fullness factor 1

[kingnero]

I need to have an estimate of the weight of a container, filled with several pieces of the same material, however each piece is different in dimensions and totally random as well.

If i could guess the fullness factor of the container, I could calculate the weight using the density (specific gravity?) of the material.

Filling the container with water and measuring the used volume, is not an option.

Any ideas?

 

[drawoh]

kingnero,

How about you fill a small container with the pieces and count the number you got in? This would tell you approximately how much volume each piece takes up.

JHG

 

[vpl]

You might Google "estimating number of jelly beans".

Same concept.

Patricia Lougheed

******

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[kingnero]

@ drawoh: pieces are too different in size (and there are too much of them) in order to get an "average".

@ vpl: have read it, and the idea is good, however they mention:
It can be assumed that 20% of a given volume is air rather than jellybeans
How one finds out that specific value, would be my question...

 

[JStephen]

Looks to me like a guess as to the percentage is as good as you're going to get.

Assuming you can't find someone with the experience to say differently, that is. People that haul scrap iron, for example, would have a pretty good idea of what a given volume of scrap of one kind or another would weigh. Steel mills might have good values for the material they process as well.

 

[kingnero]

Looks to me like a guess as to the percentage is as good as you're going to get.

I know, I am hoping for a method or a way to make a more educated guess regarding the fullness factor.

This must have been done before, and indeed it's scrap metal I am talking about.

 

[CorBlimeyLimey]

"pieces are too different in size (and there are too much of them) in order to get an "average"."
On the contrary, under those conditions, the only thing that can be done is to get an average.

Obviously, the best method would be to weigh some full loads ... but I assume that's not feasible.

 

[rb1957]

do you want an average, or a maximum, load ?

i assume you want to limit the load to some maximum. i'd pick a number and assume a relatively high cg (if that matters to you).

question ... do you see the guys loading the scrap iron weighing each piece, or the total load ? i'd interpret my maximum load in terms that these guys can apply (a single "man" (non-gender specific) can lift 50 lbs as a maximum, but many pieces would be smaller 25 lbs ?; two guys can lift 100 lbs pieces ...)

 

[IRstuff]

Why can't you do an Archimedes experiment?

Can you use some medium than water, say sand, or beads?

TTFN

FAQ731-376

 

[kingnero]

I need to get an estimate of the weight in order to choose a method of transportation (trailor, truck with a single rear axle or one with a double axle). And to have an idea what it would be worth, as it's actually cupper and alloys.

@ CorBlimeyLimey: some pieces weigh over 50 lbs, and others are small fasteners. and many pieces of all sizes inbetween.
About 15% is tubing, valves, and such, thus hollow pieces.
How would I start picking, let's say: 100 pieces, and weighing 'em in order to get the average weight or volume?

 

[ivymike]

maybe the civil engineers have a method for calculating packing density.

 

[ivymike]

I don't know what sort of size range you're talking about - if you have extremely big pieces and extremely small pieces, then you'll need to come up with different "average" densities for each of several buckets of item sizes.
Alternatively, you could melt, shred, or crush it all to homogenize the density.

 

[MintJulep]

This seems a variation of the bin packing problem which is well documented.

The key difference is that most bin packing algorithms are built assuming that the size of the individual items is known.

You would need to develop an item size distribution to feed an algorithm.

 

[rb1957]

are you trying to limit the loading of the skip ? if they fill the skip with small items it'll be damn heavy, if they toss just a few bulky items into it it'll be light. i think you're asking a bit much to get the guys tossing the stuff a understand and notice the difference between copper, (Al) alloy, and steel (if you're trying to estimate the value of the load) ... but you know the guys better.

is it impractical to weigh the skips ? (put a heavy duty scale on a fork-lift and weigh one end, or both) that'll get you the most accurate weight.

alternatively, i suspect that the guys tossing the stuff (and particularly the guys who have been doing it for number of years) probably have a pretty good idea on how much a load weighs.

 

[CorBlimeyLimey]

@ CorBlimeyLimey: some pieces weigh over 50 lbs, and others are small fasteners. and many pieces of all sizes inbetween.
About 15% is tubing, valves, and such, thus hollow pieces.
How would I start picking, let's say: 100 pieces, and weighing 'em in order to get the average weight or volume?

You wouldn't. As I mentioned above the best way would be to average a few full loads. Do you not have a truck scale on site? If not is there a local transport weigh-station that could be used?

 

[IRstuff]

OK, so why not simply place these containers on a scale, while loading, and stopping loading when you reach your weight limit?

TTFN

FAQ731-376

 

[dvd]

Although it will give a lot of false hits due to multiple definitions for porosity, I think a search for "porosity of scrap iron" would yield results. I found this one rather quickly:

http://www.springerlink.com/content/gh874233qrh292h2/

looks like you have to buy the paper to learn the whole story...

 

[kingnero]

Weighing is not an option as all the skips are at my home/workshop, I do not have the facility to weigh those, let alone weighing the vehicles until they reach their max load.

each skip is filled with the same material (eg, 1 with Cu, 1 Al, 1 with 304 and 316, and a few with scrap iron) so no need to sort any further when loading.

Judging by eye, I have a 1/3 air to material ratio, I will go using that, and rounding up when hiring transportation...

many thanks for all the replies...

 

[JStephen]

"question ... do you see the guys loading the scrap iron weighing each piece, or the total load ?"

They haul it to the scrap metal place, weigh the truck loaded, dump it, and weigh it empty.

With a dump truck hauling scrap structural steel, you can't fit anywhere near a full load on. That is, it weighs less than the sand or gravel you might otherwise haul. If you had a lot of small items mixed in, you might get the weight on up there.