Replacing vacuum pump on investing table

Jewelry Discussion
1

I need to replace the vacuum pump on my investing table. All I know
is it is a 1/2 hp motor. no other specs. What are the normal specs
for a replacement? Where can I get on? Will an refrigerant or hvac
vacuum pump like JB or Robinair work?

2

A vaccum pump of capacity of 100 liters per minutes or 1.5 CFM is
required for investing table which is small.

If you are buying a new one go for 100 liters per minutes minimum
and not 60 liters per minutes because the price differece is not
much.

I have a double rotaty vane vaccum pump of 300 liters per minutes
capacity, I have a vaccum tank of 12 inches diameter by nine inches
height.

The higher the capacity the faster the air removal and total air
removal from the investment slurry.

Hope this will help.
Best of Luck

May God bless us all with total health (Mental, Physical, spiritual
and social)

Strive to be Happy
Umesh

3 
If you are buying a new one go for 100 liters per minutes minimum
and not 60 liters per minutes because the price differece is not
much. I have a double rotaty vane vaccum pump of 300 liters per
minutes capacity, I have a vaccum tank of 12 inches diameter by
nine inches height.

Umesh your conversions are a little off 1.5 cu ft is 42.47 liters (1
cu ft= 28.3168466 liters) so your 100 liter per min pump is a 3.53
cfm (cu ft per minute) pump. And for a small bell jar you might find
3 cfm ok, I would suggest at least 5 cfm minimum size for the speed
of pump down needed to get good bubble removal.

Jim

James Binnion
@James_Binnion
James Binnion Metal Arts

360-756-6550

4

Another important factor to consider is that the inside diameter of
the lines you use to hook up your system, they will also be a
limiting factor on the capaity of the vacum pump. I would reccomend
at least 3/8 copper tubing with a pigtail (full 360 degree loop).
Hoses can pinch down internally even if rated for vacum use. The
accumulator (vacum tank) can function well to keep debris out of the
pump inself. Moisture will probably find it’s way into the pump oil
with your usage. I suspect frequent oil changes and use of the gas
ballast would be a good idea. An alternative would be to have the
accumulator kept cold to force the moiture to condense there and
trap out. I don’t do casting but have used a vacum pump extensively
for 20+ years and my advice is based upon that usage in dehydrating
refrigeration systems. Hope this helps.

Dan Wellman