Volumetric Measuring Tool
Volumetric Measuring Tool
(OP)
Is anyone aware of an inexpensive tool or device that will allow me to measure the volume of an irregular shaped space (i.e. glove box)? The tried and true method of ping-pong balls is not very accurate and is difficult to perform on vehicle cabinets that are open in the vertical position.





RE: Volumetric Measuring Tool
Or put a plastic bag in the volume and spray in foam. Remove bag and measure foam by water displacement or by weight (1 cubic ft foam weight .76 pounds, the foam block weights 1.52 pounds, the volume is 2 ft^3).
If one dimension is linear, then measure the area of the irregular by graph paper or weight and multiply the area by the linear dimension.
RE: Volumetric Measuring Tool
Do you have the part by itself? If it is a glovebox, I would seal it and submerse it in water. Just measure the volume of water displaced.
I don't know how accurate of a measurement you need, but keep in mind that the above method will include be the exterior volume, not the interior volume of the glove box.
-Reidh
RE: Volumetric Measuring Tool
If only the volume of air could be measured like water we could place a baloon type device in the empty compartment and inflate it to fill all the voids. Any thought along these lines?
RE: Volumetric Measuring Tool
Where's the complication in this method? How accurate would you need?
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Volumetric Measuring Tool
Get a 'Balloon', it will need to be a fairly tough one which when fully inflated is quite a bit bigger than the space you are measuring.
Place in glove box (or whatever).
Almost close glove box, leave open just enough to either pull the 'valve' of the balloon out or maybe put some small dia tubing to the balloon.
Inflate the balloon to just over atmosphere. You want it to take up all the room but not build up much excess pressure. It may be better to evacuate the air from between the outside of the balloon and the walls of the glovebox but making a seal like this may be difficult.
Seal balloon.
Pull out the 'inflated balloon'.
Imerse in water, the water needs to be up to the top of the pan or spigot. You need to make sure and not immerse it too far or the water pressure will compress the air. I'm thinking a large but shallow pan. Maybe push the balloon down with a large board or something so it can spread out but not be submerged too far.
Measure the displaced water.
I'm pretty sure I missed something.
If the water insists on compressing the ballon you could put a pressure gauge on the balloon to see how much and compensate to adjust the volume.
The balloon wont actually be a ballon, I'm thinking something like the heavy duty bags they use in shipping or something.
Sounds mighty complex, someone must have a better idea.
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
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RE: Volumetric Measuring Tool
If you use the pressure gage you don't have to worry about how far under the water you immerse it etc.
p1v1/t1=p2v2/t2 as I recall.
There must be a better way though.
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
You stated "Inflate the balloon to just over atmosphere"
What difference does the inflation pressure make?
Reidh
RE: Volumetric Measuring Tool
I propose measuring the volume by displacing water.
If you don't use the pressure gauge then as air is compressible the water pressure would compress it as the balloon is submerged this would effect your volume measurement.
If you compensate for pressure difference with a gage reading both in the glove box and submerged in water then you're home free and can inflate to well over atmosphere to fill the gaps.
I'm thinking filling macgyvers2000 bag with dcastos balls (only maybe the really small ones like in bean bags) may be a better idea.
(macgyvers2000 & dcasto, that wasn't a joke at your expense)
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Volumetric Measuring Tool
From this, you could calculate the mass of air in the glove box, the density of the air in the glove box, and thus the volume of the glove box.
This would be a huge pain to perform, and you would need fairly accurate measuring equipment. But if you have an excess of time and money, I would highly recommend this method.
-Reidh
RE: Volumetric Measuring Tool
2. Squirt expanding foam sealant into the cavity. I suppose that I would try to get the softest version of that stuff from the <Home> supply <Depot> store or equivalent.
3. Cut out the foam block without destroying too much of the volume.
4. Put foam pieces into a container of known volume.
5. Fill the container to the level mark with water.
6. Remove the foam blocks.
7. Do the math: Max- Remainder = Cavity Volume.
TygerDawg
Blue Technik LLC
Advanced Robotics & Automation Engineering
www.bluetechnik.com
RE: Volumetric Measuring Tool
When you get the data what are you going to do with it??
RE: Volumetric Measuring Tool
Our vehicle has 25 cubic feet of storage, the competitor only 19.
Or use it as a design target to exceed for the same reason.
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
Not the most accurate of methods, but I figure it would get you close enough?
RE: Volumetric Measuring Tool
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Volumetric Measuring Tool
RE: Volumetric Measuring Tool
You can also estimate the packing efficiency of any size sphere.
This really isnt that complex, it all depends on the accuracy that you need from teh measurement, I'm sure that 1/4" beads would provide accuracy to <0.25ft^3.
I wouldnt use styrofoam, the static charges would just be annoying.
RE: Volumetric Measuring Tool
What I didn't make clear before:
Seal bag, 'burping' excess air.
Place bag in displacement tank, no need to measure packing efficiency.
Ta-da.
So what did I miss?
You maybe be able to do the same with sand but it will be heavy, and if the bag tears will be more difficult to clear up, probably.
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Volumetric Measuring Tool
RE: Volumetric Measuring Tool
Use air to inflate a very thin plastic bag (e.g., garment cover from the laundry) into the volume so it is filled. Inflate to a known pressure, perhaps 10 inches water column (w.c.) to fill the void, then deflate to 1" w.c. Then use a simple syringe to inject a known additional volume of air (e.g., 100 ml). Measure the pressure increase, say 2" w.c.
From the known volume of air injected into the unknown volume of the bag and the measured pressure change you can easily calculate the unknown volume. Correction should be made for temperature changes.
A slanted tube mannometer can accurately and inexpensively read measure these pressures. No mess to clean and gravity is not a problem.
RE: Volumetric Measuring Tool
Regards
eng-tips, by professional engineers for professional engineers
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RE: Volumetric Measuring Tool
How about hand held laser scanners. There is at least one, possibly more, on the market which I believe allow you to scan an items geometry and then create a solid model from it.
It should then be possible to interrogate this model to get a good approximation of the volume.
Not sure if it would work for your kind of thing but worth looking into? I had an email with some details but can't find it now.
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
1. Tracer gases -put a known quanity of gas into your volume and then measure the concentration (by some electronic detector means).
2. Leak detector technology that use gases
Maybe these people(or similar companies) could give you some guidance.
h
RE: Volumetric Measuring Tool
RE: Volumetric Measuring Tool
RE: Volumetric Measuring Tool
Often small parts are 'counted' by mass rather than unit. Several hundred ping pong balls should be weighable on a tabletop balance. If you use competition-grade balls (??) they should be very uniform mass.
If loading them into vertical compartments is too tedious then you should employ more engineering interns.
RE: Volumetric Measuring Tool
The heavier the material the better as any scales large enough to take a campervan is likely to have a poor resolution.
RE: Volumetric Measuring Tool
No kidding! As a consumer, not an engineer, I would say the total volume is not the metric anyway; it's how useful the shape is, how accessible, how well lit, etc. If one glovebox is 2 cu. inches bigger but it's an odd shape that collects lint and is hard to clean, I am not impressed. Not that I've ever even looked at a glovebox when considering a purchase....
RE: Volumetric Measuring Tool
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Volumetric Measuring Tool
KENAT, probably the least qualified checker you'll ever meet...
RE: Volumetric Measuring Tool
In some cases, I just put the bag in the cavity and fill it with sand. For more progressive curves and cavities that does the trick. If you have oddly convoluted shapes, what I suggest is using a light-duty "repositionable" spray adhesive on the bag. Then you can poke it into odd shapes and have it hold in place. If you don't, you can't be assured that the bag is fully displacing.
To add accuracy, I will use an air hammer with a custom-made flat anvil to settle the sand, then after I pour the sand in a measuring vessel I use the air hammer again to make sure its leveled out similarly.
Perfect? no. Super close? yes.