As with any lab, there are problems. Many many problems. For project 2, described in my previous post (Week 1 Post 2). The objective was to take the underground gas, pass it through the Zeolite filled tank, and fill a small chamber with the filtered gas.
Zeolite is a type of molecular sieve which traps mostly Argon and Nitrogen molecules and allows other gases to pass through it. It just looks like a bunch of small beads, for more information: http://en.wikipedia.org/wiki/Zeolite. In this case, in order to increase the concentration of the Helium in the underground gas sample we wanted to remove as much of the other gases in the underground gas so it would be easier for the scientists in Harvard to analyse the Helium.
So the process began; we cut our own copper wire, attached our own fittings, fit our valves, tied strings to support the plumbing, and used nothing more than wrenches. Of course, we did not want to contaminate any part of the copper tubing or fittings so we had to carefully think about how we would go through with the plumbing. Unfortunately, (you'll see why it is unfortunate later) a part of the plumbing had been started earlier by Geoffrey and Dr. Calaprice. We added on to this hoping it would make the process faster.
So we completed the plumbing for the underground gas to pass through the Zeolite bottle, trigger a pressure gauge, then enter the small chamber which we would send off to Harvard. However, in order to increase the purity of the system we wanted to purge the whole system with a gas previous to allowing our precious underground pass through it. So originally we decided to purge the whole system with Argon gas. The idea was to use an inert gas to purge the Zeolite bottle and copper tubing via pushing all the other unwanted gases out of the system. Then after purging it we would have to pump down to pull all of the argon out of the system so we could pass the underground gas.
The Zeolite bottle was pretty large, probably like a 20-30 liter bottle. When we purged the whole system we passed Argon through the Zeolite and then vented it out to air to let it out. We knew that Argon would become trapped in the Zeolite and we hoped we could saturate the Zeolite and then push out everything else. What we didn't realize was how hard it would be to pump down the whole system with so much Argon trapped in the Zeolite. The turbo pump wasn't even able to reach its maximum RPM without overloading with power because it was having such a hard time pumping out the Argon from the tubing and Zeolite. We realized that the sheer amount of Zeolite made it very hard to pump down all of the Argon trapped in it.
Further, because we had added onto plumbing that was already there, the system became very large and relatively complex. It becomes much harder to pump down a large bottle when there is so much copper tubing it has to pass through before being pumped out. We spoke to the lab technician Allen who suggested we connect the Turbo pump much closer to the Zeolite bottle so that it wouldn't have to pump it down through so much copper wire. We disconnected a valve close to the Zeolite bottle and connected the Turbo pump there. Although the Turbo pump was eventually able to pump down the enormous pressure inside of the Zeolite bottle it took almost 2 days to get this done.
Normally, atmospheric Helium is used to purge the Zeolite bottle, however we avoided using it because we didn't want atmospheric Helium to contaminate the underground gas sample. This is because Helium does not get trapped in the Zeolite and it is a very light gas making it fairly easy to pump down on. Since Argon was such a hassle, we decided to use Helium despite this.
In order to make sure we were actually pushing air out we connected a capillary to the tubing which lead back to a Residual Gas Analyzer (RGA) which is a mass spectrometer for gasses. Eventually we saw that after passing the Helium through the Zeolite bottle the Argon level drastically dropped suggesting that all the Argon trapped in the Zeolite was now mostly gone. Eventually through much trial and tribulation we were able to purge the system with Helium and then pump it down.
As I said before, the purging and pumping was done with the Turbo Pump connected close to the Zeolite bottle, however in order for us to pass the underground gas through the Zeolite bottle and into the small chamber we had to resort to the more complex tubing. So we reconnected all the tubing and leak checked it which took a full day on its own because we found that there were many many problems with the tubing and fittings. Punctured copper wire is never a good thing.
We were finally ready, so we pumped the whole system down and used a pressure gauge to fill the small chamber with 20psi of Zeolite filtered underground gas (which was 99.9% Helium after passing through the Zeolite). It was relieving to finally finish a project that should have taken us 4-5 days but instead took almost 2 weeks. On Monday we will figure out how to ship it to Harvard.
In the meantime we had received a new sample of underground gas from a well in New Mexico which we will hopefully analyze with the RGA next week. Dr. Calaprice also outlined a new project for us which I will describe in the next post.
Zeolite is a type of molecular sieve which traps mostly Argon and Nitrogen molecules and allows other gases to pass through it. It just looks like a bunch of small beads, for more information: http://en.wikipedia.org/wiki/Zeolite. In this case, in order to increase the concentration of the Helium in the underground gas sample we wanted to remove as much of the other gases in the underground gas so it would be easier for the scientists in Harvard to analyse the Helium.
So the process began; we cut our own copper wire, attached our own fittings, fit our valves, tied strings to support the plumbing, and used nothing more than wrenches. Of course, we did not want to contaminate any part of the copper tubing or fittings so we had to carefully think about how we would go through with the plumbing. Unfortunately, (you'll see why it is unfortunate later) a part of the plumbing had been started earlier by Geoffrey and Dr. Calaprice. We added on to this hoping it would make the process faster.
So we completed the plumbing for the underground gas to pass through the Zeolite bottle, trigger a pressure gauge, then enter the small chamber which we would send off to Harvard. However, in order to increase the purity of the system we wanted to purge the whole system with a gas previous to allowing our precious underground pass through it. So originally we decided to purge the whole system with Argon gas. The idea was to use an inert gas to purge the Zeolite bottle and copper tubing via pushing all the other unwanted gases out of the system. Then after purging it we would have to pump down to pull all of the argon out of the system so we could pass the underground gas.
The Zeolite bottle was pretty large, probably like a 20-30 liter bottle. When we purged the whole system we passed Argon through the Zeolite and then vented it out to air to let it out. We knew that Argon would become trapped in the Zeolite and we hoped we could saturate the Zeolite and then push out everything else. What we didn't realize was how hard it would be to pump down the whole system with so much Argon trapped in the Zeolite. The turbo pump wasn't even able to reach its maximum RPM without overloading with power because it was having such a hard time pumping out the Argon from the tubing and Zeolite. We realized that the sheer amount of Zeolite made it very hard to pump down all of the Argon trapped in it.
Further, because we had added onto plumbing that was already there, the system became very large and relatively complex. It becomes much harder to pump down a large bottle when there is so much copper tubing it has to pass through before being pumped out. We spoke to the lab technician Allen who suggested we connect the Turbo pump much closer to the Zeolite bottle so that it wouldn't have to pump it down through so much copper wire. We disconnected a valve close to the Zeolite bottle and connected the Turbo pump there. Although the Turbo pump was eventually able to pump down the enormous pressure inside of the Zeolite bottle it took almost 2 days to get this done.
Normally, atmospheric Helium is used to purge the Zeolite bottle, however we avoided using it because we didn't want atmospheric Helium to contaminate the underground gas sample. This is because Helium does not get trapped in the Zeolite and it is a very light gas making it fairly easy to pump down on. Since Argon was such a hassle, we decided to use Helium despite this.
In order to make sure we were actually pushing air out we connected a capillary to the tubing which lead back to a Residual Gas Analyzer (RGA) which is a mass spectrometer for gasses. Eventually we saw that after passing the Helium through the Zeolite bottle the Argon level drastically dropped suggesting that all the Argon trapped in the Zeolite was now mostly gone. Eventually through much trial and tribulation we were able to purge the system with Helium and then pump it down.
As I said before, the purging and pumping was done with the Turbo Pump connected close to the Zeolite bottle, however in order for us to pass the underground gas through the Zeolite bottle and into the small chamber we had to resort to the more complex tubing. So we reconnected all the tubing and leak checked it which took a full day on its own because we found that there were many many problems with the tubing and fittings. Punctured copper wire is never a good thing.
We were finally ready, so we pumped the whole system down and used a pressure gauge to fill the small chamber with 20psi of Zeolite filtered underground gas (which was 99.9% Helium after passing through the Zeolite). It was relieving to finally finish a project that should have taken us 4-5 days but instead took almost 2 weeks. On Monday we will figure out how to ship it to Harvard.
In the meantime we had received a new sample of underground gas from a well in New Mexico which we will hopefully analyze with the RGA next week. Dr. Calaprice also outlined a new project for us which I will describe in the next post.
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