Dear all
what Are the factors that can affect the air release value of fresh oil(additves or base oil) and how? and Can i compare ASTM results with IP results
regards
Original Post
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Summary of Test Method by ASTM D 3427-03
Compressed air is blown through the test oil, which has been heated to a temperature of 25, 50, or 75°C. After the air flow is stopped, the time required for the air entrained in the oil to reduce in volume to 0.2 % is recorded as the air release time.
The speed at which the air bubbles rise to the surface depend on the diameter of air bubbles, the viscosity of the fluid, density and also the quality of base oil.
Usually I see IP logo beside ASTM logo in the first page of ASTM document, that means these two method is comparable, but for ASTM D 3427 I didn't see the IP logo. May be because the difference in temperature condition. IP 313 tested at 20, 50 and 100 °C.
For New Oil, I recommend to test Foam Characteristic (ASTM D 892)also. If the problem still occur with this test, it mean the defoamant additive is ineffective.
CMIIW
regards,
Nurudin
Compressed air is blown through the test oil, which has been heated to a temperature of 25, 50, or 75°C. After the air flow is stopped, the time required for the air entrained in the oil to reduce in volume to 0.2 % is recorded as the air release time.
The speed at which the air bubbles rise to the surface depend on the diameter of air bubbles, the viscosity of the fluid, density and also the quality of base oil.
Usually I see IP logo beside ASTM logo in the first page of ASTM document, that means these two method is comparable, but for ASTM D 3427 I didn't see the IP logo. May be because the difference in temperature condition. IP 313 tested at 20, 50 and 100 °C.
For New Oil, I recommend to test Foam Characteristic (ASTM D 892)also. If the problem still occur with this test, it mean the defoamant additive is ineffective.
CMIIW
regards,
Nurudin
Air release is typically a function of the base oil. If the base oil does not have good air release, there are no additives that I am aware of that will ever help, in fact some of the additives introduced to improve other properties may inhibit good air release.
I'd be very circumspect about equating foam (super-surface air bubbles) with air entrainment (sub-surface air bubbles). Foam is treatable, but an excess of antifoam additive can cause air entrainment (poor air release).
I've got a bit of background with both ASTM D 3427 & D 892. I've not identified any correlation, except as noted; additizing to help foam can degrade air release.
Antifoam additive cannot become ineffective, since its function is a physical rather than chemical phenomenon. It can fall out of suspension or become overwhelmed by foam-inducing contaminants (usually fine particulates), but the molecule does not degrade chemically like an antioxidant or antiwear additive will.
Methacrylates are less prone to causing air entrainment, but don't seem to suppress foam as well as siloxanes, which in turn are real bad actors when it comes to air entrainment.
I'd be very circumspect about equating foam (super-surface air bubbles) with air entrainment (sub-surface air bubbles). Foam is treatable, but an excess of antifoam additive can cause air entrainment (poor air release).
I've got a bit of background with both ASTM D 3427 & D 892. I've not identified any correlation, except as noted; additizing to help foam can degrade air release.
Antifoam additive cannot become ineffective, since its function is a physical rather than chemical phenomenon. It can fall out of suspension or become overwhelmed by foam-inducing contaminants (usually fine particulates), but the molecule does not degrade chemically like an antioxidant or antiwear additive will.
Methacrylates are less prone to causing air entrainment, but don't seem to suppress foam as well as siloxanes, which in turn are real bad actors when it comes to air entrainment.
