hannahw1850
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Joined: Thu Jul 05, 2018 2:18 pm

Measuring an internal distance

Thu Jul 05, 2018 2:20 pm

Hello, I am currently working on measuring a change of diameter in a tube of 10mm diameter. Are there any very small sensors which can be placed in the tube to measure the small change? The change is usually around 2-4mm. It is closed off also so a vernier cannot be used to measure this. I'm after an accuracy of approximately 0.1mm.

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Z80 Refugee
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Re: Measuring an internal distance

Thu Jul 05, 2018 3:14 pm

To need to do this, you presumably desire to work out the pressure within the tube. Just use a pressure sensor and be done with it.
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drgeoff
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Re: Measuring an internal distance

Thu Jul 05, 2018 3:59 pm

The pressure sensor is a good approach if the tube remains of constant cross-sectional shape. But not if it does not. For example, changing from circular to oval.
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jamesh
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Re: Measuring an internal distance

Thu Jul 05, 2018 4:16 pm

Z80 Refugee wrote:
Thu Jul 05, 2018 3:14 pm
To need to do this, you presumably desire to work out the pressure within the tube. Just use a pressure sensor and be done with it.
Might want to measure the strength of the tube, and already know the pressure, wanting to know the strain.
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mark3112
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Re: Measuring an internal distance

Fri Jul 06, 2018 3:46 pm

Possibly a dumb question but I’m curious. Why do you need to measure the inside diameter?
As the pipe expands, the outside must expand as well. OK, the wall diameter will reduce very slightly but would make measuring easier.
If you can measure the outside, see laser diameter gauge (scan a laser across the target and the shadow period gives you the diameter).
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