Positioning of the Diffuser in the Foam Cylinder for ASTM D892 and D6082 Foam Test

The physical orientation of the diffuser will affect bubble size and therefore the results of the test. Thus, it is very important to be sure that the air-inlet tube is in the center of the cylinder and perfectly straight all the way down to the bottom. This is not an easy task. The Appendix of the method (Section 6.1 and Appendix X2.2.2) allows the use of a centering washer. Although this is currently not part of the main method, the ASTM Subcommittee is working on including this device in their next interlaboratory study.

Lawler Manufacturing offers several types of foam baths and varying levels of automation, including air foam, liquid bath, sequencer, and more. Learn more: http://www.lawlercorp.com/d892.html  and  http://www.lawlercorp.com/d892_liquid.html

Certification of the diffuser for ASTM D892 and D6082 Foam Testing

The diffusers used in foam testing must meet a certain permeability and pore diameter. The diffusers, especially the ceramic stones, change over time and fall out of specification, sometimes very quickly. They should be verified at least every week or every ten tests. The frequency necessary can only be determined by individual laboratory based on its experience for the types of samples analyzed.

Manual and Automated Diffuser Certification Apparatus are available from Lawler to save time and keep track of how the diffuser is changing. Lear more here: http://www.lawlercorp.com/d892_diffuse.html

Lawler has built an automated certification unit and dedicated it for re-certification of diffusers. For a small fee labs can send their diffusers to Lawler and get them back with results. Learn more about the service here: http://www.lawlercorp.com/d892_recert.html