The N.P.T. Purging compound is a chemically cleaning purging compound that uses no physical scrubbing and does not need any soak time to thoroughly clean the barrel and screw. The effective temperature range of the purging compound is 160-600. All it take is 1 1/2 times the barrel capacity to purge the barrel and you can go directly into running your plastic after the purging process. N.P.T is a non hazardous and FDA compliant. Do not use this product with Acetal or Delrin.