Shutting down turbo and fusor valve

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David Kunkle
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Shutting down turbo and fusor valve

Post by David Kunkle »

Hi all,

After reading through all the vacuum FAQs, let me see if I have this right...

For a turbo, what it amounts to is it has to be under vacuum already to a) turn it on... and b) shut it off in order to not damage it?

Partly theoretical here referring to "FAQ - Operating a Fusor - startup - run - shutdown" -Under shutdown #4. If the turbo is running and the fusor is under full vacuum w/ gas feed shut off, is there any reason why the turbo can't be switched off without closing the fusor gate valve? I understand the valve is needed to throttle the pump when D is being flowed through the fusor- but other than that, is there any absolute need for it?

Thanks.
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Dennis P Brown
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Re: Shutting down turbo and fusor valve

Post by Dennis P Brown »

A turbo needs to be under vacuum (say below half a torr or 500 microns before it is started (but this is an arbitrary value but a safe value.) That means a turbo MUST have a fore line vacuum system (just like a diffusion pump.) Since getting a two stage pump is the best choice, often people have these high performance pumps with turbo's but that level of vacuum is not required. However, a good pumping speed (greater than the turbo) must be available so the fore line pressure remains low. The lower the fore line pressure, often the lower the turbo can pump a system. Some turbo's have a side vent which allows atmospheric pressure to be admitted once the unit is powered off (critical) and needs to be stopped.

As for your second question - yes, a turbo can be turned off if the system is idle/gate valve open but why? If the system is operational but not being used as a fusor for a while, than the turbo needs to run to keep out gassing in check. If the system is to be shut down, best to close the gate valve and keep the fusor section under vacuum to keep it clean. Some people feel (mfg say this) that it is best to use the side vent (IF so equipped) to vent the turbo to stop its rotation quickly through the bad harmonic section most have. Some people do not like doing this and let them spin down on their own - especially if one does not use dry air since moisture will make pumping a fusor down again more difficult. Also, some turbo's do not have this vent (or so I think.)

As for the fore pump, a good two stage can be used for a lot of things, so having one with the turbo is just a good idea but not required; as long as the pump can keep the turbo fore line low enough for safe operation than that pump is good enough even if it isn't a two stage. Considering two stage pumps can be obtained rather cheap on e-bay if you are careful, it might be best to get one regardless of your needs.
David Kunkle
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Re: Shutting down turbo and fusor valve

Post by David Kunkle »

That all makes perfect sense now. Thanks for the info.

One other question now that I'm looking more seriously at turbos:

I get that you need a controller and cable to connect to the turbo. Where does the controller plug in to an outlet? Another cable no one ever talks about in the ads? I just saw one that has an integrated controller with the turbo, but apparently also needs a power supply that plugs into the controller.
If your experiment needs statistics, you ought to have done a better experiment.

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Dennis P Brown
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Re: Shutting down turbo and fusor valve

Post by Dennis P Brown »

Like 99.9% of all scientific equipment sold for 110 v operation (remember, some big turbo's may use 220 v and require a "hard wiring" setup), the turbo controller will have a standard wall outlet access port for a removable plug that fits a std plug. Those cords are universal. While anything is possible, I've never seen a controller that requires a separate power supply.

I strongly suggest that you be careful building a real fusor by reading and fully understanding the electrical power requirements for safe design and more to the point, operation of the extremely dangerous high voltage/current systems used by these devices - the electrical dangers are great and your inexperience with power systems indicates that is an area you need to be extra careful about. Maybe consider a demo fusor power supply - a neon sign transformer (NST) based system. These require less electrical experience to construct. They are not toys and can be dangerous but are far safer compared to the HV supply of a real fusor.

Best of luck on the hunt for a turbo system.
David Kunkle
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Re: Shutting down turbo and fusor valve

Post by David Kunkle »

Thanks for the info. Turbos are definitely new to me. I guess in every single "for sale" photo I've seen, I've never seen a shot of the plug in for a standard cord.

Thanks again.
If your experiment needs statistics, you ought to have done a better experiment.

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Richard Hull
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Re: Shutting down turbo and fusor valve

Post by Richard Hull »

You never will see a standard plug on a turbo pump. They are deliberately designed to warrant a captive audience by the manufacturer so they can sell their highly marked up cabling with special plugs to and from the custom controller. Admittedly, many of the plugs are indeed standard within the industry of ultra high cost electronics goods. It is just that the average joe will never see those standards and will be forced to seek out special jobbers to get the proper plugs and pay big bucks for each plug, even if he hand wires his own cables! Canon and AMP are big odd plug manufacturers with hundreds of varieties of oddball plugs.

When it comes to high end scientic hardware there are few standards between manufacturers.

Richard Hull
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Jerry Biehler
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Re: Shutting down turbo and fusor valve

Post by Jerry Biehler »

Not true. The turbovac 50 pumps from leybold use a very generic 4 connector plug that is all over and used on pneumatic and hydraulic valves, they are about $5 to $10. On the NT12 and 13 drive for those pumps they use a standard DIN connector that is about 15 to 25 from mouser. Early NT10 and NT50 drives had a euro make connector and they were replaced with more generic Phoenix brand connectors in later units. Most larger leybold drives use AMP cpc connectors (Which are great, cheap and durable, I used them very often)

Pfeiffer and others pretty generic amphenol or cannon connectors on the pumps.

Even the giant 2000l/s mag lev pump I have has pretty generic connectors on it, cannon plugs on one side and japanese honda plugs on the other side.

Amphenol has a very good chart to figure out which pin configuration and shell size you have, once you have that pop over to ebay with the part number and you will usually find a seller with them for 1/10th price new.

If you want odd ball connectors, one of my little thermal infrared cameras use a special 12 pin connector that is only available from one company. Darn thing cost me $95. Ouch.
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