How to Waterproof a Strain Gage?

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Discussion Overview

The discussion focuses on methods to waterproof a strain gauge for underwater testing, considering budget constraints and the need for accurate data collection. Participants explore various sealing techniques and materials, as well as the implications of these methods on measurement accuracy.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about hermetically sealing a strain gauge without interfering with data, highlighting budget limitations.
  • Another suggests alternative methods to keep the strain gauge dry, such as using a balloon, plastic bag, or shrink wrap, and questions the sensitivity of the test to contamination.
  • A participant points out the distinction between a force gauge and a strain gauge, asking for clarification on the specific measurement needs.
  • One participant proposes that if the pressure is manageable, using silicone RTV to overcoat the strain gauge might not significantly affect strain readings.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of the strain gauge being in water and the effectiveness of various waterproofing methods. The discussion remains unresolved regarding the best approach to waterproofing while maintaining measurement accuracy.

Contextual Notes

Participants have not established specific requirements regarding water pressure and temperature, nor have they clarified the extent of contamination sensitivity in the testing environment.

Daniel Sadlier
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Hello all,

Our project needs to implement a force (strain) gage underwater for one of our tests. Our budget is pretty tight and we can't afford a wash-down strain gage that can support the forces that we will be operating at (~500 lbs).

Does anybody know a way to hermetically seal a strain gage and that doesn't interfere with the data? Or possibly a vendor that sells them for cheap?

Any help is welcome. Thanks!
 
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Just a thought, but does the strain gauge actually have to be in water? Could you have it in some kind of balloon or something? I don't know the details of your test. Can you simply have the strain gauge some how kept dry through some simple thing like a plastic bag or latex balloon or some such dodge? Maybe you can use shrink wrap that shrinks using a heat gun?

How sensitive is your test to the possibility of contamination? Could you use plasticene or some such thing? How much water pressure does the "water proofing" need to withstand?

https://www.amazon.com/dp/B00JM5GW10/?tag=pfamazon01-20
 
A force gauge and a strain gauge are different things - what do you actually need to measure ?

What is pressure and temperature of water to be sealed against ?
 
As long as the pressure is not too high, and the base material you are measuring is stiff (e.g. metal), you can probably overcoat the strain gage in silicone RTV without affecting the strain reading too much.