- Apr 14, 2005
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How big is a milliliter....I mean is it 1 eyedrop like from an eyedroper or is it the whole eyedroper (Which seems to hold around 5 drops)
thanks
thanks
Originally posted by: CHOPPER GOD
How big is a milliliter....I mean is it 1 eyedrop like from an eyedroper or is it the whole eyedroper (Which seems to hold around 5 drops)
thanks
(That gives a median of 48.6 microliters.)Found on the abstract:
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=10396391&dopt=Abstract
33.8 microliters to 63.4 microliters
Conversion Table for Weights and Measures
http://www.peteducation.com/category_summary.cfm?cls=0&Cat=1305
1 drop = 1/20 mL
Originally posted by: CycloWizard
Generally, the rule of thumb is 20 drops per mL (as kevin showed above).
If you're an average person, you can stop reading. However, if you're an HT regular, the size of a 'drop' will depend on the substance you're dropping and the material that the dropper is made from. A drop is formed when surface tension forces between the fluid and the dropper exceed the shear forces of the fluid flowing down the dropper. Because the size of a drop is not constant, it's not necessarily correct to say that 20 drops is 1 mL. This correlation has been developed for water in most glass or plastic containers though and does stand up to muster as long as your materials are not too strange.
A PhD student in mechanical engineering here just published a paper on predicting droplet pinchoff using a relatively simple mechanical model similar to what you described. I'll see if I can track it down... The experimental setup he used was a microfluidic device that had an applied pressure gradient with a feed of liquid A on one side and fluid B on the other. Since the pressure gradient and dimensions of the system were all known, he couldOriginally posted by: kevinthenerd
In true HT fashion...
Yes. Let's assume earth's gravity and the air pressure aren't changing so the specific weight and surface tension aren't changing for a given substance. Let's also assume that you have a constant dropper size to keep things scientific. We're holding it at a constant angle to neglect the effects associated there too.
Surface tension force goes up in a linear fashion with an increase in radius (because it essentially goes up with the circumference) but weight goes up in a cubic fashion (because it essentially goes up with the volume). The point at which these two forces overcome one another is the time when the drop drops, but that's not quite complete either. The drop size changes as the volume increases. Initally, your liquid is entirely supported at the dropper's radius, giving it a very good radius of surface tension for a comparably low volume, but eventually it elongates to almost form a sphere before it drops. I would suppose a good combination of CFD and FEA would be appropriate here, and I'm not even sure if you can assume steady state analysis unless you're holding the dropper very still and squeezing very slowly.
My department (chemical engineering) does lots of work with bubble columns, so I get to see lots of seminars on this stuff. There are some pretty strange things people do with bubbles. Especially the guys from Holland.This reminds me of the difficulties in predicting bubble density for my studies in pool boiling heat transfer on a horizontal plate with vertical normal orientation. The surface tension at the nucleation between the fluid and the vapor is what causes it to stay close to the heated wall before releasing, and while it's sitting there the wall has to superheat quite a bit before it goes anywhere. (When it does release the cooler liquid can quench the wall.) Surface tension has big effect on bubble size. Studies have been done on the effects of surfactants on convection heat transfer coefficients and on the critical heat flux.
Originally posted by: Witling
Actually, in general, 1 ml is not the same as one cubic centimeter, depending on how exact you want to get. One mililiter is defined as one cubic centimeter of water at 4 degrrees centigrade (the point at which water is most dense).
Originally posted by: Witling
Actually, in general, 1 ml is not the same as one cubic centimeter, depending on how exact you want to get. One mililiter is defined as one cubic centimeter of water at 4 degrrees centigrade (the point at which water is most dense).
Found in the PDF by Kimble Kontes, an ISO compliant company that makes laboratory glassware
http://www.kimble-kontes.com/pdfs/milliliter_cubic_centimeter.pdf
MILLILITER VERSUS CUBIC CENTIMETER
The Twelfth General (International) Conference on Weights
and Measures redefined the liter as, ?a special name for the
cubic decimeter?. Thus, the relationships previously used ?
1 liter = 1.000028 cubic decimeters, and
1 milliliter = 1.000028 cubic centimeters, became void.
The Conference did agree that use of the terms ?liter?,
?milliliter?, and ?mL?, might be continued, except in association
with measurements of the highest precision. Incidentally, the
preferred abbreviation for cubic centimeters is ?cm3? ? the
use of ?cc?, is not permitted.
The difference in volume between the old and the current
meanings of liter is so small as to be negligible for volumetric
glassware. This being so, we continue to use ?liter? and
?milliliter? in catalog descriptions and for inscriptions on glass
apparatus. In the worst case, that of a 2000 ?milliliter? flask, the
difference is only 10% of the Class A tolerance.
Originally posted by: Witling
Actually, in general, 1 ml is not the same as one cubic centimeter, depending on how exact you want to get. One mililiter is defined as one cubic centimeter of water at 4 degrrees centigrade (the point at which water is most dense).
Originally posted by: Golgatha
Originally posted by: Witling
Actually, in general, 1 ml is not the same as one cubic centimeter, depending on how exact you want to get. One mililiter is defined as one cubic centimeter of water at 4 degrrees centigrade (the point at which water is most dense).
This is the exact definition.
He looks like you've given him enough drugs already.Originally posted by: CHOPPER GOD
ok here is cat
http://i103.photobucket.com/albums/m149/Betteroffblind/kitty010.jpg
Originally posted by: CHOPPER GOD
ok here is cat
http://i103.photobucket.com/albums/m149/Betteroffblind/kitty010.jpg
Originally posted by: Witling
Actually, in general, 1 ml is not the same as one cubic centimeter, depending on how exact you want to get. One mililiter is defined as one cubic centimeter of water at 4 degrrees centigrade (the point at which water is most dense).
But 5 g of steel is much less than a milliliter. In your approach is the implicit assumption that density of the substance being measured is equal to that of water.Originally posted by: lyssword
well I usually think of ml as 1 gram. 5 grams or ml are in teaspoon. Mliters/liters are used for water or volume whereas grams/kilograms are used for measuring total weight, lets say a weight of a solid.