Homemade vacuum easel-Beware!

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From: John Cremati (johnjohnc@core.com)
Date: 02/10/03-04:08:58 AM Z


      I would just like to caution anyone thinking of buying a used vacuum
pump.. I own 6 vacuum pumps with the last one I purchased on E-Bay which
I would never do again even though I got a really good pump.. You need to
check them out thoroughly before you buy one......
       Vacuum oil traps moisture and routine maintenance is often neglected
if done at all.. . Many industrial or scientific systems have a cold trap to
prevent this moisture from contaminating the oil... But these systems are
very expensive and large and are still generally very neglected...........
      Also in many chemical applications that use a vacuum , the chemicals
seriously deteriate the pump... The oil that is in the pump may be
extremely toxic when you get it depending on the chemicals they were using.
You never know !..
      Repairing vacuum pumps can be very pricey with just a new set of
seals selling for over $100 plus labor and if the Oil has sludged so badly
the pump may have to be completely overhauled which can cost $500 to $1000
even on a small pump....
    I would recommend sticking with a Name brand such as Leibold or Seargent
Welsh for parts availability.... You can find used pumps everywhere thru
surplus, salvage or used machinery dealers, industrial auctions, ect... .
New precision pumps cost several thousand dollars and used they generally
cost just a few hundred...
    Most Pumps will mist oil in the exhaust so you need a really good
filter for the exhaust portion of the pump... To get away cheap , I put a
coalescing filter on one of mine that is used for compressed air... You may
even want to mount the pump in a remote location from a photographic area. I
piped several of mine in PVC and although not precision it will handle
the vacuum .. I would also recommend a filter on the intake to prevent any
dirt from entering the pump...
     Change the oil frequently as it does not take much moisture to
contaminate the oil..
     A oiless pump or roots blower might be a good way to go on a vacuum
easel system but they will generally not pull the amount of vacuum of a
rotary vein oil type pump... I have a 1 horsepower Seargent Welsh that I
use to pull down a 7 foot x 4 foot vacuum frame, it is a cranker but the
oil mist is extremely bad so I guess there is a trade off ..... Some pumps
have better oil return systems in them than others and will not mist as
bad..The last one I bought called "Galileo" which a off name brand but does
not seem to mist hardly at all...
 My 2 bits worth....
Regards ,
John Cremati


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