History of the test method
IEC and EN 61331-1 and 61331-3 were revised in 2014. The test method standard, EN 61331-1:2014, lists a number of test methods, including Narrow Beam, Broad Beam, and Inverse Broad Beam tests. The product standard, EN 61331-3:2014, specifies the Inverse Broad Beam method (known as IBG) for testing of protective aprons and other devices. The IBG method was a significant improvement over the original test method, as secondary radiation and fluorescence emissions are measured, and a range of X-ray energies tested.
In 2015, some Notified Bodies expressed concern with testing techniques being used by laboratories. Ludwig Büermann of PTB (Physikalisch-Technische Bundesanstalt, Germany’s national metrology institute), the Chair of the IEC working group for the 61331 standards, published a detailed methodology for the test method in 2016. This is known as Inverse Broad Beam with Guidance Note (IBG*).
The Co-ordination of PPE Notified Bodies Vertical Group 5 – Protective clothing and gloves (VG5) approved a Recommendation for Use (RfU) in 2017, which recommended the use of the IBG* method.
Practical experience with the IBG* method showed that it was lengthy, costly, and did not show any significant improvement for test results. Dr Heinrich Eder of the Bavarian State Office of Weights and Measures (LMG), conducted a three-lab trial, and found no benefit from the IBG* method.
Dr Eder then published a paper in late 2017 which suggested a modified Broad Beam method, known as BBG*. An interlaboratory trial using this method was conducted in 2018 with four laboratories, which showed good agreement. The BBG* method is said to be simpler, cheaper, and more testable by end-users, and has broad support from suppliers and laboratories.
In May 2019, VG5 agreed a new RfU, which recommends the use of the BBG* method. This was finalised and sent to NotifiedBodies in July 2019. This RfU has to go through an approval process with the PPE Expert’s Working Group (the EuropeanCommission and the EU member states) before it is published on the EU’s website, however Notified Bodies can apply this RfUnow.