Flashpoint Testing Method ASTM D-92 vs. ASTM D-93

[silverbullet]

Does anyone know what the difference is in the test methods between the two?

I recently checked the Dino Pennzoil 5w30 flashpoint as 216 deg. F (ASTM D-93) and Pennzoil Platinum 5w30 flashpoint as 196 deg. F (ASTM D-92).

At first I thought, why would the Dino Pennzoil have a that much of a higher flashpoint than their "best" Platinum line. Then I realized the test methods were different. So it led me to the question of what's the difference in the two methods?

 

[Blue99]

ASTM D-92 is the Cleveland Open Cup test.

ASTM D-93 is the Pensky-Martens Closed Cup test.

The closed-cup method prevents vapors from escaping and therefore usually results in a flash point that is a few degrees lower than in an open cup.

Base oils typically are 220C+ flashpoints, so it is the volatility of an additive that is producing the lower flash in a fully formulated motor oil.

 

[Primus]

D-93 value is usually about 20 deg C lower than that of D-92

 

[bruce381]

All correct and to add I have always used the PMCC for flash under 200F for light distillates.
bruce