In the past we have had some customers asking us how important the Hartmann chamber is in determining Class 2 ignition for Kst and Pmax. We use a modified Hartman as a tool to aid us in the explosibility screening test, otherwise known as the Go/No Go.
The ASTM E27.05 subcommittee withdrew the 1.2-L Hartmann tube in 2007 as an acceptable vessel for Pmax and Kst determination by withdrawing ASTM E789 (https://www.astm.org/Standards/E789.htm).
The 20 L volume is the lowest volume that can be used for quantitative testing and have results that are, on average, similar to the 1-m³ chamber – which is the “Gold Standard" for generating deflagration values for explosion protection.
We do however use an open glass system Modified Hartmann Tube for qualitative assessments of deflagrability so as to act as a prescreening for 20-L or 1-m³ chamber Go/No Go screening tests per ASTM E1226 Section 13. Additionally, not just any 20-L test chamber can be used in ASTM E1226. The chamber has to be calibrated to produce the appropriate Pmax and KSt for reference dusts.
If you have any questions or need guidance on combustible dust testing or how to reduce risk when handling these materials, please contact us at firstname.lastname@example.org We look forward to being a resource to you.