Sampling can be used to identify process variations and for process control, environmental monitoring, product quality assurance and custody transfer. Following proper steps reduces sample to sample variation. Characteristics of one representative sample are the same of that of the entire lot or batch – and the sampling methods and results should be consistent, accurate and repeatable.
Why sample?
For sampling of solid and powder materials, the sampler must be suitable for the material being sampled and must be able to fit and operate in its designated area and environment. The specific sampler model chosen and/or designed for a customer depends on the application it will be used for and the environment it will be used in. Bulk solids typically are sampled from hoppers or drop chutes; pressure or vacuum conveyor lines; air slides and moving conveyor belts.
Point style samplers sample from a point in the material stream. They most often are used when conducting chemical analysis or when the material is homogenous. Strip style samplerstake a sample from a strip across the diameter of a material stream, and are used in situations where product segregation exists. Crosscut style samplers take a cross section of an entire product stream. They can provide the most representative sample, but require a lot of headroom above them to operate.
The following customer application stories illustrate how different applications require different sampler configurations, and often custom modification.
Two chemical processing customer stories
1) A chemical processing customer had the need to take samples of fly ash, a chemical waste product, from four pneumatic conveyor line locations with down to up vertical flow. Fly ash is free flowing, dry and abrasive, so stainless steel containers were needed.
The Sentry® PR automatic point sampler was the best solution for this application, as the sampler can handle the pressure of the pneumatic conveyor line as well as the abrasive powder, and can be mounted vertically. An outer nose style line adapter was provided to assist in providing quick delivery.
2) Another chemical processing customer needed to sample catalyst material coming off a dryer discharge. Because catalyst material has a cylindrical shape and can be up to a half-inch in diameter, an oversized sampler would be required. However, the available headroom for a sampler, from the dryer discharge to the inlet of a bucket elevator, was less than four feet vertically.
The best solution for this application was an oversized Sentry RX automatic strip sampler with a three-inch diameter sample tube. Our engineers designed a custom premount section with square flanged ends for the customer’s four-inch square angled chute.
Two minerals processing customer stories
3) A minerals processing customer needed to take samples of pentahydrate borax from a hopper just upstream of its loadout area. A strip sample was required, but the vertical height from the area where samples were to be taken was very limited for the design – approximately 12 inches. The installation point was a trapezoid-shaped chute, and sample needed to be delivered to the loadout area on the floor below.
The Sentry D2 automatic strip sampler was best suited to the application. Our design engineers created a special mounting adapter arrangement for the customer’s trapezoidal chute, and supplied flex hose at the discharge that was routed through a hole cut in the floor to a collection container located at the loadout level one floor below.
4) Another minerals processing customer needed to sample one gallon each of free-flowing, free-falling materials from 10 locations. The process lines were at angles, with varying height clearances. The sample temperatures ranged from 100°F to 250°F, so a mix of bag adapters and stainless steel containers were needed for sample collection.
The customer needed all three different types of samplers to meet its application needs. The best solutions for this customer were the Sentry RX automatic strip sampler for eight locations, Sentry RPG automatic point sampler for one location, and Sentry SA automatic crosscut sampler for the last location. The RPG sampler was selected due to vertical clearance restrictions, while the SA was needed at the loadout station. Our design engineers designed pipe wraps to accommodate different chute angles and the vertical clearance needed for each sampler, with different line adapters for each chute angle. Finally, high temperature seals were used for the RX samplers.
These customer application stories illustrate that our design engineers are ready to tackle any application, anywhere.
Learn more about our solid & powder sampling solutions here.
This article was originally published on our website.
