Swagelok offers two categories of grab sample systems : Grab Sample Modules and Liquid-Only Sampling Systems.
The GSM uses pressure-rated sample cylinders which prevent the sample from escaping, even under pressure, and are durable to prevent accidental breakage. The GSM is the most reliable method of capturing a sample.
The GSM closed-looped sampling system pulls from a positive-pressure process and returns back to the process at a lower pressure location (e.g., upstream of a pump), using the differential pressure to drive the fluid through the sample system. This circuit draws a flow path that connects to the sampler then returns to the process or to flare.
A GSM can be left in the bypass or sample position indefinitely when using this arrangement, keeping the transport lines fresh (with zero flushing time) and ready for sample capture. A rupture disc is an available option for every GSM system. A relief valve can also be added to the sampling systems where there is additional concern regarding overpressure of the sample cylinder from temperature changes or overfilling.
A key feature of the GSM is the switching valve that directs flow. Using the Swagelok 40G series ball valve for this switching valve, configurations are available with either 2 or 3 valves.
The valves allow for simultaneous control of fluid routing, reducing the number of sequencing steps required to draw a sample.
The likelihood of errant sampling is reduced and a clear indication of sequencing is provided to the operator.
This valve assembly is standard on all GSM panels as well as fixed volume GSL panels.
A liquid-only sampling system (GSL) can be used in a number of liquid applications where the process fluid is not at risk of fractionating or evaporating when stored at atmospheric pressure. This allows the use of less expensive glass laboratory bottles to draw and store the sample. Using bottles also provides immediate feedback on the visual quality of the sample stream.
Swagelok GSL systems use the same switching valve as a GSM system to provide simplified operation for complex tasks.
The GSL systems also include Sentry Equipment’s Model MVS to draw a sample into a bottle. The MVS is equipped with a spring-return handle to prevent unintentional dispensing.
Swagelok GSL systems are designed around the use of Boston Round or media bottles but can accommodate other bottle geometries and materials.
GSL systems are assembled with Swagelok tube fittings, avoiding the potential leak points of NPT fittings.