On Fri, 27 Jan 2006 17:30:16 GMT, Ignoramus13653
wrote:

I won a Sun "refrigerant recovery unit" in a military auction for
$55. I have not picked it up yet, but it looks to have been used very
lightly, if at all (I'll see, it is rated A4). As I learned after I
won it, it is for "old style R12" systems, whatever that is. So it is
not that valuable.

My issue is that I need a vacuum pump. Are vacuum pumps in these
machines any good and can they be ripped out and outfitted with
regular 1/4" NPT fittings.

Thanks

Depends on why you want a vacuum. Such a pump should pull at least
28" of Hg, which is useful for some purposes but not for others.
It's fine for degassing molding materials, not nearly enough vacuum
for sputtering mirrors or metallization.

What would you use it for?

On Fri, 27 Jan 2006 19:51:53 GMT, Ignoramus13653
wrote:

On Fri, 27 Jan 2006 13:45:18 -0600, Don Foreman wrote:
On Fri, 27 Jan 2006 17:30:16 GMT, Ignoramus13653
wrote:

I won a Sun "refrigerant recovery unit" in a military auction for
$55. I have not picked it up yet, but it looks to have been used very
lightly, if at all (I'll see, it is rated A4). As I learned after I
won it, it is for "old style R12" systems, whatever that is. So it is
not that valuable.

My issue is that I need a vacuum pump. Are vacuum pumps in these
machines any good and can they be ripped out and outfitted with
regular 1/4" NPT fittings.

Thanks

Depends on why you want a vacuum. Such a pump should pull at least
28" of Hg, which is useful for some purposes but not for others.
It's fine for degassing molding materials, not nearly enough vacuum
for sputtering mirrors or metallization.

What would you use it for?

My first use would be desoldering. I am not sure about future uses and
whether I would need "deep vacuum". Good question though. In terms of
percentage of air that such pumps remove, would you know how good are
these refrigerant removal pumps?

Thank you

If it pulls 28 in of Hg, and atmospheric pressure is 29.9 in
Hg.......do the math!

It would work fine for desoldering if you have a vacuum reservoir.
The pumps are low volume pumps but a reservoir could provide a pulse
of vacuum when you open a valve. A suitable valve might be the little
pushbutton valve in a cheap blowgun, as:
http://tinyurl.com/cweo9

I've seen these at HF for about $2.

A suitable vacuum reservoir might be an old 16.4 oz propane bottle.

A recovery unit has a lot of extra stuff in it because it has to cool the
compressed refrigerant before it goes into the cylinder. You can probably
strip out the pump but the other parts fall into that permanent junk box
classification of "useless but to valuable to throw away". :-)

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Don Foreman" wrote in message
...
On Fri, 27 Jan 2006 17:30:16 GMT, Ignoramus13653
wrote:

I won a Sun "refrigerant recovery unit" in a military auction for
$55. I have not picked it up yet, but it looks to have been used very
lightly, if at all (I'll see, it is rated A4). As I learned after I
won it, it is for "old style R12" systems, whatever that is. So it is
not that valuable.

My issue is that I need a vacuum pump. Are vacuum pumps in these
machines any good and can they be ripped out and outfitted with
regular 1/4" NPT fittings.

Thanks

Depends on why you want a vacuum. Such a pump should pull at least
28" of Hg, which is useful for some purposes but not for others.
It's fine for degassing molding materials, not nearly enough vacuum
for sputtering mirrors or metallization.

What would you use it for?

Glenn Ashmore wrote:
A recovery unit has a lot of extra stuff in it because it has to cool the
compressed refrigerant before it goes into the cylinder. You can probably
strip out the pump but the other parts fall into that permanent junk box
classification of "useless but to valuable to throw away". :-)

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.


I have a medical vacuum pump.
Would it be suitable for A/C system evacuation?
Any idea if medical pumps have to meet a lesser spec in terms of in/Hg?

"Ignoramus13653" wrote in message
...
On Fri, 27 Jan 2006 16:04:13 -0500, Glenn Ashmore
wrote:
A recovery unit has a lot of extra stuff in it because it has to cool the
compressed refrigerant before it goes into the cylinder. You can
probably
strip out the pump but the other parts fall into that permanent junk box
classification of "useless but to valuable to throw away". :-)

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.

Milli-torr is certainly very encouraging.

I think that if I cannot sell the unit for much more than a comparable
pump is worth, I would just disassemble the unit and keep the pump.

Thanks Glenn.

i

I wonder if some people responding are confused with the type of "pump" you
have.
I do HVAC work and we have three or four recovery pumps around. None of them
will pump much more than 10" of HG. We have several vacuum pumps to "vac"
the system down when doing repairs that will do much lower vacuum, down in
the 100-200 micron range. Recovery pumps are painfully slow at pulling a
vacuum, their job is to remove refrigerant.
Depending on what you plan on doing with it, it may be enough, or not!
Greg

According to Rex B "":

Glenn Ashmore wrote:

[ ... ]

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.


I have a medical vacuum pump.
Would it be suitable for A/C system evacuation?

I strongly doubt that. Medical vacuum pumps are used for
removing fluids pooling in a area of surgery -- kind of like the pump
put in your mouth at the dentist's. Medium flow, not particularly
strong vacuum.

Strong vacuum would be likely to damage tissue if the tissue
gets pulled against the intake.

Of course -- there could be other uses of vacuum in medical
technology which could require high vacuums -- but I don't know what
they might be.

Any idea if medical pumps have to meet a lesser spec in terms of in/Hg?

I strongly suspect so.

The pumps used for A/C service are about the grade of the oil
wetted pumps used as "fore-pumps" in high vacuum systems. They get the
pressures down to a level where other technologies can take over --
turbo pumps, molecular sieve, oil-diffusion, and various others which
can't even be *started* near atmospheric pressure. And those fore pumps
need to run for quite a while to get even a fairly small vacuum chamber
down to the pressure levels where the other technologies start out.

And the oil wetted pumps are really *too* good for something
like desoldering. For that, I would suggest something like the Gast
brand rotary graphite vane pumps. The oil wetted should be run for a
long time after the majority of the air is pumped out -- in part to
remove gases which have been taken up into the oil during the first part
of the pumping. As they start, you hear a sound sequence like:

Glurk Glurk glurk Poketta Poketta poketta poketta ... tick tick
tick "murmur" ....

with the "Glurk"s being large bubbles of air being passed through the
oil bath, the "poketta"s being much smaller bubbles, the "tick"s even
smaller bubbles, and the "murmur"s being the continuing motion with
nothing measurable really being pumped.

The first few moments -- for however long the "Glurk"s continue,
the exhaust side will carry some oil vapor with it. A lab pump usually
has a trap on the exhaust to condense that oil and drip it back into the
main pump. Sometimes, the exhaust is pumped to the outdoors, instead.

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Ignoramus13653 wrote:
I think that if I cannot sell the unit for much more than a comparable
pump is worth, I would just disassemble the unit and keep the pump.

For what you want it for, desoldering, and maybe some future vacuum
clamping, it should work for you but with one, in my opinon hassle.
Some vac pumps made specifically for pulling down A/C systems are
piston driven and have a lubricant in their crankcase. Some, actually
allow the Freon to go thru the crankcase not much unlike a two stroke
engine. This is the case with your rotary automobile pumps and
Refrigerator pumps.

What this might mean for you is oil mist in the exhaust side of your
pump, and you need to catch it. If it is USED to lubricate the pump,
you need to replace the lost oil somehow. Additionally, that oil mist
is not beneficial in certain shops (like a body shop).

For what you want, and if this one does not work out, watch ebay for a
Gast or Thomas oiless rotary vane pump like this:
http://cgi.ebay.com/1-3-HP-Gast-Vacu... QcmdZViewItem

These will run clean and relatively quiet, pull 26 to 28 inches, often
plenty for clamping with a good seal. They can be put on a tank as long
as you put a checkvalve in it so it does not run backwards when you
shut it down.

Even though these are always rated as continuous duty, you can throw a
swtich in line to cycle it on and off once the tank is full.

If your going to desolder, be sure to locate a tank or cleanable vessel
between you or the pump... the solder has to go somewhere !

Grummy

Wonderful sound reproduction, Don!
Some of my favorite sounds. Used to run a vacuum heat treating
department in the 60's. Had forepumps that could get an 80+ cubic foot
vessel down to 100 microns in a couple of minutes. We could fire up
the diffusion pumps when we hit the switch for the forepump and the oil
wouldn't get hot enough to backstream before we got in range.

Pete Stanaitis
----------------------------


Glurk Glurk glurk Poketta Poketta poketta poketta ... tick tick
tick "murmur" ....

with the "Glurk"s being large bubbles of air being passed through the
oil bath, the "poketta"s being much smaller bubbles, the "tick"s even
smaller bubbles, and the "murmur"s being the continuing motion with
nothing measurable really being pumped.

The first few moments -- for however long the "Glurk"s continue,
the exhaust side will carry some oil vapor with it. A lab pump usually
has a trap on the exhaust to condense that oil and drip it back into the
main pump. Sometimes, the exhaust is pumped to the outdoors, instead.

Enjoy,
DoN.

According to spaco :


Wonderful sound reproduction, Don!

Thanks. :-)

Some of my favorite sounds. Used to run a vacuum heat treating
department in the 60's. Had forepumps that could get an 80+ cubic foot
vessel down to 100 microns in a couple of minutes. We could fire up
the diffusion pumps when we hit the switch for the forepump and the oil
wouldn't get hot enough to backstream before we got in range.

Now *that* is impressive!

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"Greg O" wrote in message
...

"Ignoramus13653" wrote in message
...
On Fri, 27 Jan 2006 16:04:13 -0500, Glenn Ashmore
wrote:
A recovery unit has a lot of extra stuff in it because it has to cool the
compressed refrigerant before it goes into the cylinder. You can
probably
strip out the pump but the other parts fall into that permanent junk box
classification of "useless but to valuable to throw away". :-)

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.

Milli-torr is certainly very encouraging.

I think that if I cannot sell the unit for much more than a comparable
pump is worth, I would just disassemble the unit and keep the pump.

Thanks Glenn.

i

I wonder if some people responding are confused with the type of "pump" you
have.
I do HVAC work and we have three or four recovery pumps around. None of them
will pump much more than 10" of HG. We have several vacuum pumps to "vac"
the system down when doing repairs that will do much lower vacuum, down in
the 100-200 micron range. Recovery pumps are painfully slow at pulling a
vacuum, their job is to remove refrigerant.
Depending on what you plan on doing with it, it may be enough, or not!
Greg

Thanks for pointing that out. Unless it is a recovery/recharging station I certainly
wouldn't expect that much out of it either. The recovery unit I used years ago for
automotive systems shut the system off at about 17 inches Hg. It also had a scale and a
circulating pump and filter for cleaning the reclaimed refrigerant. It was essentially a
refrigerator compressor with some valving.

On Fri, 27 Jan 2006 22:10:26 GMT, Ignoramus13653
wrote:

On Fri, 27 Jan 2006 14:45:03 -0600, Don Foreman wrote:
On Fri, 27 Jan 2006 19:51:53 GMT, Ignoramus13653
wrote:

On Fri, 27 Jan 2006 13:45:18 -0600, Don Foreman wrote:
On Fri, 27 Jan 2006 17:30:16 GMT, Ignoramus13653
wrote:

I won a Sun "refrigerant recovery unit" in a military auction for
$55. I have not picked it up yet, but it looks to have been used very
lightly, if at all (I'll see, it is rated A4). As I learned after I
won it, it is for "old style R12" systems, whatever that is. So it is
not that valuable.

My issue is that I need a vacuum pump. Are vacuum pumps in these
machines any good and can they be ripped out and outfitted with
regular 1/4" NPT fittings.

Thanks

Depends on why you want a vacuum. Such a pump should pull at least
28" of Hg, which is useful for some purposes but not for others.
It's fine for degassing molding materials, not nearly enough vacuum
for sputtering mirrors or metallization.

What would you use it for?

My first use would be desoldering. I am not sure about future uses and
whether I would need "deep vacuum". Good question though. In terms of
percentage of air that such pumps remove, would you know how good are
these refrigerant removal pumps?

Thank you

If it pulls 28 in of Hg, and atmospheric pressure is 29.9 in
Hg.......do the math!

It would work fine for desoldering if you have a vacuum reservoir.
The pumps are low volume pumps but a reservoir could provide a pulse
of vacuum when you open a valve. A suitable valve might be the little
pushbutton valve in a cheap blowgun, as:
http://tinyurl.com/cweo9

I've seen these at HF for about $2.

A suitable vacuum reservoir might be an old 16.4 oz propane bottle.

Thanks Don. I will see what kind of pump is in that unit, and will try
to decide, but your information is very helpful. As far as "do the
math" is concerned, you are right, but the answer depends on just
exactly how much "above 28" the vacuum is.

i

It does indeed! Some pumps in good condition will go down to
microns of Hg. That would make no noticable difference for degassing
or soldersucking.

On Sat, 28 Jan 2006 00:01:46 +0000, (DoN.
Nichols) wrote:

According to Rex B "":

Glenn Ashmore wrote:

[ ... ]

If it is in good condition the pump should pull down into the mili-torr
range. My cheapo little RobinAir will easily peg a normal vacuum gauge.
It can't keep up with my Sargent-Welch but then you can't pick up the S-W
and haul it around the shop.


I have a medical vacuum pump.
Would it be suitable for A/C system evacuation?

I strongly doubt that. Medical vacuum pumps are used for
removing fluids pooling in a area of surgery -- kind of like the pump
put in your mouth at the dentist's. Medium flow, not particularly
strong vacuum.

Strong vacuum would be likely to damage tissue if the tissue
gets pulled against the intake.

Of course -- there could be other uses of vacuum in medical
technology which could require high vacuums -- but I don't know what
they might be.

Any idea if medical pumps have to meet a lesser spec in terms of in/Hg?

I strongly suspect so.

The pumps used for A/C service are about the grade of the oil
wetted pumps used as "fore-pumps" in high vacuum systems. They get the
pressures down to a level where other technologies can take over --
turbo pumps, molecular sieve, oil-diffusion, and various others which
can't even be *started* near atmospheric pressure. And those fore pumps
need to run for quite a while to get even a fairly small vacuum chamber
down to the pressure levels where the other technologies start out.

And the oil wetted pumps are really *too* good for something
like desoldering. For that, I would suggest something like the Gast
brand rotary graphite vane pumps. The oil wetted should be run for a
long time after the majority of the air is pumped out -- in part to
remove gases which have been taken up into the oil during the first part
of the pumping. As they start, you hear a sound sequence like:

Glurk Glurk glurk Poketta Poketta poketta poketta ... tick tick
tick "murmur" ....

with the "Glurk"s being large bubbles of air being passed through the
oil bath, the "poketta"s being much smaller bubbles, the "tick"s even
smaller bubbles, and the "murmur"s being the continuing motion with
nothing measurable really being pumped.

The first few moments -- for however long the "Glurk"s continue,
the exhaust side will carry some oil vapor with it. A lab pump usually
has a trap on the exhaust to condense that oil and drip it back into the
main pump. Sometimes, the exhaust is pumped to the outdoors, instead.

Enjoy,


I did! That is a wonderful description of what it sounds like and
what's doing. Loved it!