Liquid nitrogen transfer into nitrogen purged enclosure

In summary, this person is trying to build a system to transfer liquid nitrogen (LN) into a roughly 6'x4'x2' sealed nitrogen gas-purged enclosure. The LN is in a pitcher-style dewar like this http://static.coleparmer.com/large_images/03773_51.jpg but with an open top, and the container I'd like to transfer it into inside the enclosure will also be open-topped. The enclosure has several threaded holes (1-1/4 NPT) at the top I can use for my transfer apparatus, has a relief valve for overpressure, and is under a continuous flow of nitrogen gas on the order of 30
  • #1
abedmcnulty
1
0
I am trying to build a system to transfer liquid nitrogen (LN) into a roughly 6'x4'x2' sealed nitrogen gas-purged enclosure. The LN is in a pitcher-style dewar like this http://static.coleparmer.com/large_images/03773_51.jpg but with an open top, and the container I'd like to transfer it into inside the enclosure will also be open-topped. The enclosure has several threaded holes (1-1/4 NPT) at the top I can use for my transfer apparatus, has a relief valve for overpressure, and is under a continuous flow of nitrogen gas on the order of 30 SCFH.

Ideally I'd like to do this as simply as possible, something like pouring the LN slowly into a funnel leading into a wide tube, which will allow the excess nitrogen gas generated by the LN boiling off to flow up the tube and into the room. I know I need some kind of valve at the wall of the enclosure, preferably something that will just open under the weight of the LN, without allowing oxygen into the enclosure, which should be maintained at ppm levels of O2. Any thoughts on what kind of valve I can use to do this, or if this plan is even feasible? Thanks!
 
Engineering news on Phys.org
  • #2
I would consider a flap valve, hinged on a single pin, with a counterweight to keep it closed.
Construction from stainless steel sheet.
LN2 poured down the tube would pass this valve, then it would swing back up to close the pipe.
The fit does not need to be good since venting N2 will flush the tube.

Take a look at the flap valve at the top of truck's diesel engine exhaust stack.
You need an inverted one of those. Come to think of it, they are available in stainless.
Re-purpose one by inverting it and increasing the counter weight.
 
  • #3
Do you even need a valve given that the N2 will be boiling off at a fair clip and the pipe is pretty narrow?
This is a pretty sizeable volume (almost 50 cubic feet) of N2 and at room temperature, even a pretty decent dewar will have steady venting.
 

1. What is the purpose of transferring liquid nitrogen into a nitrogen purged enclosure?

Liquid nitrogen is used as a cryogenic coolant in many scientific experiments and processes. Transferring it into a nitrogen purged enclosure helps to minimize the risk of exposure to oxygen and moisture, which can affect the properties of the liquid nitrogen and potentially compromise the experiment or process.

2. How is the transfer of liquid nitrogen into a nitrogen purged enclosure performed?

The transfer is typically done using a specialized container or dewar flask designed for handling and storing liquid nitrogen. The container is connected to the purged enclosure using a transfer line and the liquid nitrogen is carefully poured or pumped into the enclosure.

3. What precautions should be taken when transferring liquid nitrogen into a nitrogen purged enclosure?

It is important to wear appropriate personal protective equipment, such as gloves and safety glasses, when handling liquid nitrogen. The transfer should also be done in a well-ventilated area to prevent the buildup of potentially hazardous levels of nitrogen gas. Additionally, the transfer should be done slowly and carefully to avoid spills or splashes.

4. What are the benefits of using a nitrogen purged enclosure for handling liquid nitrogen?

Using a nitrogen purged enclosure helps to maintain the purity and stability of the liquid nitrogen, ensuring that it remains at the desired temperature and does not become contaminated by oxygen or moisture. This can improve the accuracy and reliability of experiments and processes that require precise temperature control.

5. Are there any potential risks associated with transferring liquid nitrogen into a nitrogen purged enclosure?

While the transfer process itself is relatively safe when proper precautions are taken, there are some potential risks to be aware of. These include the risk of asphyxiation due to the displacement of oxygen by nitrogen gas, as well as the risk of frostbite or burns from direct contact with the extremely cold liquid nitrogen. It is important to follow safety protocols and receive proper training before handling liquid nitrogen.

Similar threads

  • General Engineering
Replies
10
Views
2K
  • Mechanical Engineering
Replies
3
Views
895
Replies
8
Views
5K
Replies
16
Views
4K
Replies
14
Views
2K
Replies
7
Views
3K
  • Advanced Physics Homework Help
Replies
2
Views
6K
Replies
89
Views
34K
Back
Top