Accurate gas analysis doesn't start at the analyzer. It starts at the process sampling point.
In continuous process gas analysis, selecting the right analyzer is only part of the measurement. Before an analyzer can provide a reliable result, a representative sample must be extracted from the process, transported without significantly changing its composition, and properly conditioned for analysis.
The complete measurement chain includes gas sampling, gas transport, gas conditioning, process control, and ultimately gas analysis.
Every step matters.
It Starts With the Sample
Gas sampling is the first step in the process.
Depending on the application, that sample may be coming from an environment with elevated temperatures or pressures, heavy dust loading, moisture, corrosive components, or other challenging conditions.
Those conditions influence how the sample should be extracted and which probes, sample tubes, filters, and materials should be used.
The objective is simple:
Get a representative sample out of the process and into the measurement system.
Getting the Sample to the Analyzer
Once extracted, the sample needs to travel from the process to the conditioning system and analyzer while maintaining its composition.
That isn't always easy.
Changes in temperature, condensation, deposits, chemical reactions, and other effects can potentially alter the sample during transport.
In applications where temperature is critical, heated sample lines can maintain the gas above its dew point and help prevent condensation before the sample reaches the conditioning system.
Pumps, tubing, fittings, valves, and sample lines all become part of maintaining a reliable sample from the process to the analyzer.
Conditioning the Sample
The gas coming directly from the process isn't always ready to be analyzed.
Sample conditioning prepares the gas for the analytical technology while helping protect the analyzer itself.
Depending on the application, conditioning can include:
- Gas cooling
- Condensate removal
- Filtration
- Gas conversion
- Dilution
- Washing or humidification
- Liquid protection
The goal is to provide the analyzer with a sample it can reliably measure while preventing moisture, particulates, liquids, or other process conditions from affecting the equipment or measurement.
Monitor the Entire Sampling Path
The condition of the sample also needs to be controlled throughout its journey.
Parameters such as temperature, flow, and the presence of liquids may need to be continuously monitored between the process sampling point and the analyzer.
Temperature controllers, liquid alarms, flow meters, and other monitoring technologies help ensure the sampling system continues operating within its intended conditions.
Think Beyond the Analyzer
The complete analytical measurement path can be thought of as:
PROCESS → SAMPLE → TRANSPORT → CONDITION → MONITOR → ANALYZE
A highly accurate analyzer cannot compensate for a sample that no longer represents what's actually happening in the process.
That's why sample handling shouldn't be viewed as an accessory to process analytics.
It's part of the measurement.
Engineered Around the Application
There is no universal sample conditioning system.
The right solution depends on the process and the measurement being made, including:
- Temperature and pressure
- Dust and particulate loading
- Moisture and dew point
- Corrosive components
- Sample composition
- Required measurement
- Analyzer technology
- Distance to the analyzer
- Installation environment
Understanding these conditions allows the complete sampling and conditioning system to be designed around the actual application.
Better Samples Mean Better Measurements
Process Analytics is ultimately about producing information operators can trust.
That reliability starts well before a measurement appears on a screen.
From extracting the sample at the process to transporting, conditioning, and monitoring it on the way to the analyzer, every step contributes to the accuracy and reliability of the final measurement.
TechStar's Process Analytics approach considers the complete measurement system, helping ensure the technology surrounding the analyzer supports the measurement itself.
Because before you can trust the analyzer, you have to trust the sample.
