Among the quality supervision indicators of power oil, gear lubricant and construction machinery hydraulic oil, "foam characteristics (anti foam performance)" and "air release value" are two analysis items that often appear in parallel on the test report.

Since both involve the interaction of "oil" and "gas", many new equipment managers and even technical purchasers often confuse the two, and even misunderstand: "Since we have used the anti foam tester to measure oil products without large foam, why buy a separate Baoding Huazheng HZ-1034 lubricating oil air release value tester to measure the air release value? Isn't this testing the same thing? ”

The answer is completely different. In the colloidal chemistry and fluid dynamics system of oil products, foam characteristics and air release characteristics focus on the oil gas mixing phenomenon in completely different physical forms. There is even a natural "contradictory game" between the two in terms of mechanism, hazard and additive compatibility.

1、 The difference in physical form: "surface naked eye bubbles" vs "internal microscopic suspended mist"

Foam: refers to a group of large bubbles clearly visible to the naked eye floating on the free surface of the oil tank or oil pool. Its bubble diameter is usually above the millimeter level, and it is covered by a thin oil film on the outside, accumulating on the liquid surface. The main assessment is the ability of oil products to prevent foam accumulation, prevent oil tank from spilling and promote foam rupture on the liquid surface (tested according to GB/T 12579/ASTM D892);

Air Release/Mist Air: Refers to extremely fine bubbles (micron sized mist) that are completely submerged, suspended, and dispersed deep inside the lubricating oil. These microbubbles, due to their extremely low buoyancy, do not quickly float out of the liquid surface, but instead flow at high speed in a closed pipeline with the forced circulation of the oil pump. HZ-1034 is tested according to SH/T 0308/ASTM D3427, and it is precisely the ability of the oil to quickly desorb and release these "deep suspended microbubbles" upwards.

2、 Difference in Hazard Dimensions: "Oil Spill Pollution" vs "Fatal Cavitation and Pressure Shake"

Too much foam on the liquid level mainly causes oil overflow in the oil tank, false oil level in the oil level gauge and poor lubrication and cooling;

The harm caused by the inability to expel internal mist and bubbles is much more serious: when oil containing microbubbles enters the high-pressure area of a high-pressure hydraulic pump or turbine bearing, the bubbles are suddenly compressed by hundreds of atmospheres, resulting in adiabatic micro local detonation (diesel engine effect), and the instantaneous local high temperature can reach several hundred degrees, leading to rapid coking and carbonization of the oil product; At the same time, the rupture of bubbles under high pressure will erode metal blades and valve cores, causing fatal high-frequency micro cavitation peeling and instability of the speed control system.

3、 Game of additives: Adding too many defoamers can actually worsen air release

This is the core reason why the two tests must be paid equal attention to at the same time: many blending manufacturers blindly add macromolecular silicone defoamer to the oil in order to reduce the liquid level foam. Although silicone oil defoamers can reduce surface tension and promote the rupture of large bubbles on the liquid surface, they will adsorb around the interface of deep microbubbles, hindering the merging and enlargement of fine bubbles, and instead significantly slowing down the speed at which internal microbubbles float out of the liquid surface, seriously deteriorating the air release value of the oil product!

Only independent and precise air release value measuring devices like HZ-1034 can accurately monitor the healthy background of deep oil and gas separation in oil products, and build a safety barrier for high-end hydraulic and lubrication systems.