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

Kinematic Viscosity Testing Advice for ASTM D445 KV Test

The entire length of the viscometer must be maintained at the appropriate temperature. The type of circulator used, the age of the bath fluid, and the bath fluid viscosity will impact temperature uniformity. The circulator and the viscosity of the KV bath fluid need to be balanced to provide a uniform temperature throughout the bath. Change the bath fluid as soon as it begins to discolor, as discoloration usually indicates the fluid has oxidized and the viscosity has increased. The KV bath should not be located near a draft or in a fume hood, which can cause excessive temperature gradients in the bath.

Lawler Model 86-20 http://www.lawlercorp.com/d445_high.html  for high temperatures and the Model 70 Series (74, 77, 78, 79) http://www.lawlercorp.com/D445_1_UK.htm kinematic viscosity baths are designed with strong bath agitation and in enclosed cabinets to reduce the effect of room drafts.

Temperature stability is critical for ASTM D445 Kinematic Viscosity

Temperature control is the single most important parameter for obtaining accurate and precise kinematic viscosity measurements. For petroleum products even more so, as their rate of viscosity change per unit of temperature is significantly greater than other types of materials. Thus, a slight variation in temperature can have a very large effect on the viscosity of a fluid. the bath temperature for most high temperature measurements, 40 degrees C and 100 degrees C, must be controlled to within +/- 0.002 deg. C and for low temperatures, typically -20 deg. C and -40 deg. C, a stability of +/- 0.05 deg C is required. That is an extremely tight window and great care must be taken to achieve this control.

Lawler Model 86-20 High Temperature Viscosity Bath is designed with tight 0.02 degree temperature stability in mind. Instead of an open bath jar, an enclosed cabinet design is used to prevent room drafts from affecting temperature. And more importantly, a sophisticated process grade temperature controller is used with 0.01 degree resolution. It is the only one on the market used with such resolution. Other units use 0.1 degree resolution controllers which make it impossible to verify the 0.02 or even 0.05 degree stability requirement. http://www.lawlercorp.com/d445_high.html

Lawler Model 70 Series Low Temperature Kinematic Viscosity Baths are similar and additionally are built with Lawler's advanced refrigeration system to reach temperatures as low as -70 degrees C with +/-0.05 temperature stability or better. http://www.lawlercorp.com/D445_1_UK.htm

ASTM D2983 Low Temp. Brookfield Viscosity Spindle Clips

At the suggestion of a customer many years ago, there is a very simple and inexpensive method to making the spindle suspension clips using an ordinary paper clip. Cut the paper clip per this drawing.

Water Separability Paddle Cleanliness

With all the concern for cleanliness of the glassware for this ASTM D1401 test, it was recently discovered that the paddle itself may cause cleanliness problems. Most paddles are soldered to the shaft. It is unclear how to thoroughly clean soldered edges. To eliminate any possibility of impurities, the paddle and shaft should be one piece of metal. Lawler supplies a one piece paddleand shaft to address this concern. Learn more about out D1401 Water Separability bath here: http://www.LawlerCorp.com/d1401.html

Water Separability Testing Advice

Extreme care should be taken to use very clean, unscratched, un-etched glassware in this test method. Carefully examine the cylinder. Discard it if any sign of residue, etching or scratching is noted. Before using, the glassware should be checked for cleanliness by adding reagent water to the cylinder and inverting it to drain. If the water is drained by a smooth sheeting action and leaves behind no droplets, the glassware is clean for use.

Please visit the Lawler page for our Model 305 Water Separabilty Apparatus: http://www.LawlerCorp.com/d1401.html