Fusion Message Board

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, 6:17 pm
Poster: Richard Hester

On Aug 31, 6:17 pm, Richard Hester 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.

.....A long rundown from Mr. Hull on the care and feeding of traps follows - thanks.....

A lot of this is also available on the web from Lesker and other folks who sell the traps, as I found out when I tried to get more info (try sisweb.com). The trap I have is from Metra, Inc. in Maryland, and is 4 1/2"in diameter and
7 7/8" long, with KF40 fittings on both sides.It should eat a lot of water vapor.
I have been finding that at least in my locale(Silicon Valley), pneumatically operated high vacuum valves are a lot more easily available as surplus and vastly cheaper than refurbished manual valves from folks like Lesker and Duniway, enough so that it might well be worthwhile to set up a small compressor just to actuate the valves. This is probably due to the heavy investment in vacuum facilities by all the semi companies in the area. I picked up a brand new (caps and foil seals still on the flanges) Nor-Cal valve with KF25 right angle in/out for a little over $40, and am waiting for a couple more likely specimens to keep it company.

As I go about trying to locate all these odds and ends, I find myself muttering a little mantra - "vacuum costs money, vacuum costs money...."