 section 4.2, leakage
rate at max 2PSIG diff. pressure
Case
Die-cast aluminum case
Weight
12 lbs.
Gas type
Natural gas
EN437- Type H,E,L
Reference gases G20, G21, G23, G25, G26, G2
Connection sizes
10 LT, 20 LT, 30 LT, 1” PITTS, 1” Sprague
Operating temperature ratings
Measurement -30° F (-34° C) to +140° F (60° C)
Valve and Display -13° F (-25° C) to +131° F (55° C)
Index -40° F (-40° C) to +158° F (70° C)
Storage temperature
-40° F (-40° C) to +158° F (70° C)

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Specification
Value
Battery information
2 Lithium Thionyl Chloride 'D' cell batteries, one battery is replaceable
Battery life
15 years for both metrology and index communication (under
recommended operating conditions)
Standards
Designed in compliance with ANSI B109.1
Regulatory
This device complies with Part 15 of the FCC rules.
FCC ID: 2AAGMGM02S
Component materials
Single coat polyester

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Checking the Usage in Potentially Explosive Atmospheres
Marking
Use as follows
•Class I: Flammable gases or vapors may be present.
•Division 1: Ignitable concentrations of hazards exist under normal operation conditions
and/or where the hazard is caused by frequent maintenance or repair work or frequent
equipment failure.
•Group D/ IIA: Explosion group for gases (acetone, ammonia, benzene, butane, ethanol,
gasoline, hexane, methane, methanol, methane, naphtha, natural gas, propane and toluene).
•T1: maximal surface temperature (842°F).
•Ta: Ambient temperature.
•Zone 0: The device may be used in a place in which an explosive atmosphere is continually
present.
•Ex: Explosion protection.
•AEx: Explosion protection approved to US standards.
•ia: Type of ignition protection: intrinsic safety for zone 0.
•Ga: Equipment protection level for zone 0.

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Autonomous Valve Shutoff Configuration
The AC-250NXS valve can be configured for autonomous shutoff the during
following events:
1. High gas pressure is detected, exceeding the configured threshold value for
a set duration of time. The high-pressure threshold can be configured by
utilities.
2. High gas temperature is detected, exceeding the configured threshold value
for a set duration of time. The high temperature threshold can be configured
by utilities.
3. High/Reverse gas flow is detected, exceeding the configured threshold
value for a set duration of time. The high/Reverse flow threshold can be
configured by utilities.
4. Tamper event is detected (unauthorized opening of service cover or
unauthorized battery removal).
The autonomous shutoff can be disabled for a specific event by the operating
utility.
For example, utilities can disable the autonomous shutoff valve closure when a
tamper event is detected, and it can instead configure the unit to only report an
alert to the HES.
THE HEAD-END SYSTEM IS THE HARDWARE AND SOFTWARE THAT RECEIVES THE STREAM OF
METER DATA BROUGHT BACK TO THE UTILITY THROUGH THE AMI.

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Alert Notification Configuration
The AC-250NXS has multiple alert notifications reported to Head End System.
The following are some of the critical alert notifications:
1. High gas pressure is detected and returned to normal.
2. High gas temperature is detected and returned to normal.
3. High/Reverse gas flow rate is detected and returned to normal.
4. Tamper event is detected.
5. Reverse Flow detected and returned to normal.
6. Valve Opened or Valve Closed.
Most of the above notifications can be disabled by the utilities –as they can
configure the device to report only notifications which are of prime interest.

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Integrated CAT-M1 communications module
The AC-250NXS includes an integrated CAT-M1 communications module, which
enables the meter to connect to public CAT-M1 cellular networks as scheduled,
during the installation and commissioning phase (typically once every 12 hours).
During communication, the device sends hourly interval data, daily consumptions
readings, meter and valve diagnostics to the Head End System.
When an alert such as high gas pressure or tamper condition is detected, the
meter immediately sends an alert to the Head End System within 15-seconds of
detecting the abnormal condition.
The device is incorporated with the ALWAYS ON feature which enables it to
receive requests from the Head End System. Apart from the device-initiated
communications, the Head End System can also trigger data communications
whenever necessary. This enables the remote valve shut off to be serviced
immediately to make sure of the safety in case of any emergency. The Head End
System can open the valve when the environment is clear, provided a person must
acknowledge physically when the valve is opened. The device can be reachable at
different time intervals –this can be configurable via the EDRX parameters.