Key Sensors for Wet & Dry Scrubber Emissions Monitoring

Brian Craig

July 18, 2025

In today’s increasingly regulated industrial landscape, emission control systems like wet and dry scrubbers play a vital role in reducing pollutants from flue gases. But efficient scrubbing is only part of the equation, accurate, reliable sensor instrumentation is what ensures these systems operate within compliance, stay optimized and avoid costly downtime.

Whether you’re upgrading a scrubber system in a chemical plant or troubleshooting one in a power generation facility, selecting the right sensors is critical. At The Transmitter Shop, we help operators across industries make informed instrumentation choices that support both performance and compliance.

In this blog, we’ll break down the key sensors used in wet and dry scrubber systems, their role in monitoring emissions and how smart sensor technology can improve system reliability and efficiency.

Hydrogen Gas Safety

Why Emission Monitoring Matters in Scrubber Systems

Wet and dry scrubbers are designed to remove harmful gases (like SO₂, NOx, and HCl) and particulates from industrial exhaust. To ensure effective pollutant removal and maintain regulatory compliance (EPA, state agencies, etc.), operators must continuously monitor process variables such as:

pH levels (for chemical reactions)
Liquid or gas flow rates
Differential and static pressure
Fluid levels
Gas temperature

Without the right instrumentation, even the best-designed scrubber system can underperform, leading to environmental violations, safety risks and unnecessary operational costs.

Key Sensors for Wet Scrubber Systems

Wet scrubbers use a liquid-based scrubbing media to absorb and neutralize pollutants. Monitoring here focuses on maintaining the correct chemical balance, flow rates and system pressure.

pH Sensors: pH sensors monitor the acidity or alkalinity of the scrubbing liquid, which is critical in neutralizing acid gases like SO₂. A stable pH helps maximize absorption efficiency and minimize reagent waste.

Pro Tip: Choose pH sensors built for high humidity and corrosive environments and ensure they’re easy to calibrate or replace during maintenance.

Flow Transmitters: These sensors help maintain liquid circulation rates through spray nozzles or towers. Too little flow reduces cleaning efficiency; too much can cause overflow or pump strain.

Differential Pressure Transmitters: By tracking pressure drop across scrubber sections, these transmitters help detect early signs of clogging, buildup, or fan malfunction. Real-time pressure monitoring is crucial for safety and reliability.

Level Sensors: Used in sumps or recirculation tanks to prevent overflow or dry running of pumps. Reliable level measurement helps maintain operational consistency and prevent downtime.

Key Sensors for Dry Scrubber Systems

Dry scrubbers typically use solid sorbents or slurries to absorb pollutants without the use of liquid scrubbing media. They require precise monitoring of flow, pressure, and gas temperature.

Differential Pressure Sensors: Critical for tracking the condition of filters or absorber beds, these sensors alert you when systems are experiencing resistance from dust accumulation or blockages.

Gas Flow Sensors: Gas flow meters ensure consistent flue gas velocity, which is essential for effective reagent injection and pollutant contact time.

Temperature Sensors: Gas temperature directly affects reaction efficiency and sorbent behavior. Temperature sensors help maintain ideal process conditions and identify combustion or fan issues early.

Smart Sensor Technology: A Modern Advantage

Today’s leading-edge scrubber systems increasingly rely on smart transmitters with features like:

Digital communication protocols (HART, Modbus)
Self-diagnostics and alert capabilities
Remote configuration and monitoring

These smart instruments not only reduce maintenance burden but also integrate seamlessly with PLC/SCADA systems for real-time data analysis and compliance reporting.

At The Transmitter Shop, we offer a wide range of smart and legacy transmitters from trusted names like Rosemount, Vega, Bourdon, Otis Instruments, Foxboro and PR Electronics, all available in new surplus or reconditioned.

Choosing the Right Sensor for Your Scrubber System

When selecting sensors for scrubber applications, consider:

Environmental conditions: Corrosive gases, high humidity, or particulate-laden flows require rugged, chemically resistant sensors.
Sensor compatibility: Ensure your new sensors integrate easily with your existing control system.
Maintenance needs: Consider accessibility and calibration frequency.
Budget constraints: Reconditioned or surplus sensors can offer exceptional performance at reduced cost.

Need expert help? Our team has over 30 years of hands-on experience in process instrumentation and can help you size, select, and source the right solution, fast.

Why Choose The Transmitter Shop?

At The Transmitter Shop, we do more than sell transmitters, sensors we provide trusted instrumentation solutions for process-critical systems, including scrubbers used in:

Chemical & petrochemical plants
Power generation facilities
Pulp & paper mills
Waste incinerators
Food & beverage processing

With one of the largest ready-to-ship inventories in the U.S., we offer, new surplus & reconditioned sensors, 2-year warranty on most products and Personalized support and sizing assistance

If you're upgrading a scrubber system or troubleshooting emission issues, having the right sensors makes all the difference. Contact The Transmitter Shop today to get matched with dependable, cost-effective transmitters that meet your specific scrubber system requirements.

Browse our inventory or get a quote today at www.transmittershop.com