PTQ Q4 2023 Issue

Another advantage bottles have is that they are a low - er-cost collection option and can be replaced easily as the need arises. In addition, used bottles are easy to discard. Typically, tapered bottle shrouds keep the septum and nee - dle aligned with the grab sampling system, which prevents accidental spillage and broken needles. • Cylinders: It is recommended that cylinders be chosen when a gas or liquid must be captured under pressure from the sampling system (see Figure 3 ). Unlike bottles, cylinders keep the sample under pressure during transport which can prevent evaporation or fractionation of the chemicals. Most sample cylinder containers are constructed using seamless tubing to ensure consistent wall thickness, size, and capacity. Internal neck smoothness prevents fluids from being trapped, enabling easy cleaning in the lab so cylinders can be reused. Specifying a grab sampling system For the lab analysis to be valid and useful, you must ensure your sample remains representative of the fluid within your system. In addition to maintaining the phase of a captured sample, there are several characteristics to keep in mind prior to choosing an analytical grab sampling system. Given the wide variety of configurations available, consider the following criteria: • Pressure: Whether you are using a grab sample mod - ule or a liquid-only sampling module, the system’s maxi - mum-rated pressure must not be exceeded • Temperature: Each sampling module system has a maxi - mum, and sometimes minimum, fluid operating temperature • Hazardous material: The grab sampling system selected must protect the operator and the environment alike from the system fluid. Certain chemicals require strict leak or chemical protection • Materials of construction: The materials used in your chosen closed-loop system must also be compatible with the system fluid • Surface treatments: Surface treatments can reduce the absorption and adsorption of the sample fluid into metallic surfaces, leading to a more representative sample • Purge: Some chemicals may leave residue or contami - nants if not flushed from the system. Selecting a purge option provides a means to introduce a purge fluid to remove contaminants from sample lines. Systems can also be customised to make them even safer. For example, by producing a closed-loop sampling system for specific plant applications. Quality considerations A properly designed and constructed closed-loop system can keep leaks at sampling points to a minimum. When deciding which closed-loop system to build, it is critical to consider the following features: • Constructed from leak-tight components • Designed and assembled to minimise potential leak points • Sample drawing technology • Reducing emissions at sampling points. The quality of a sampling system is dependent on how well its components are manufactured. For example,

Figure 3 Cylinders are commonly used in grab sampling for collecting gases or liquids under pressure

flows back to the main process without exposing the oper - ator or atmosphere to the fluid in question. In contrast, some sampling methods may involve drawing process fluid, flowing it through a sampling point, and then eliminating the excess through flaring or another disposal process. Others may tap directly into the main process sys - tem and have operators draw fluid manually into open con - tainers. The drawback to these methods is that they expose operators to the process fluids or expose the atmosphere through flaring or other disposal processes. A properly designed and constructed closed-loop system can keep leaks at sampling points to a minimum Closed-loop systems cut down on waste by returning fluid to the main process and preventing unnecessary expo - sure to the fluid. They are often the most effective solution to reduce fugitive emissions and keep your operators safe. Choosing the right container Collecting the sample itself is important, but it is even more critical to ensure the captured sample stays representative while it is being transported to the laboratory. Using an open bottle for transport, for example, may result in con - tamination and lead to evaporation or fractionation if proper pressure is not maintained. Typically, two different kinds of containers will be used depending on the type of system involved: • Bottles: Bottles are often the most appropriate container to simplify sample collection and transportation. It is often recommended that bottles be used for liquids that do not require pressurisation because they can be drawn and transported without evaporation or spillage risks. To ensure tight seals, use a bottle with a self-sealing septum cap.

PTQ Q4 2023