In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.
Subject: Re: Trap vs. Trap
Date: Aug 31, 10:04 am
Poster: Richard Hull
On Aug 31, 10:04 am, Richard Hull wrote:
>I just picked up a rather large molecular sieve foreline trap for next to nothing, and wondered about its effectivness compared to the molecular maze trap from Lesker that Richard Hull talked about a month or two ago? Anyone had experience with both?
> Richard Hester
I have both types of trap. I naturally prefer the micro-maze, but the zeolite trap is fine provided you maintain it well. The micro maze will let you go a little lower and stops some species not trapped by the common zeolite trap.
The key is the cost of the valves to even use a trap!!!! You will need 2 valves minimum......... a valve immediately on each side of your trap.
This is to prevent contamination of your chamber during bakeout.
To use, put in fresh zeolite. Start up with all valves closed.
1. Start the pump
2. Open the valve on the pump side of the trap.
3. Turn on trap heater
4. Walk away for 5 hours
5. Return and turn off heater
6. Walk away until trap is cool to the touch
7. Open valve on the fusor chamber side of trap.
8. The thing will pump down like a bandit!
9. Run fusor in glow mode to get to the bottom pressure.
10.Close valve on pump side of trap.
11.Turn off pump.
12.Run fusor normally by admitting D2 gas to ~5 microns
13.When done, close the fusor side valve.
14.Make doubly sure all valves are closed.
15.You may now open or "vent" the pump line to air to avoid oil wicking up hose line.
Never, ever allow air into the trap again!!!!!! Until, of course, you need to replace the zeolite (yearly)
Bakeouts are accomplished as above whenever the bottom pressure starts to drift upwards. Sometimes as often as every four fusor runs.
If not baking out, but just running fusor, then...
1. Start pump to evacuate the foreline.
2. Gas ballast the pump well
3. Run for 2 minutes minimum
4. Open pump side valve on trap
5. Pump two minutes more
6. Now you may open the chamber side valve.
Remember, the pump valve is the first to be opened and last to be shut. The fusor side valve is the last to be opened and the first to be shut.
Isolate the chamber first and the trap second. Protect all from the air at all times!!!
A carelessly run trap can actually foul and ruin a fusor chamber with crap not easily removed.
- Re: Trap vs. Trap - Richard Hester Aug 31, 6:17 pm