Seleing heavy gas for instrument diplay purge

In summary, the conversation discusses the development of an outdoor display unit that will operate in a wide range of temperatures. While there is no requirement to purge air from the enclosure, it is considered a smart decision. The suggestion is to use a dry and heavy gas, such as R134a or Argon, to purge the air and sit in the device like water while the sealed lens is installed. However, there are concerns about these gases readily absorbing moisture from the air. The possibility of using CO2 as a cheaper and easier solution is also mentioned. The purpose of the purge is to prevent condensation in certain cold weather conditions, as it could affect the quality of the display. The use of nitrogen is suggested as a common solution to disp
  • #1
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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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  • #2
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.
 
  • #3
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.
 
  • #4
You could always do the assembly in a low humidity room (environmentally controlled, RH & Temp, walk-in chamber).
 
  • #5


I would recommend carefully considering the properties of each gas before making a decision. While R134a and argon are both heavy gases, they have different chemical and physical properties that may affect their performance in this application. Additionally, their potential to absorb moisture should also be taken into consideration.

CO2 may be a cheaper and easier option, but it is also a much lighter gas and may not be as effective in purging the air from the encasement. It is important to balance cost and convenience with the effectiveness of the gas in achieving the desired outcome.

I would also recommend conducting some testing to determine the most suitable gas for this application. This could involve measuring the moisture content of the gases after they have been sitting in the device for a few minutes, as well as testing the effectiveness of each gas in purging the air.

Overall, it is important to carefully evaluate all options and consider the specific requirements and limitations of the project before making a decision on which gas to use.
 

Related to Seleing heavy gas for instrument diplay purge

1. What is "sealing heavy gas" and how does it relate to instrument display purge?

Sealing heavy gas refers to the process of using a dense gas, such as sulfur hexafluoride, to create a barrier between the atmosphere and the internal components of an instrument. This is commonly used in instrument display purge to prevent the intrusion of moisture or other contaminants that could affect the accuracy or functioning of the instrument.

2. Why is it important to use a heavy gas for instrument display purge?

Heavy gases have a higher density than air, meaning they can create a more effective seal and prevent any air or moisture from entering the instrument. This is especially important in sensitive instruments where even small amounts of contamination can impact their performance.

3. How is a heavy gas used in instrument display purge?

The heavy gas is typically released into the instrument through a specific inlet or port, displacing any air or moisture that may be present. The gas then forms a barrier, keeping the internal components of the instrument isolated from the outside environment.

4. Are there any safety concerns with using heavy gas for instrument display purge?

While heavy gases are generally considered safe to use in instrument display purge, it is important to follow proper procedures and precautions to prevent any potential hazards. This may include using proper protective equipment and ensuring proper ventilation in the area where the gas is being used.

5. Can any type of heavy gas be used for instrument display purge?

No, not all heavy gases are suitable for instrument display purge. The gas must have a high enough density to effectively seal the instrument, but also be compatible with the materials used in the instrument and not cause any damage. Some common heavy gases used for instrument display purge include sulfur hexafluoride, argon, and krypton.

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