Operational Best Practices for Swagelok’s Grab Sample Stations

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Interested in seeing how the grab sample module works? This module is availabe for viewing through our Custom Solutions department - get in touch with us to see it in person or download the PDF for more information.

We've written before about the advantages of a Grab Sample Station from Edmonton Valve & Fitting. It's a great way to get samples at the right conditions for analysis, and be able to assess it quickly.

A Grab Sample will have all the features mounted on a single panel, including our geared valve assembly for safe sampling, quick connect couplings for repeatable connections, hose for flexible connection to the sample cylinder, a pressure gauge for identification of pressure release, and a cylinder support.

Leave some space

Regardless of the type of container used for manual sampling of petroleum and petroleum products, the sample container should be large enough to contain the required sample volume without exceeding 80 percent of the container capacity. For a sampling of liquefied petroleum gases, for example, purge the container and fill it with liquid, then vent liquid so that 80 percent or less of the liquid volume remains.

To avoid contamination, don't mix old and new streams. And never sample a liquid close to its flashing point or boiling point. Transport and sample a gas above its dew point. The faster you analyze the sample the better. Aim for one minute or less.

Sequences

For manual gas sampling, first connect the sample cylinder to the Grab Sample Station with quick connects. Next, connect the hose to the sample cylinder with quick connects. In Sample mode, the system pressure will increase. You capture the sample by closing the cylinder valves. Then vent off the system pressure and disconnect the sample cylinder. Close the loop by connecting the hose stem into the quick connect body.

For volatile liquid sampling, you need a low flow to fill up the cylinder. Be aware that low flow pressure can vapourize the light components, changing the composition of the sample.

Remember, we make the Grab Sample Stations right here in Edmonton to your order. We can add a purge option, and we have a couple of different pressure relief options too. We'll be glad to talk with you about your specific needs and help you make the right choices. To help get you started, download the Grab Sample Module PDF here.