Preproduction plastic, commonly known as plastic pellets – and also called nurdles – is comprised of raw plastic resin materials that are heated and reformed into a wide variety of plastic products.

Plastic pellets can range in diameter size from 1 to 5 mm., making them ideal for common molding processes, including:

• Extrusion – plastic wraps and sheets
• Blow molding – plastic bottles
• Injection molding – containers and tubs
• Rotational molding – toys, furniture, garbage cans and other large items

 
On average, about 250 billion pounds of nurdles are manufactured and shipped worldwide every year.

Held back by a disruptive sampling process

A polyethylene plastic pellets manufacturer in east Texas had been taking hand samples of product from a valve located in the side of the transport line. Personnel would take a sample manually three times per batch of product for quality control purposes, with the first sample needed to continue running the process. This method was labor- and time-intensive and was not yielding a representative sample, as sample was gathered from the inside edge of the pipe only.

Improving production efficiency and quality

The plastics operation chose to implement two Sentry PR Automatic Point Samplers, which take a sample of free-flowing materials from pneumatic conveying lines. In this application, the customer chose to obtain samples of finished product before it was conveyed to either packaging or truck and rail loading. The samplers were mounted in the conveying lines right before they exited the building to loadout. This new method of sampling plastic pellets using the PR sampler allowed the facility to automatically gather a point sample of the product with each sampling instance.

Sample automation was controlled by the Sentry P2B-4/7 sampler controller. Using the sampler controller, the operator can gather the first required sample by pressing the “hand” option as many times as required to collect the needed sample volume. The operator then changes the container and places the sampler controller in “auto” and utilizes the “batch” option. This allows the sampler to collect pellets samples automatically at a rate set on the timers located inside the enclosure.

By utilizing the batch option on the sampler controller, the facility was able to continuously collect composite samples representative of the process over the course of the elapsed time. Using the sampler controller batch option reduced waste as well as the possibility of over-filling the sample container, which could result in wasted product or a potential spill.

By implementing a Sentry automatic sampling solution within its process, this plastics manufacturer improved efficiency and gained confidence that their sample analysis results were based on truly representative product samples.

Learn more about our chemical and petrochemical product samplers.