DefProc’s latest collaboration with Northern Gas Networks (NGN) has led to the creation of a Smart Gas Pressure Sensor. Designed to detect low-pressure in consumer homes, the device can be used with natural gas, hydrogen and a blended supply. If the pressure goes below the low threshold point (17 mbar), the device activates a shut-off valve to close the customer’s gas supply and assist in protecting the wider network.

Project background

As part of its Hydrogen Strategy, the UK Government is supporting research, development and testing projects to determine the feasibility of using hydrogen as an alternative to natural gas for heating. Hydrogen has a lower density and energy content than natural gas, so it needs a higher flow rate. As the UK gas networks run at low pressure, maintaining supply pressure is crucial for both consumers and equipment. 

In the event of an incident on the network, a reduction in gas supply pressure could affect the security of supply and delivery of gas at a satisfactory pressure. In extreme conditions, the gas supply is isolated to allow the network to recover. Reestablishing supply is costly and time-consuming as it relies on gaining access to each property multiple times. To solve this problem, NGN wanted a device that could detect low pressure at the point of supply in consumer properties and activate a shut-off valve to isolate the gas supply.

Designing a gas pressure monitoring solution 

We approached each design requirement with a comprehensive assessment framework to ensure our decisions aligned with NGN’s goals and expectations. During the research phase, we compiled a detailed analysis to identify risks, mitigations, and alternative solutions for each requirement. This process allowed NGN to understand the rationale behind each design decision, fostering transparency and providing them with a clear view of how each choice would impact the functionality, durability, and user experience of the device. By proactively addressing potential challenges, we aim to build confidence in the design path while aligning with the client’s vision.

We explored several different pressure sensors. The sensor we selected was compatible with hydrogen and natural gas, allowed pressure sensing up to 2 bar, well-suited for low-power applications and could be integrated with the device’s electronics.

Decisions for the valve included selecting the type of ball valve, how to power the valve motor drive and its positioning within the size-restricted device.

Any material used for the device had to be compatible with hydrogen and natural gas.

Input from an external power source (mains) was preferred over an internal battery. However, the voltage input needed to be close to the operating voltage to minimise losses. With this in mind, a USB port was added to power the device alongside a silicone insert plug to prevent dust ingress when the socket is not in use.

The initial choice was either primary (non-rechargeable) or secondary (rechargeable) battery type. Due to the self-discharge present in secondary batteries, and the design requirement for multi-year use, primary batteries offered the most suitable energy storage. The battery will offer power backup in the event of a power loss. The device will also send an alert to notify the gas network about a mains power outage.

All the onboard functions of the device are controlled by the microcontroller. We selected an Arm Cortex M0+ because it is compatible with Arduino and is designed for long-life, battery-powered applications.

LoRaWAN was chosen for the device’s connectivity. It offers low power, security and good signal penetration through walls and enclosed spaces. This is important if the device is to run for a long time without human intervention. 

It was necessary to indicate the valve’s status (open/closed) to local users. However, the requirement for the device to be low-power and long-life meant minimising energy consumption. As a result, the LED emits periodic short flashes to indicate the operating state.

The device has to fit within the limited volume between the property’s emergency control valve (ECV) and the gas meter. The layout of the meter boxes at NGN’s Futures Close homes was used as a reference.

The data from the LoRaWAN application is forwarded securely to a server. The collected data is stored in a database specifically designed for storing sensor readings against a timestamp. The database’s dashboard can display current and historical data and includes an alert system if a device drops below the 17 mbar threshold.

As the device will be fitted in consumer meter boxes, the gas network needs to know if it is tampered with. The device features a switch which, when triggered, will send an immediate alert via LoRaWAN. 

Creating a proof of concept

The first technical breakthrough was verifying the most appropriate system design to meet the monitoring and reporting of pressure and under-pressure shut-off (UPSO) conditions. The initial focus was selecting and testing potential device components to build a proof of concept remote reporting, sensor and valve device. 

Due to the limited availability of electrical components at the time, we prioritised selecting and purchasing essential components early in the project and during the initial proof of concept phase. This approach ensured that critical stock was available for the prototype, minimising the risk of redesigning the circuit later.

How to test a hydrogen safety device

To test our proof of concept device, we conducted rigorous procedures, beginning with pressure testing to confirm gas-tight integrity. After assembling the testing rig with sensors and valves, we performed an initial operational test, installed electromechanical valves, and developed firmware to control valve operation based on pressure sensor data. Sensor readings were transmitted via LoRaWAN, prompting us to set up a server with a dashboard for data monitoring and analysis.

We then tested sensor accuracy, resolution, and stability across various pressures, comparing our selected sensors to a calibrated gauge to ensure reliability. Extended and repeated testing confirmed the durability and reliability of the chosen sensors, which demonstrated consistent performance across all pressure conditions. The testing results and sensor comparisons were documented in an end-of-phase report, allowing us to make a well-supported selection of the most suitable sensor for the device and to outline the rationale for this choice.

Following in-house testing, the device was sent to DNV in Groningen for external validation using hydrogen and methane to measure pressure response under varying humidity and temperatures, directly comparing results to those obtained with air in our test rig. 

Moving from proof of concept to prototype

After successful testing at DNV, we moved into prototype development, focusing on refining the device’s physical design and functionality. Confident that our proof of concept worked as intended, we prioritised de-risking the electronics supply chain by selecting and ordering essential components early.

Key steps included designing an optimised circuit with a LoRaWAN modem and antenna, a valve open/closed indicator, battery and power changeover with low-power operation for extended battery life, external power supply, and an electromagnetic compatibility (EMC) compliance review.

We reviewed and prototyped the printed circuit board (PCB) while designing and testing the physical product, including the casing, mounting, circuit board integration, and sensor fitting. This approach allowed us to assess the fit and function of each part and to make refinements before finalising the build. Initial power optimisation included remote battery level reporting to monitor and predict battery life.

Testing the initial prototype provided an opportunity to make design adjustments, ensuring the final batch of five devices met all performance and durability standards. This iterative process allowed us to incorporate improvements before full-scale manufacturing.

The conclusion of the development phase resulted in five fully functional prototypes that could be sent for external testing and deployment.

Extensive prototype testing

The prototype devices were shipped to DNV, where they underwent testing across various temperature ranges. Tests included closing and opening pressure functionality, valve leak testing, and steady-flow pressure drop measurements. Each test was conducted twice, once with methane and once with pure hydrogen. Following successful results, we could proceed with trials at NGN’s Low Thornley site.

Trials in a representative environment 

Five Smart Gas prototype devices are set to be trialled; three have already been installed and a further two will be fitted later this year. This will allow for extended testing on supply and future testing in a representative environment. At the moment, the Smart Gas device is at Technology Readiness Level (TRL) 6. Extended testing will provide feedback on the longevity of the devices and allow direct observation and feedback on the functions. It will provide information from the live gas supply to ensure reliable operation going into hydrogen trials. Successful completion of testing and trials will bring Smart Gas to TRL 7. 

Use case

The Smart Gas Pressure Sensor will fill the expected market need for monitoring supply pressure, whether it is for a blend of natural gas and hydrogen or 100% hydrogen. Where this measurement is required as part of the network’s hydrogen roll-out, the device ensures that the deployment will not face delays. The monitoring capabilities of the device and its automatic shut-off valve will also maximise the stability of hydrogen on the gas network. The device will provide near-real-time data retrieval at the point of supply so operators can view what’s happening anytime, anywhere. 

Network operators will be able to verify which end-user supplies are disconnected before restoring pressure, saving time and operational costs compared to manual reset procedures. Multiple engineer visits will no longer be required to both disconnect and reconnect the supply following an incident. The gas pressure monitoring at the point of supply will also show if there’s a problem, and shut-off valve monitoring will show if the supply is connected, without requiring an engineer to visit. 

From a customer perspective, reducing engineer visits will limit the disruption they face. Furthermore, the smart element of the device can be leveraged by operators to provide proactive notifications to customers if their supply has stopped and why. By offering timely messaging about a problem with the status of their supply, there is the possibility of increasing consumer confidence and acceptance of a new type of fuel. There is also potential to utilise data from the sensors to monitor the network. This will highlight pressure issues and allow the network to resolve them proactively, allowing fewer and shorter interruptions for the consumer.

Next steps

The Smart Gas device represents a significant step forward in energy innovation, offering flexibility and foresight in the transition toward a sustainable energy future. By holding the IP for the device, we’re positioned to explore and develop its capabilities further, ensuring it evolves alongside industry needs. Our participation in initiatives such as the Sustainable Ventures Hydrogen Innovation Challenge and the Digital Catapult Hydrogen Sensor Accelerator Programme has provided invaluable insights into the challenges and opportunities within the hydrogen sector, shaping our approach to future innovation. With compatibility across natural gas, 100% hydrogen, and blended supplies, the Smart Gas device remains a versatile and future-proof solution, ready to support the evolving energy landscape.

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