Diffuser Certification Apparatus for Foam Testing of Lubricating Oils

ASTM D892 . ASTM D6082 . ASTM E128

  • Description
  • Features
  • Configuration
The measurement of Foaming Characteristics of Lubricating Oils per ASTM D892 foam testing, and ASTM D6082, High Temperature Foam Testing, is dependent upon the gas diffuser stone used in the test. Certification of the diffuser stone involves the determination of critical parameters including MAXIMUM PORE DIAMETER and PERMEABILITY for either spherical ceramic (Norton stone) or cylindrical metal (Mott) diffusers.

ASTM D892 recommends that the diffusers be tested when new and periodically thereafter, preferably after each use. ASTM D6082 requires the recertification of the diffuser after 10 foam tests.

The measurement of Foaming Characteristics of Lubricating Oils per ASTM D892 foam testing, and ASTM D6082, High Temperature Foam Testing, is dependent upon the gas diffuser stone used in the test. Certification of the diffuser stone involves the determination of critical parameters including MAXIMUM PORE DIAMETER and PERMEABILITY for either spherical ceramic (Norton stone) or cylindrical metal (Mott) diffusers.

ASTM D892 recommends that the diffusers be tested when new and periodically thereafter, preferably after each use. ASTM D6082 requires the recertification of the diffuser after 10 foam tests.

• Fully automated and manual apparatus 
• Certifies diffusers used in ASTM D892 and D6082
• Determine maximum pore diameter and permeability
• Conform to ASTM E128


Model FM-19PC Digital Diffuser Certification Apparatus automatically determines both diffuser PORE DIAMETER and PERMEABILITY in accordance with ASTM E128. However, the manometer is replaced by a high precision digital pressure controller. Furthermore, the traditional analog flow meter is replaced by a digital mass flow meter that directly interacts with the software.

The automated pressure ramping profile generates the Dynamic Bubble Point pressure that is used to determine Pore Diameter of stainless steel and ceramic diffusers. This is calculated by the software program. The steady pressure holding profile generates the permeability of the diffuser in mL/min. Both results are automatically displayed on the computer screen.

The Lawler proprietary Windows software manages the testing operation and all the data. The data can be printed and/or stored on the PC hard drive for ISO 9000 trace ability.

Model 18PC is identical to Model FM-19PC, above, but required visual observation for the appearance of the first bubble.

Model FM-18PC Diffuser Stone Certification Apparatus is a compact unit measuring 11 x 13 x 8 inches.

Model FM-18D is a non-automated apparatus, also conforming to ASTM E128 for measurement of pore diameter. It consists of a certified (NIST traceable) U-tube manometer capable of reading 1000 mm of water installed on a wall mountable stainless steel panel, a 250 ml graduated cylinder, a precision regulating valve and a 1 meter length of 8 mm plastic tubing.

Mounted on the same panel is the apparatus for the determination of permeability which consists of a digital indicating mass flow meter capable of measuring 6000 ml/min. air flow while generating a low back pressure, and an Erlenmeyer flask with rubber stopper.

Model FM-18D eliminates the need for the clumsy and difficult to use wet test meter.

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Diffuser Certification Apparatus for Foam Testing of Lubricating Oils
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