The Uniphos ASP-40 pump is a light weight and rugged piston and barrel type of air sampling pump that creates a vacuum in the pump barrel causing it to draw an accurate volume of sample air through the connected gas detector tube. The integrated end-of-stroke indicator changes colour to indicate the completion of sampling. The Uniphos ASP-40 pump is easy to operate and is designed for use with the entire Uniphos gas detector tube range.