Flow Switches
for Reliable Flow and No-Flow Detection
Thermal flow switches for gas, liquid and slurry applications across industrial, biogas, process and energy systems.
Over 45 Years in Operation
1000's of UK Installations
Supporting 100's of UK Sites
Flow switches are used to detect the presence or absence of flow in gas, liquid and slurry applications.
By monitoring flow conditions and triggering alarms or shutdown signals when thresholds are reached, flow switches play a critical role in protecting equipment, maintaining safety and supporting reliable process operation.
Thermal flow switches are particularly well suited to industrial applications due to their no moving parts design, offering dependable performance across a wide range of process conditions including low flow, variable flow and challenging media.
Allison Engineering supplies a range of thermal flow switches covering general-purpose applications, ultra-low flow detection, analyser systems and configurable industrial duties, helping customers select the right solution for their process and site requirements.
Flow Switch Products
From cost-effective general-purpose switches to ultra-low flow and analyser-specific solutions, Allison Engineering can help specify the right flow switch based on your application, process conditions and installation requirements. Find a few examples of our range below.
FLT93B Flow Switch
A cost-effective, general-purpose flow switch designed for reliable liquid and gas flow detection.
Ideal for pump protection and fan failure applications, with robust construction and ex-stock availability.
FLT93L Flow Switch
A highly sensitive inline flow switch designed for ultra-low flow detection in liquid and gas applications.
Ideal for dosing systems and leak detection, with robust construction and configurable materials for demanding environments.
FLT93S / FLT93F Flow Switch
A robust thermal flow switch with sensor options for liquids, slurries and fast-response gas applications.
Configurable design with no moving parts, offering reliable switching performance in demanding industrial environments.
FS10A Analyser Flow Switch / Monitor
A compact, ultra-low flow switch designed for analyser systems and sampling applications.
Ideal alternative to rotameters, with LED indication, in-situ calibration and reliable performance for gas and liquid monitoring.
FS10i Flow Switch / Monitor
A programmable thermal flow switch and monitor designed for flexible installation and real-time flow indication.
Features configurable settings, LED flow display and live insertion capability for reliable monitoring across gas and liquid applications.
Why Choose Flow Switches
Reliable flow and no-flow detection
Detect changes in flow conditions to protect equipment, trigger alarms and support safe system operation.
No moving parts design
Thermal technology eliminates mechanical wear, helping reduce maintenance and improve long-term reliability.
Suitable for low and variable flow
Effective across a wide range of flow conditions, including ultra-low flow and fluctuating process environments..
Flexible monitoring options
Available as single-point, multi-channel and portable analysers depending on site requirements and operational needs.
Suitable for demanding environments
Designed for use in challenging biogas conditions, including wet gas, corrosive components and variable process conditions.
Supports efficiency and reporting
Reliable data enables better decision making, supports reporting requirements and helps improve long-term plant efficiency.
Suitable for Multiple Industry Sectors
Renewable Energy & Biogas
Designed for anaerobic digestion, biogas upgrading and renewable gas systems where accurate gas composition monitoring supports performance.
Power & CHP Systems
Supports gas quality monitoring for CHP units and combustion processes where consistency and efficiency are critical.
Wastewater & Water Treatment
Applicable to biogas and process gas monitoring across wastewater treatment sites where reliability and process insight are essential.
Landfill & Gas Recovery
Used for landfill gas monitoring and recovery systems where understanding gas composition is important for safety and performance.
Industrial & Process Applications
Suitable for gas analysis duties across wider industrial applications where monitoring supports control, safety and efficiency.
Energy from Waste
Used in waste-to-energy applications where gas analysis helps monitor combustion processes and maintain operational control.
Need information or advice?
Speak with our friendly, expert team to discuss your requirements and find out how we can help you.
Full Service UK Solutions
Allison Engineering supports biogas analyser projects from initial application review through to supply, commissioning and ongoing support. This ensures customers not only select the right analyser, but get reliable long-term performance.
Specifications & Planning
Application review, technical consultation, product selection and system planning based on gas composition, process conditions and monitoring requirements.
Supply & Commissioning
Product supply, installation and first fit support, commissioning and full setup to ensure analysers are working correctly in the field.
Support & Optimisation
Ongoing UK based servicing, calibration, maintenance and technical support to keep analysers accurate and systems performing reliably over time.
Biogas Analyser FAQs
Explore common questions about biogas analysers, including how they work, which gases are measured, where they are used and how to choose the right system for your application.
What is a biogas analyser?
A biogas analyser is a device used to measure the composition of gas within anaerobic digestion and renewable gas systems. It typically measures gases such as methane (CH₄), carbon dioxide (CO₂), oxygen (O₂), hydrogen sulphide (H₂S), hydrogen (H₂) and carbon monoxide (CO).
Biogas analysers are used to monitor process performance, support safety and provide reliable data for control and optimisation.
Why is biogas analysis important?
Biogas analysis is essential for understanding how an anaerobic digestion system is performing. By monitoring gas composition, operators can assess efficiency, identify issues and optimise the process.
It also plays a key role in safety by monitoring gases such as hydrogen sulphide and oxygen, and supports reporting requirements for compliance and performance monitoring.
What gases are measured in biogas systems?
Biogas analysers commonly measure methane (CH₄), carbon dioxide (CO₂), oxygen (O₂), hydrogen sulphide (H₂S), hydrogen (H₂) and carbon monoxide (CO).
The exact combination depends on the application, whether it is process monitoring, gas upgrading, safety or performance optimisation.
What types of biogas analysers are available?
Biogas analysers are available in several formats depending on the application:
- Single-point analysers for simple monitoring at one location
- Multi-channel analysers for monitoring multiple points across a process
- Portable analysers for on-site measurements, servicing and troubleshooting
The right choice depends on the level of monitoring required and how the system is operated.
Where are biogas analysers used?
Biogas analysers are used across a wide range of applications, including:
- anaerobic digestion plants
- biogas upgrading systems
- CHP units and combustion systems
- landfill gas monitoring
- wastewater treatment plants
- renewable energy and waste-to-energy facilities
They are used wherever understanding gas composition is important for control, safety and performance.
Are biogas analysers suitable for harsh environments?
Yes, biogas analysers are designed for use in challenging environments where gases may be wet, corrosive or variable in composition.
Industrial designs, protective enclosures and application-specific configurations ensure reliable operation in real-world conditions.
How do I choose the right biogas analyser?
Choosing the right analyser depends on:
- the gases to be measured
- number of measurement points
- process conditions
- installation location
- whether fixed or portable measurement is required
For example, a single-point analyser may suit simple monitoring, while multi-channel systems are better for larger or more complex plants.
The best approach is to review the application and match the analyser to the process requirements.
Why choose Allison Engineering for biogas analysers?
Allison Engineering has extensive experience supporting biogas and renewable gas applications across the UK, with a strong installed base and long-term customer relationships.
Our range includes single-point, multi-channel and portable analysers, allowing us to support everything from simple monitoring through to complex multi-point systems.
Combined with application knowledge, technical support and ongoing service capability, we help customers select and maintain the right solution for their site.
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Why Trust Allison Engineering
We are committed to delivering the highest standards across the specialist areas we support, combining proven products with practical engineering knowledge and dependable service.
Need Help Choosing the Right Biogas Analyser?
Allison Engineering can help you identify the right biogas analyser for your application, process requirements and site conditions.