Analyser Sample Flow Monitoring Using Flow Switches

Why Analyser Sample Flow Monitoring Matters

Process analysers rely on a continuous and representative sample flow to deliver accurate and meaningful data.

These systems are used to monitor:

• Gas composition
• Product quality
• Process efficiency
• Environmental emissions
• Thermoconductivity and other key parameters

If sample flow is lost, reduced or interrupted, the analyser can no longer provide valid data, often without immediate visibility.

This can lead to incorrect readings, process inefficiencies and potential compliance risks.

The Problem: Loss of Sample Flow

Sample systems are typically small-bore, low-flow and sensitive to process conditions.

Common issues include:

• Blockages in sample lines
• Condensation or contamination
• Pump or pressure issues
• Valve or system faults
• Gradual flow reduction over time

Historically, rotameters have been used to indicate flow.

However, they present several limitations:

• Visual indication only - no alarm or signal output
• Moving parts prone to sticking or failure
• Poor performance at very low flow rates
• Limited suitability for high temperature applications
• No integration with control or safety systems

In many cases, rotameters become a point of failure rather than a reliable solution.

The Solution: Flow Switch Monitoring

Flow switches provide a simple and effective way to monitor analyser sample flow continuously.

They enable operators to:

• Detect loss of flow immediately
• Monitor low-flow conditions that indicate developing issues
• Trigger alarms or shutdown signals
• Integrate with control and safety systems

This ensures that sample flow is always present, and that any issues are identified early.

Why Thermal Flow Switches Are Effective

Thermal flow switches are particularly well suited to analyser applications due to their ability to detect very low flow rates reliably.

Key advantages include:

• Accurate detection of ultra-low flow conditions
• No moving parts, eliminating mechanical failure risk
• Reliable operation across gas and liquid sample streams
• Strong performance at elevated temperatures
• Stable and repeatable detection even in variable conditions

This makes them a significant improvement over traditional rotameter-based systems.

Recommended Products for Analyser Sample Flow Monitoring

The FS10A analyser slow switch is specifically designed for use in process analyser systems.

It provides reliable detection of sample flow in both gas and liquid applications, ensuring analysers receive a consistent and valid sample.

The FS10A is designed to integrate directly into analyser systems, including installation within standard tee pieces or modular manifolds such as SP76 (NeSSI) systems.

Key Features:

• Designed specifically for analyser sample flow applications
• SIL2 rated for safety-critical monitoring
• ATEX Zone 1 & 2 certified
• Ultra-low flow detection (gas from ~10 cc/min, liquid from ~0.7 cc/min)
• Operating temperatures up to +260°C
• 4–20 mA output and relay alarms for system integration
• 10-segment LED display for local flow indication
• In-situ calibration and adjustment via push-button interface
• Available in 316 stainless steel or Hastelloy

The FS10A provides a robust and reliable alternative to rotameters, delivering both local indication and system-level monitoring.

Typical Analyser Sample Flow Applications

Analyser flow monitoring is used across a wide range of industries and systems:

• Gas analysers in oil and gas processing
• Emissions monitoring systems
• Chemical process analysers
• Biogas and renewable energy systems
• Laboratory and process sampling systems
• Thermoconductivity and composition analysis systems

In all cases, maintaining consistent sample flow is essential for accurate and reliable measurement.

See also:

Pump Protection Using Flow Monitoring and Flow Switches

Chemical Injection Flow Monitoring Using Thermal Flow Switches

Analyser Shelter Air Flow Monitoring

 

Installation & Application Considerations

Correct installation ensures accurate and dependable flow detection.

Key considerations include:

• Integration into sample lines or analyser panels
• Compatibility with existing manifold or tubing systems
• Flow range and sensitivity requirements
• Operating temperature and pressure conditions
• Hazardous area classification

Compact designs and flexible mounting options make these devices well suited to analyser systems.

Our Experience & Approach

At Allison Engineering, we have extensive experience supporting analyser systems across multiple industries.

We understand that:

Accurate analysis depends entirely on reliable sample flow.

Our approach focuses on:

• Identifying risks within the sampling system
• Replacing unreliable or outdated technologies such as rotameters
• Implementing robust, low-maintenance solutions
• Supporting long-term system reliability and performance

This ensures analysers operate with confidence and deliver meaningful data.

Key Benefits

• Reliable confirmation of sample flow to critical analysers
• Early detection of blockages, leaks or flow loss
• Improves accuracy and reliability of analytical measurements
• Reduces reliance on fragile rotameters and manual checks
• Suitable for very low flow rates in gas and liquid sampling systems
• Compact, low maintenance design with no moving parts