Sampling Basics
Grab sampling, also known as lab sampling or spot sampling, is the collecting of a sample of liquid or gas in a pipeline, tank, or system with the intent of transporting the sample to a laboratory for analysis.
Why use a Grab Sample System?
Grab sampling can validate:- Process conditions
- End products meet quality specifications
- Online analyzers are "fit for use"
- Product quality during custody transfer
It can also provide verification of environmental emissions. In all of these uses, capturing a representative sample is essential. However, placing a captured sample into an open bottle for transport back to the lab may not provide a representative sample. Some chemicals will evaporate or fractionate if not maintained under pressure.
Sampling is the science of safely capturing a sample from a process or a pipeline while maintaining the chemical composition during storage or transport for later analysis. Depending on the process phase, temperature, consistency, chemical makeup and other factors, there are a variety of approaches that can be used to extract a sample. Determining the container type needed is the first decision that must be made in order to select the appropriate sampler. If you're interested in a quick look at our Grab Sampling Systems, click here.
Another important aspect is the temperature of the system fluid. Many processes operate at elevated temperatures and can pose a hazard from direct scalding during operator interaction or from the temperature limits of seats and seals being exceeded. Swagelok recommends consideration of a sample cooler when the supply temperature exceeds 140°F (60°C). Note that thermal safety may affect sample integrity.