One common petrochemical process is the creation of preproduction plastic pellets, which are raw plastic that is heated and reformed into a wide variety of plastic products. Plastic pellets can range in size from 1 to 5 mm, and they can end up as wraps, sheets, bottles, containers, tubs, furniture, garbage cans or other items of all shapes and sizes.

To most effectively take a representative sample of plastic pellets for analysis that ensures product quality and consistency, it is best to automate sampling within the production process. While some manufacturers still take hand samples of product, this can be labor- and time-consuming, and the hand-sampling method may not yield a representative sample.

Manual hand samples of product are labor- and time-consuming,
and may not yield a representative sample.

Many plastics manufacturers are realizing their sample quality is compromised and are implementing automated sampling solutions. For instance, one southwestern U.S. chemical processor wanted to obtain a sample of polyethylene pellets from a loadout system designed to automatically archive composite samples of the pellets into a sample bag. However, the current sampling solution did not have the ability to automate and archive the samples.

Plastic pellets sampling, automated and customized  

The petrochemical company searched for a new sampling solution that could sample free-flowing materials such as pellets from screw or drag conveyors or sloped gravity chutes. A sampler like the Sentry® A automatic point sampler captures samples from a point in a process stream and often is used when the material is homogenous. To obtain a sample, the sampler’s air cylinder opens a sliding gate on the sampler, and the product sampled is discharged through a flexible hose to a collection point. Product characteristics are not affected by the sampler because no moving parts convey the product to the sample container.

In this case, the Sentry A sampler was modified to serve as a diverter to allow two sample bags to collect the pellets. A Sentry SBC sampler controller was used to control the sampler as well as the diverter; sample volume and frequency can be changed at the sampler controller.

This plastic pellets sampling solution allowed the facility to automatically gather a representative point sample of the product with each sampling instance. With the sampler modification, facility management could meet its goal of automating and archiving pellets samples into sample bags.

Representatives from the original sampling provider, based in Germany, conducted a final inspection visit at Sentry Equipment Corp along with a third-party inspection representative, and noted that they were “blown-away” by the top-notch quality of Sentry products, manufacturing facility and people.