Panametrics XGM868i DigitalFlow Gas Ultrasonic Flow Transmitter

Overview

The Panametrics XGM868i (DigitalFlow XGM868i) is a compact ultrasonic flow transmitter designed to measure the flow of virtually any gas. Where larger console-based systems separate the electronics from the pipe, the XGM868i packages every electronic component in a single explosion-proof head that is installed right at the measurement point. That arrangement simplifies transducer wiring, reduces installation cost and gives a low-cost route to ultrasonic accuracy on fuel gas, process gas and waste gas lines.

Seven Star LLC supplies the Panametrics XGM868i with transducers and flowcells to process plants, power stations and utilities across the Sultanate of Oman and the GCC, backed by engineering support in Muscat. Regional users typically choose it for fuel gas to turbines and heaters, plant air and nitrogen headers, and allocation points where a non-intrusive, drift-free gas meter is preferred over orifice plates or turbine meters.

Operating Principle

Like other DigitalFlow instruments, the Panametrics XGM868i uses transit-time ultrasonic measurement. Two wetted transducers face each other across the pipe at an angle; each acts in turn as transmitter and receiver. Sound travelling downstream reaches its receiver slightly faster than sound travelling upstream, and that time difference is proportional to the average gas velocity along the path. The transmitter multiplies velocity by the pipe area to obtain actual volumetric flow and, with temperature and pressure inputs, reports standard volume and mass flow as well as totalised flow.

Because the path of the Panametrics XGM868i is open bore there is nothing in the gas stream to obstruct flow, collect debris or erode. The meter therefore creates no permanent pressure drop, an important saving on low-pressure gas systems where every millibar costs compressor power. Its sealed metal transducers resist the stress of thermal expansion cycles, and Panametrics specifies a bidirectional range of -46 to 46 m/s (-150 to 150 ft/s) with an overall rangeability of 1500:1, assuming a fully developed profile of around 20 diameters upstream and 10 downstream. Panametrics notes that the stated accuracy can be reached with a total straight run as short as 10 diameters when flow profile correction is applied, which helps on crowded skids and compact plant layouts.

Engineering Design of the Panametrics XGM868i

The Panametrics XGM868i head is an epoxy-coated aluminium Type 4X/IP66 enclosure rated for Class I, Division 1, Groups B, C and D and flameproof II 2 GD EEx d IIC T5 under ATEX, with a stainless steel version as an option. It measures about 208 × 168 mm and weighs 4.5 kg. An optional two-line, 16-character backlit LCD can scroll up to four parameters, and a six-button keypad gives full programming without opening the enclosure in the field.

The standard Panametrics XGM868i is single channel; the optional two-channel version measures two paths on one pipe for better accuracy or one path on two separate pipes. Power is 100 to 240 VAC or 12 to 28 VDC at 20 W maximum. Two isolated 0/4-20 mA outputs are standard, and option cards add further outputs, 4-20 mA inputs with 24 VDC loop power, RTD inputs, pulse or frequency outputs and alarm relays. Digital communication includes RS232 as standard with RS485, Modbus RS485 or TCP, Ethernet, OPC server and Foundation Fieldbus options.

Key Features

Engineers specify the Panametrics XGM868i for the following characteristics:

• Economical ultrasonic gas measurement in a compact transmitter mounted at the pipe.
• No moving parts and no pressure drop, giving low operating and maintenance cost.
• Wide rangeability of 1500:1 for applications with large flow swings.
• Tolerance to dirty gas streams that would foul differential pressure or turbine meters.
• Two-path option for maximum accuracy, typically ±1.5% of velocity versus ±2.0% for one path.
• Wetted titanium transducers rated to 187 bar standard and 240 bar optional, with high-temperature designs from -190 to 450 °C overall.
• Optional data logging of more than 150,000 flow points.
• Repeatability of ±0.2% to 0.5% of reading.

Industrial Applications

Panametrics lists hydrocarbon gases, vent gases, biogases, digester gases, fuel gases, waste gases, incinerator air flow, vapour recovery and stack gases among typical services. In practice the Panametrics XGM868i is used for fuel gas consumption on gas turbines and fired heaters, plant-wide energy accounting, compressed air and nitrogen headers, and biogas metering at sewage treatment works where wet, dirty gas quickly degrades mechanical meters.

For operators in Oman, typical installations include gas-fired power and desalination plants on the Batinah coast, fuel gas networks inside refineries and petrochemical complexes in Sohar, and wastewater treatment plants recovering biogas. Seven Star LLC supplies the Panametrics XGM868i with suitable transducers, flowcells or cold-tap hardware and engineering support in Muscat. Users comparing options often review the Panametrics DigitalFlow GM868 gas flowmeter for console-type installations, and for liquid lines the Panametrics XMT1000 transmitter; gas moisture can be monitored alongside with the HygroPro II moisture transmitter.

Technical Specifications

Key Panametrics XGM868i figures from datasheet PANA061DS Rev. 3:

How to Order

To receive a quotation for the Panametrics XGM868i, send the gas type, line size, pressure and temperature range, required area classification and output protocol. Seven Star LLC will configure the transmitter and transducers, confirm availability and lead time and provide engineering support from Muscat to customers throughout Oman and the GCC. Download the technical datasheet from this page for full details.