CASE STUDY: GAS VOLUME CONVERTER

Intelligent devices for the gas market using pressure sensors and platinum temperature sensors from JUMO

Gas Meter Market Development - Forecasts: according to analysis, the global smart gas meter market is estimated to reach USD 2.5 billion by 2026, at a compound annual growth rate of 4.7%, from an estimated USD 2.0 billion in 2021. A key driver for the smart gas meter market is the global digitisation of distribution networks and increased investment in smart grid technologies for measurement and subsequent data analysis.

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Measurement data collection and analysis

Industry is well into the Industry 4.0 revolution, one of the pillars of which is the Internet of Things (IoT). This is a system of interconnected objects and devices that transmit information digitally. The growing use of the Internet of Things has significantly increased digitisation in many industries, which include gas and electricity. IoT communication networks enable network operators and energy companies to provide modern energy services. Digitisation also extends to hybrid cloud infrastructure, which will allow big data and IoT capabilities to be used to manage networks in an increasingly flexible and efficient manner.

Smart technologies in the gas market

Data collected from a smart metering device can be used for a variety of analyses, with one of the primary tasks being to monitor gas consumer behaviour. Smart grids are key technologies that have modernised gas networks, providing utilities and consumers with information to efficiently manage their gas consumption. Energy companies around the world are increasingly investing in smart grid technologies that enable them to automatically monitor and control gas consumption, develop new business models, and reduce outages and response times in the event of natural hazards. An important aspect in light of these assumptions is reliable gas volume information from a specialised gas volume converter.

What is a gas volume converter?

A gas volume converter is an external device connected to the gas meter which calculates, sums and determines the incremental gas volume measured by the gas meter under conditions corresponding to the base conditions. Gas volume converters are used for commercial settlements of wholesale gas volumes. Base conditions are gas conditions to which the volume of measured gas is converted (e.g. base temperature and base pressure). Base conditions are assumed to be a base temperature selected from the following values: 0°C, 15ׄ°C, 20°C and a base pressure of 101.325 kPa, to which the volume of gas measured at the measurement conditions is converted. The measurement conditions are the state of the gas, the volume of which must be measured at the measurement point and for this purpose it is necessary to measure the temperature and pressure of the measured gas, which is carried out by the volume converter with the help of appropriate temperature and pressure sensors. For this purpose, pressure sensors scaled to absolute ranges and temperature sensors based on Pt100 or Pt1000 temperature sensors are used. A distinction is made between the following types of volume conversion devices:

- those that convert gas volume only from the measuring temperature to the volume at the base temperature,

- Gas volume converters converting the volume of gas from the metering pressure to the volume at base pressure only,

- volume converters converting the volume of gas from the metering temperature and pressure to the volume at base temperature and pressure.

Design of an intelligent gas volume converter

Modern smart gas volume converters have a battery power supply and an integrated GSM modem. They provide volume correction to base conditions from rotary, turbine and ultrasonic gas meters at gas reduction and metering stations. As they are high-class measuring and settlement devices, they fully meet the requirements of the MID directive. In order to measure pressure and temperature in metering conditions, it is necessary to use reliable top-class devices with a high accuracy and appropriately selected measuring range. This is where JUMO pressure transmitters and temperature sensors come into their own.

JUMO pressure cells (measuring bridges) and Pt100, Pt1000 platinum thermometric resistors

JUMO is a world leader in the manufacture of a wide range of measuring and control equipment, including the above-mentioned temperature sensors and pressure transmitters with flat measuring cells used for example in gas volume calculators. Manufacturers of these devices often integrate in the production process elements that process pressure and temperature, such as cells (pressure bridges), which are the measuring heart of a pressure transmitter, and Pt100 thermometric platinum resistors, which are analogously the heart of a temperature sensor.

Design and types of platinum temperture sensors

The JUMO product range includes a wide range of platinum thermoresistive temperature sensors of various nominal values, e.g. Pt100 and Pt1000. With an annual production of several million measuring resistors, we are one of the world's leading suppliers. High-quality platinum temperature sensors with thin-film technology guarantee excellent accuracy, long-term stability and high flexibility. They also meet specific application requirements such as the highest tolerance class and have high long-term stability. Thin-film sensors are created by sputtering a layer of platinum, which functions as an active layer applied to a ceramic carrier by sputtering and then formed into a meandering pattern by photo lithography.

Resistors of this type form the main part of temperature sensors used in industry. They are placed in stainless steel sheaths, which protect this type of sensors from external influences such as pressure. The result is a resistance that protects the temperature sensor from pressures up to 450 bar relative pressure.


Thermistor with connection terminals

How an OEM pressure sensor is built - silicon structures

For optimal measurement, OEM pressure sensors are built as thin-film piezoresistive silicon structures (pressure bridges/cells) with an amplified output, e.g. 3.5k Ohm or 6k Ohm, as well as digital pressure transmitters with an I2C output, in which the zero point can be adjusted. All flat cell sensors can be manufactured according to customer specifications for the specified measuring range. For example, it is possible to manufacture a calibrated high accuracy structure with an integrated temperature sensor for medium temperature compensation or a version without temperature sensor, where the calibration and balancing of the Wheatstone bridge is carried out by the customer himself.

The design of the Wheatstone bridge ensures the compensation of the measuring system. By connecting two voltage dividers in parallel, an unknown resistance value resulting from the ambient temperature is determined. When the circuit is brought into equilibrium, it compensates for the measured pressure value and thus achieves a high accuracy of the pressure sensor under various ambient temperature conditions. The pressure sensor can also be supplied welded to an available process connection made of stainless steel, e.g. G1/4" or G1/2". A pressure sensor that is precisely welded into the mechanical part of the process connection, i.e. the assembly part of the gas pipeline, requires special machinery. JUMO, with its automated production lines, is able to provide the above mentioned solution according to customer requirements and supply the pressure sensor in OEM version.


Pressure cell with connections

JUMO in the world of gas technology

The dynamic development of the gas distribution market has led to the development of intelligent technologies such as gas volume converters that, in line with the IoT trend, are equipped with measurement data loggers and remote communication and are characterised by the highest billing accuracy. Manufacturers of such advanced professional electronics require cooperation at the highest level with reliable and proven suppliers of automation components like JUMO, hence products such as pressure cells and Pt100 thermometric resistors are so highly valued among our customers.


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