Sub-Metering Natural Gas in a Factory Control Environment using EtherMeters and Rotary Gas Meters

In order to track and minimize utility costs, a growing number of forward-thinking, modern factories have initiated efforts to monitor utility usage in realtime — including electricity, water, and natural gas. And such monitoring does not only occur at the utility-owned meters, but within the factory itself so that a breakdown of the utility costs may be properly assigned to each unit of manufactured item.  Today’s article will focus on an in-factory natural gas monitoring system.

Many factories feature paint and heat-curing operations, which consume massive amounts of natural gas.  Utilizing the tools at its disposal, the modern factory can measure — and optimize — its natural gas consumption within the context of an Allen-Bradley-based FactoryTalk/PLC Ethernet network or Modbus/TCP network.

In order to achieve the monitoring goals, each natural gas consumption point should be equipped with a gas meter, such as a Rotary Gas Meter with solid-state pulse output. The pulse signal is then connected to an EtherMeter, which is networked into the plant’s control Ethernet.  Common rotary gas meter brands include GE^® Dresser^®/Roots^®, Romet^®, Elster^®/American^®, and others.

SCADAmetrics TV Video Illustration: EtherMeter and Rotary Gas Meter.

Each EtherMeter processes the pulses and converts them into real-world measurable quantities: totalization (total cubic feet), and instantaneous rate-of-flow (cubic feet per hour). The EtherMeter has the capability of processing one or two gas meters.

On an Allen-Bradley-based Ethernet network, the EtherMeter emulates a MicroLogix 1100 PLC, so integration into FactoryTalk is a snap. Data requests are formulated as SLC500 EtherNet/IP message instructions — basically as scanning a range of N-registers.  If the control network is based upon Modbus/TCP, then data requests are formed as familiar 40,00x register requests.

Are you interested in learning how the EtherMeter can help your factory sub-meter it’s natural gas, water, and electricity usage? Give us a call… We’ll be glad to help!