CONTROL & MEASUREMENT Pressure gauges go digital

A well monitoring system illustrates how measuring instruments can be integrated into the IIoT

There is no alternative to digitised factories. The biggest challenge here lies in transforming existing plants and processes into an Industrial Internet of Things system. A WIKA project for an oil company in northern Germany, where pressure, temperature and level must be monitored in wells, proves that mechanical measuring instruments can also be integrated into the digital world in this way.

Everything is interconnected. Connectivity is what makes the Internet of Things work. Standardised communication between all devices and systems provides the input for the real added value of digitised processes: this information, together with analysis tools, enables operators to optimise their processes in terms of quality, productivity and costs. However, that is only possible if all process data can be accessed independently of the manufacturer. Suppliers of measuring equipment must therefore offer a standardised method of data exchange across different platforms. Apart from the measured values, this concerns all specific information from connected devices that is required to generate a digital twin and allow more extensive planning and analyses.

The project was triggered by a change in the German Mining Act. The amended version of this act stipulates continuous data acquisition at all extraction points. The policy until now has been for employees to drive to each individual point at intervals, then read off and make a note of the instrument values as well as the water level in the wells – a costly and time-consuming procedure. If an oil field has more than one well, safety features are controlled by means of a process control system – a local solution with no connection to the outside. Once again, a human being has to carry out regular on-the-spot inspections.

In theory, it would be perfectly possible to transmit the data from all extraction points to a central control room via cable. However, laying the necessary cables over such a long distance would have a significant environmental impact and it would not make business sense either.

Cost-effective solution Source: ©iStockphoto

Bidirectional data exchange The idea is that, in future, WIKA customers will be able to purchase a system solution, which is why a central platform with open standards is being developed parallel to IIoT-compatible measuring instruments. Bidirectional data exchange, both with the sensor level (measuring instrument) and with customer systems, will then become a reality. This platform will also be utilised by the oil company whose well monitoring system is being digitised by WIKA at a site in northern Germany.


The uniform concept developed by WIKA for all extraction points complies with all regulations, so that there is no need to have the operating license amended. At the same time, it represents a cost-effective solution for the customer: many oil fields have only a limited operational life remaining and the budget for investments must not be out of proportion. The digitised well monitoring system is economically feasible despite the tight financial constraints.

In the past, exclusively mechanical measuring instruments have been used at the extraction points to obtain data as the basis for plant monitoring. The operator wishes to keep this on-site option alongside online monitoring as an alternative requiring no external power, particularly for pressure and temperature, which are the two most crucial parameters. When the digitised monitoring system is installed, therefore, the existing devices will be replaced with WIKA models from the

“intelliGAUGE” and “intelliTHERM” series, which are designed with both an electrical output (4…20 mA) and an on-site display. On the other hand, the level in the storage tank at the well will in future be recorded using a float switch with a 4…20 mA signal.

Pressure gauge with an integral LoRa module, type PGW23 Source: WIKA picture

All devices are connected to a local gateway in the plant via their electrical outputs. This gateway transmits the data from the measuring points to the central system platform using an LPWAN (Low Power Wide Area Network) wireless standard. In the case of pressure, temperature and level measuring instruments, only a relatively small amount of information per day has to be transmitted. The battery for operating the wireless module has a service life of up to ten years for this reason, so that installation and maintenance costs are reduced to a minimum.

LoRaWAN and MIOTY WIKA generally favours LoRaWAN or MIOTY as the wireless standard for its IIoT devices. Both standards transmit on a public band (868 MHz) that can be used by approved devices without a license. Distances of 30 kilometres or more can be covered in this way,

depending on the topography. The standards are thus also ideal for locations with a weak mobile signal.

LoRaWAN is already well-established in the market. WIKA uses this standard as well, to integrate classic display instruments into digitised processes. The manufacturer’s portfolio will soon include a pressure gauge integrating a type PWG23 LoRa module – the first in a new series of mechanical LPWAN devices. It has a microprocessor that converts the measured value transmitted by the Bourdon tube into a radio signal.

Besides LPWAN solutions, WIKA’s planning also takes account of wireless standards which were integrated by the manufacturer in a previous measurement solution for monitoring decentralised tank plants. Dynamic processes with a large number of measured values must have sufficient bandwidth and power output – in other words, a mains supply – in order to transmit data once a second. Systems are also conceivable where many low power data transmissions are concentrated at a single wireless node and bundled.


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