Volumetric Measuring Tool

[mcpdx]

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.

 

[MacGyverS2000]

Guys/gals... the OP made only two posts within two hours of each other, and nothing for nearly three weeks. I think we could say this thread is dead.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[mcpdx]

I am still following the feedback here. However, I've yet to see a solution that is either easy to execute in the field or simpler than the ping-pong ball or bean-bag appraoch. Unfortunatly, I am going to be measuring the interior cabinet space of heavy-duty trucks and motor homes, both of which have some very large and very irregular storage cabinets. In some cases, I would have to use several hunderd ping-pong balls and counting these would be really impractical.

 

[Compositepro]

Use the principle of the helium pyncnometer which will measure the true density of sand particles or just about anything else.

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.

 

[patprimmer]

A measuring tape and a bit of reasonable estimation can actually get you quite close most times.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[KENAT]

OK, so you don't like the water displacement idea (in any of its forms).

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...

 

[amorrison]

Think

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.

http://www.lowener.se/e/Helium leak testing systems.htm

 

[MintJulep]

Empty cardboard boxes for the bulk of the space and ping-pong or Styrofoam balls for the remainder.

 

[Wicsteve]

How about pouring semi-flexible foam into the cavity (inside a bag). After the foam sets, remove the foam (either in one piece or in sections). Bag the foam. Measure the volume by displacing water in a bucket of water (measuring by weight of displaced water or measuing the volume of overflow.

 

[drwebb]

"counting these would be really impractical"

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.

 

[richkeogh]

Place the vehicle on a huge scales, then fill the compartment with a material of known density and re-weigh.
The heavier the material the better as any scales large enough to take a campervan is likely to have a poor resolution.

 

[RossABQ]

"A measuring tape and a bit of reasonable estimation can actually get you quite close most times. "

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....

 

[GregLocock]

There is an ISO standard collection of luggage for that very reason.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[KENAT]

http://zcorp.com/documents/112_ZScanner-singsheet-v08.pdf

KENAT, probably the least qualified checker you'll ever meet...

 

[curtis74]

I have used sand in a garbage bag many times before to measure cavities into which I wish to build speaker enclosures. In the case of audio work, getting really close was good enough, but if you just want a 98% estimate, use sand.

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.