Seleing heavy gas for instrument diplay purge

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SUMMARY

The discussion focuses on selecting an appropriate gas for purging an outdoor display unit to prevent condensation and oxidation. The participants consider using R134a, Argon, and CO2, weighing their effectiveness and practicality. R134a is noted for its heaviness, while Argon is suggested as a viable alternative. Nitrogen is mentioned as a common choice for dispelling oxygen, but its lighter-than-air property raises concerns for gravity filling in the device.

PREREQUISITES
  • Understanding of gas properties, specifically density and moisture absorption
  • Knowledge of condensation prevention techniques in electronic displays
  • Familiarity with R134a and Argon gas applications
  • Basic principles of environmental control in assembly processes
NEXT STEPS
  • Research the moisture absorption characteristics of R134a and Argon
  • Investigate the use of CO2 for purging applications in electronics
  • Learn about nitrogen purging techniques and their effectiveness in preventing oxidation
  • Explore environmental control methods for assembly in humid conditions
USEFUL FOR

Engineers and technicians involved in the design and assembly of outdoor electronic displays, particularly those focused on preventing condensation and ensuring product quality in varying climates.

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We are working on an outdoor display unit. It will operate at a wide range of temps. There is not a requirement to purge air from the encasement but would be a smart decision I think. my thought was to use a gas that is very dry and heavy enough to simply purge the air and sit in the device like water while the sealed lens is installed.

These are being made in small qtys and volume is less than 1in3 each. Thought was to use R134a since it is a very heavy gas but wondering if that is really an overkill for this. Argon might work just as well and we have both in the shop. Not sure if either will readily absorb moisture from the air for the few minutes they would be sitting until sealed. A cheap and easy solution might be CO2.
 
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What's the purpose of the purge? If you're looking to dispell oxygen to prevent oxidation of anything inside, I've seen nitrogen most commonly used.
 
Condensation in certain cold weather conditions is our primary concern. It would not affect our circuits at all but does not project an image of quality. N is lighter than air so that would not fit our gravity fill considerations here. We are in a fairly humid climate several months out of the year so have a dry gas fill would hopefully be a quick easy step to ensure a quality display in cold temps.
 
You could always do the assembly in a low humidity room (environmentally controlled, RH & Temp, walk-in chamber).
 

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