Chemical Injection Flow Monitoring Using Thermal Flow Switches

Why Chemical Injection Monitoring Matters

Chemical injection plays a critical role in maintaining oil and gas production systems.

Corrosion inhibitors, scale inhibitors and methanol are routinely injected into wells and pipelines to:

• Prevent corrosion and infrastructure damage
• Inhibit scale formation and blockages
• Maintain flow efficiency and production rates
• Protect downstream processing equipment

However, these systems operate under extreme pressures and very low flow rates, making accurate monitoring essential.

Without reliable flow detection, operators risk undetected chemical loss, equipment damage and costly production issues.

The Problem: High Pressure, Ultra-Low Flow

Chemical injection systems present one of the most demanding flow monitoring challenges in industry.

Typical conditions include:

• Operating pressures of 300–400 Bar, often higher
• Extremely low flow rates, sometimes below 1 litre per hour
• Pulsating flow from injection pumps
• Aggressive and corrosive chemicals
• Critical requirement for continuous and accurate dosing

Many traditional flow measurement technologies struggle under these conditions.

The result can be:

• Undetected loss of injection
• Over or under dosing of chemicals
• Increased risk of corrosion or scaling
• Reduced system efficiency and reliability

The Solution: Reliable Low Flow Detection

In chemical injection systems, the priority is often not full flow measurement — but reliable confirmation that flow is present.

Flow switches provide a robust and effective solution by:

• Detecting loss of flow immediately
• Monitoring low-flow conditions in real time
• Providing alarm or shutdown signals to protect the system
• Operating reliably under extreme pressure conditions

This ensures that chemical injection remains consistent and effective.

Why Thermal Flow Switches Are Effective

Thermal flow switches are particularly well suited to chemical injection applications due to their ability to detect very low flow rates under challenging conditions.

Key advantages include:

• Reliable low-flow detection down to extremely small flow rates
• No moving parts, reducing maintenance and failure risk
• Strong resistance to pressure, vibration and pulsation
• Suitable for aggressive and corrosive fluids
• Stable performance in high-pressure environments

This makes them a preferred solution where other technologies may be impractical or unreliable.

Recommended Products for Chemical Injection Monitoring

The FLT93L thermal flow switch is specifically designed for ultra-low flow detection in high-pressure systems, making it ideal for chemical injection applications.

It is widely used across the oil and gas industry to monitor injection pumps and ensure consistent chemical dosing.

The FLT93L is capable of operating at pressures up to 700–800 Bar, while detecting flow rates as low as 0.15 litres per hour — a critical requirement for many injection systems.

Its fully welded inline sensor design provides a robust and reliable solution for demanding process conditions.

Key Features:

• SIL2 rated for safety-critical applications
• ATEX Exd certified for hazardous areas
• Operating pressures up to 800 Bar
• Ultra-low flow detection down to 0.15 litres per hour
• Flanged or clamp hub process connections
• Available in corrosion-resistant materials

These capabilities make the FLT93L particularly effective for monitoring corrosion inhibitor, scale inhibitor and methanol injection systems.

Typical Chemical Injection Applications

Chemical injection flow monitoring is used across a wide range of oil and gas processes:

• Corrosion inhibitor injection systems
• Scale inhibitor dosing systems
• Methanol injection for hydrate prevention
• Subsea and topside injection systems
• Wellhead and pipeline chemical dosing
• Enhanced oil recovery processes

In all cases, maintaining correct injection rates is critical to asset protection and operational efficiency.

Installation & Application Considerations

Correct selection and installation are essential for reliable performance.

Key factors include:

• High-pressure rating and process connection requirements
• Compatibility with injected chemical composition
• Flow range and detection sensitivity
• Installation within injection lines or pump discharge
• Hazardous area classification (ATEX / SIL)

Inline sensor designs are typically preferred to ensure accurate and stable detection at very low flow rates.

Our Experience & Approach

At Allison Engineering, we have extensive experience supporting chemical injection systems across oil and gas applications.

We understand that:

The challenge is not just measuring flow - but ensuring reliable detection under extreme conditions.

Our approach focuses on:

• Understanding the injection system and operating conditions
• Selecting proven technologies suited to high-pressure, low-flow applications
• Supporting correct installation and configuration
• Providing ongoing technical support and expertise

This ensures dependable performance and long-term protection of critical assets.

See also:

Pump Protection Using Flow Monitoring and Flow Switches

Analyser Sample Flow Monitoring Using Flow Switches

 

Key Benefits

• Accurate detection of extremely low chemical injection flow rates
• Reliable operation at very high pressures in demanding environments
• Prevents under-injection that can lead to corrosion, scaling or process failure
• Helps optimise chemical usage and reduce unnecessary chemical costs
• Early warning of pump or injection system failure
• Robust, no-moving-parts design for long-term reliability and low maintenance