- Author(s):
- Organization(s):
Applied Particle Principles, LLC
When testing dry powder inhalers (DPIs) for the size of particles discharged during each dose, manufacturers largely choose a test protocol that is recognized by the regulatory community and that walks a narrow pathway among device design, typical patient breathing characteristics and design principles of the cascade impactor that size-fractionates the discharged particles.
In this article, we a) show a method of testing inhaler flow control valves, b) show test data for the Parker valve 8FV12LN, c) explain the reasons for the confusing terminology (sonic, choked, critical) that typifies discussions of proper flow control and d) explain why the valve test method in the pharmacopeia is irrelevant to inhaler testing. Overall, the article emphasizes the need for testing and understanding flow control valves that are in routine use for setting the flow rate for DPI testing.
April 2026, Volume 20(2), pages 14-24