Measuring Density

Triple beam balance and a beaker of water. Actually, any weighing device rigged to support the sample in the beaker will work.

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Do these Flowmeters check for density? Plus what we are checking has the consistency of Play dough.

Thank you,

Tom

one of the many Spammers that appear from time to time

Alternatively, weigh the sample in air, and measure the volume by immersion in fluid in a measuring cylinder.

If it's soft like play-do, he could simply pack it into a graduated metric cylinder of known volume. First 'weigh' the cylinder empty to get its mass (or zero the scale to eliminate the tare) and 'weigh' it a second time when filled with the gel to get the mass of the gel. No need for water in this case.

Simektp was posting this in reference to a question that I had asked him this morning. We have tried that method but the gage R&R fails because the repeatability of measuring it that way is poor. The water seems to work well, but the measurements from the beaker or cylinder are difficult to repeat as well, even at 1ml increments.

If you combine Lyn and JD you have the technique.

Weigh a sample suspended on a fine wire, or similar, in air

Fill a measuring cylinder partially with water to a noted level.

Lower the sample to submerged.

Note the new water level and new weight.

New level is the sample volume

New weight is the % change

'Variables' will be temperature, wire volume (if you go too deep) and possibly air inclusions in the sample (so you may wish to vacuum desiccate a "putty" prior).

You should use as large a sample as practical to fit the cylinder - not some tiny piece.

Actual sample size need not be precise, or consistent - just fit freely, not sit on the bottom and not cause water rise above the scale.

Why weigh it in water? If you know the weight in air, and the volume (from the cylinder graduations) you have the answer. The difference between this result and your method would only give the error due to the 'buoyancy' in air, which - for a lump of clay - would be negligible compared with the other errors (some of which you've mentioned).

_{(Why do so many people put quote marks around the word weigh? Is there something wrong with it about which I do not know?)}

HEY - ADMIN! - any way of merging the two parallel threads with the same name? - would make life a lot easier for all concerned. I'm pretty sure the two OPs who work together wouldn't mind. ^{_{(Pretty please? :) )}}

The procedure being described sounds like specific gravity

like this http://www.mineralab.com/Hanneman.html

a couple of other types

http://www.mineralab.com/Specific%20Gravity.htm

Spot on - but SG wasn't in the subject line.

OK - if you know one, you can calculate the other - but dry weight and wet volume measurements sound easier to me than trying to weigh something suspended on a string in a bucket.

Well Mr Grumpy, it depends (somewhat) on why they want to know (also not clear in the OP). E.g. for development, or QA?

But, by doing it two ways in the same protocol - the results aught to line up. If they don't then there is something wrong with the procedure, or apparatus, or sample - I.e. contamination, or a void (spare parts, cockroaches, ...)

It's just a little foible of mine to build some 'self checking' into test protocols.

Saves a lot of time "chasing anomalies" if you can see a result is "odd", straight off the bat.