This is a very good presentation. Unfortunately, ASTM D422 was discontinued several years ago and was replaced with ASTM D7928. The sample preparation portion (0:00 - 5:50) appears the same. I don't think you should use your bare hand while mixing - induces contaminants. The mixing time / rate of inversions should be checked - I've heard both 60 cycles for 1 minute and 30 cycles per 1 minute. I would have liked to hear a bit more discussion on the miniscus correction - is this due to the difference between the top and bottom of the miniscus or due to the difference in specific gravity of distilled water at 20 degrees C and the sample? Is the sample to come to 1,000 ml before, or after the hydrometer is placed into the cylinder?
Great explanation. A bit more explanation about hydrometer correction would have been really useful. I always get confused on them.
thanks you for this simple and clear method in explaining
This is a very good presentation. Unfortunately, ASTM D422 was discontinued several years ago and was replaced with ASTM D7928.
The sample preparation portion (0:00 - 5:50) appears the same. I don't think you should use your bare hand while mixing - induces contaminants. The mixing time / rate of inversions should be checked - I've heard both 60 cycles for 1 minute and 30 cycles per 1 minute.
I would have liked to hear a bit more discussion on the miniscus correction - is this due to the difference between the top and bottom of the miniscus or due to the difference in specific gravity of distilled water at 20 degrees C and the sample? Is the sample to come to 1,000 ml before, or after the hydrometer is placed into the cylinder?
You are very good teacher
i still have an issue plotting the results from the hydrometer and seive analysis on the same graph. Any help with that?