Gr Sprenger Engineering Case Histories

Case History:
Pesticide Formulation and Packaging

Unreliable Sample Quality Causing Rework

An agricultural pesticide manufacturer operates a formulation and packaging facility which produces 105,000 pounds per shift of dry granular insecticide. The finished product is packaged in 50 pound heat-sealed bags which are palletized for shipment immediately following the end of the bagging line. Analysis of samples, collected by a conventional automatic auger tube sampler, installed in the bagging unit feed hopper, showed variations in active ingredient concentrations in excess of allowable limits. Adjustments to sampling frequency and auger tube configuration had no beneficial effect. The facility resorted to sampling each pallet of finished product by hand. The analysis results showed that the grab samples collected by hand were much more dependable (fewer and smaller variations) than the auto-sampler. Product from the opened bags had to be reprocessed through the packaging line and opened bags had to be thrown away. Extra costs for labor and waste were generated by repackaging product and disposal of damaged bags.

A Sprenger Continuous Solids Sampler was installed in the product stream just prior to the bagging unit feed hopper. Analysis of the samples from the new continuous sampler matched the grab sample analysis. Manual grab sampling and the attendant bag waste and reprocessing costs were eliminated. Laboratory handling of the collected samples (approximately 6 lb./hr) was much easier and less wasteful due to the reduced sample volume. This Sampler was installed in 1978 and continued operating until the packaging line was reconfigured in 1994.