FAQ - Turbo pump versus Diffusion pump
Posted: Wed Oct 17, 2012 10:46 am
This will be a FAQ designed to just give a bare outline about these two different types of secondary high vacuum pumps that are needed in virtually every successful fusor.
Questions to answer:
1. How much money do you have?
2. How skilled are you at electronics work?
3. Are you just looking to make a fusor and nothing else vacuum related?
We will answer these questions later.
Advantages and Disadvanatges:
A Turbo pump will not foul a chamber with oil if mistakes are made in startup or shut down. A diff pump can foul a fusor chamber if not operated correctly, forcing complete disassembly and cleaning of the fusor and vacuum lines to it.
A turbo pump is expensive if purchased used and warranted to work and if purchased with it required controller and cabling ($450.00 to $1,500). It is incredibly expensive new, ($3,000-$10,000). Factory repairs, if needed, will almost certainly cost more than the entire price spent on a used turbo pump.($500 or more) E-bay bargains on Turbos are often not specified to be working and often include no electronic controller or the special cabling.
A Diff pump is usually rather cheap ($40.00 to $150.00) used and is just not worth purchasing new or even refurbished. The worst repair needed would be for an easily user replacable heating element. ($40.00-$60.00)
A diff pump can stand alone. It is non-electronic in nature and has no mechanical parts or bearings to fail or go bad.
Turbo pumps demand a multiphase electronic controller and cabling. They have a complicated ultra fast rotating blade system and an internal motor and special bearings.
Garbage falling into a diff pump from the main chamber will not harm it nor stop its action.
In a turbopump, the entire item can be completely destroyed in seconds if a tiny fragment of solid material falls into the turbine-like, multi-stage, blade group.
Both pumps may or may not require water cooling depending on you choice at time of purchase. (there are air cooled types of both pumps which the user should look for and demand to keep operations simple and inexpensive.
Answers to questions...................
1. If money is no object then either pump is good, but the turbo might be better
2. If you are not electronically inclined to do limited controller repairs or to build your own controller, if your cheapo e-bay turbo pump has no controller, then the diff pump is a far better choice.
3. If the fusor is your only quest and you will not continue with vacuum related work in future then the diffusion pump is your pump. No need to spend big money on a deep pumping oil free system if you are not going to need that capability in future.
4. If you choose to go turbo, check out the FAQ on tips for mounting and use found here....
viewtopic.php?t=14636
Finally, in real life, most would-be fusioneer folks opt for an air cooled diffusion pump due to price, simplicity, ease of repair and maintenance, etc. Serious researchers and "vacuum-head" purists planning to go into other vacuum related research usually choose the turbo pump. Superlative "mega-neutron" fusors have been successfully operated using both types of pumps.
Search other FAQs for more info on the selection, care, feeding and operation of the diff pump.
******************* 2021 expansion on things related to the usually encountered turbo pump body only for sale **********
Turbos without controller and cabling being offered for sale should be looked at with a juandiced eye. This is the same for any used pump, be it mechanical, diffusion, or turbo. So many of these offerings are just dead. Without some complete guarantee of full functionality, your money is probably ill spent. Turbo's are particularly a "pig in a poke".
A mechanical pump can be tested relatively easily and quickly for a refund if shot. Diff pumps only need and ohmeter to make sure the heater is good and an optical inspection to make sure it is clean and has all of the stack there and that it is intact.
A turbo without cables and a controller cannot be tested at all until you either purchase a controller and cables or assemble and hand construct a controller and make up a cable. Try and get a refund 6 months to a year down the road when you finally spin it up and discover the bearings are shot. A working turbo pump is a complete, complex system and not just a pump body.
In the vast majority of turbo pump offerings, the owner found it surplus for $2.00 in a junk pile, looks the price of his model up and sees that these things, when new, sell for thousands! He then puts it out for sale at $200. Most likely, the person knows nothing about vacuum systems, etc., much less the history of the pump.
Richard Hull
Questions to answer:
1. How much money do you have?
2. How skilled are you at electronics work?
3. Are you just looking to make a fusor and nothing else vacuum related?
We will answer these questions later.
Advantages and Disadvanatges:
A Turbo pump will not foul a chamber with oil if mistakes are made in startup or shut down. A diff pump can foul a fusor chamber if not operated correctly, forcing complete disassembly and cleaning of the fusor and vacuum lines to it.
A turbo pump is expensive if purchased used and warranted to work and if purchased with it required controller and cabling ($450.00 to $1,500). It is incredibly expensive new, ($3,000-$10,000). Factory repairs, if needed, will almost certainly cost more than the entire price spent on a used turbo pump.($500 or more) E-bay bargains on Turbos are often not specified to be working and often include no electronic controller or the special cabling.
A Diff pump is usually rather cheap ($40.00 to $150.00) used and is just not worth purchasing new or even refurbished. The worst repair needed would be for an easily user replacable heating element. ($40.00-$60.00)
A diff pump can stand alone. It is non-electronic in nature and has no mechanical parts or bearings to fail or go bad.
Turbo pumps demand a multiphase electronic controller and cabling. They have a complicated ultra fast rotating blade system and an internal motor and special bearings.
Garbage falling into a diff pump from the main chamber will not harm it nor stop its action.
In a turbopump, the entire item can be completely destroyed in seconds if a tiny fragment of solid material falls into the turbine-like, multi-stage, blade group.
Both pumps may or may not require water cooling depending on you choice at time of purchase. (there are air cooled types of both pumps which the user should look for and demand to keep operations simple and inexpensive.
Answers to questions...................
1. If money is no object then either pump is good, but the turbo might be better
2. If you are not electronically inclined to do limited controller repairs or to build your own controller, if your cheapo e-bay turbo pump has no controller, then the diff pump is a far better choice.
3. If the fusor is your only quest and you will not continue with vacuum related work in future then the diffusion pump is your pump. No need to spend big money on a deep pumping oil free system if you are not going to need that capability in future.
4. If you choose to go turbo, check out the FAQ on tips for mounting and use found here....
viewtopic.php?t=14636
Finally, in real life, most would-be fusioneer folks opt for an air cooled diffusion pump due to price, simplicity, ease of repair and maintenance, etc. Serious researchers and "vacuum-head" purists planning to go into other vacuum related research usually choose the turbo pump. Superlative "mega-neutron" fusors have been successfully operated using both types of pumps.
Search other FAQs for more info on the selection, care, feeding and operation of the diff pump.
******************* 2021 expansion on things related to the usually encountered turbo pump body only for sale **********
Turbos without controller and cabling being offered for sale should be looked at with a juandiced eye. This is the same for any used pump, be it mechanical, diffusion, or turbo. So many of these offerings are just dead. Without some complete guarantee of full functionality, your money is probably ill spent. Turbo's are particularly a "pig in a poke".
A mechanical pump can be tested relatively easily and quickly for a refund if shot. Diff pumps only need and ohmeter to make sure the heater is good and an optical inspection to make sure it is clean and has all of the stack there and that it is intact.
A turbo without cables and a controller cannot be tested at all until you either purchase a controller and cables or assemble and hand construct a controller and make up a cable. Try and get a refund 6 months to a year down the road when you finally spin it up and discover the bearings are shot. A working turbo pump is a complete, complex system and not just a pump body.
In the vast majority of turbo pump offerings, the owner found it surplus for $2.00 in a junk pile, looks the price of his model up and sees that these things, when new, sell for thousands! He then puts it out for sale at $200. Most likely, the person knows nothing about vacuum systems, etc., much less the history of the pump.
Richard Hull