I picked up a small fridge compressor with the idea of playing around using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).


If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.


As part of the terminals to the motor there appears to be a thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)



Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf



I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.


Any ideas?



Thanks.

On Sep 25, 6:31*am, "Dennis" wrote:
I picked up a small fridge compressor with the idea of playing around using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).

If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.

As part of the terminals to the motor there appears to be a thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)

Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf

I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.

Any ideas?

Thanks.

The link (page 7 only) did not have a wiring schematic. But hermetic
compressors use induction motors. There should be a start relay (most
likely a positive temperature thermistor, in series with the start
winding).
Yes the motor is stalled, because the pressure must equalize between
power on/power off cycles, as there is very little starting torque in
these motors. This is true for refrigerators and air conditioning
units.

ignator

"ignator" wrote in message
...
On Sep 25, 6:31 am, "Dennis" wrote:
I picked up a small fridge compressor with the idea of playing around
using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).

If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.

As part of the terminals to the motor there appears to be a thermal
overload
switch, it gets warm but not hot (my guess ~30 Celius)

Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf

I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.

Any ideas?

Thanks.

The link (page 7 only) did not have a wiring schematic. But hermetic
compressors use induction motors. There should be a start relay (most
likely a positive temperature thermistor, in series with the start
winding).
Yes the motor is stalled, because the pressure must equalize between
power on/power off cycles, as there is very little starting torque in
these motors. This is true for refrigerators and air conditioning
units.

ignator

==================================

I had a good look around and could not find a full data sheet, even
ferreting through the chinese language website didn't help.

I pulled the pump out of a very small refrigerator (probably 20 Liter
capacity). The wiring was very simple and looked like it just went via the
thermostat then direct to the compressor. Is the thermistor likely to be
internal?

When I tried to restart the motor it was with the intake & exhaust both open
to ambient atmospheric pressure. Is there pressure internally that needs to
bleed back or something to reduce the required starting torque?

Thanks for the reply.

Refrig compressors are considered "low torque". They will
typically only start if the pressure on suction and
discharge sides are equal. Sounds like you need a high
torque compressor, or a hard start kit.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


On Sep 25, 6:31 am, "Dennis"
wrote:
I picked up a small fridge compressor with the idea of
playing around using
it for a vacuum pick up tool for small electronics parts,
but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a
quiet hum like
the motor is stalled (motor is not running & there is no
airflow).

If I disconnect again then wait a minute or two before
reconnecting it
powers on fine and will run fine - I've let it run for 5
minutes
continuously with no problems.

As part of the terminals to the motor there appears to be
a thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)

Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf

I vaguely recall something about fridges having protection
against rapid
cycling of the power for some reason - but that could be
rubbish. If there
is some sort of anti-short cycle timer it must be inside
the compressor
housing itself.

Any ideas?

Thanks.

Small refrig meter the refrigerant with a capillary tube. By
the time the compressor restarts, the suction and discharge
pressures are equal.

Try calling a refrigeration repair place near you, and ask
about hard start kits.

Note, the lubricting oil in the compressor typically is
hygroscopic. Absorbs water from the air. You can change the
oil, and put in ND-30, so the internals don't rust.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Dennis" wrote in message
...

I pulled the pump out of a very small refrigerator (probably
20 Liter
capacity). The wiring was very simple and looked like it
just went via the
thermostat then direct to the compressor. Is the thermistor
likely to be
internal?

When I tried to restart the motor it was with the intake &
exhaust both open
to ambient atmospheric pressure. Is there pressure
internally that needs to
bleed back or something to reduce the required starting
torque?

Thanks for the reply.

"Dennis" wrote in message
...

"ignator" wrote in message
...
On Sep 25, 6:31 am, "Dennis" wrote:
I picked up a small fridge compressor with the idea of playing around
using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).

If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.

As part of the terminals to the motor there appears to be a thermal
overload
switch, it gets warm but not hot (my guess ~30 Celius)

Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf

I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If
there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.

Any ideas?

Thanks.

The link (page 7 only) did not have a wiring schematic. But hermetic
compressors use induction motors. There should be a start relay (most
likely a positive temperature thermistor, in series with the start
winding).
Yes the motor is stalled, because the pressure must equalize between
power on/power off cycles, as there is very little starting torque in
these motors. This is true for refrigerators and air conditioning
units.

ignator

==================================

I had a good look around and could not find a full data sheet, even
ferreting through the chinese language website didn't help.

I pulled the pump out of a very small refrigerator (probably 20 Liter
capacity). The wiring was very simple and looked like it just went via the
thermostat then direct to the compressor. Is the thermistor likely to be
internal?

When I tried to restart the motor it was with the intake & exhaust both
open to ambient atmospheric pressure. Is there pressure internally that
needs to bleed back or something to reduce the required starting torque?

Thanks for the reply.







I found a wiring diagram on the frige metal work.

http://www.metalworking.com/dropbox/VacPumpWiring.JPG


It shows an overload protect device. The overload and the start cap are
inside or at least part of the compressor. There is a small plastic cover on
the side of the compressor, I'll pull it tomorrow and see what it conceals.

"Stormin Mormon" wrote in message
...
Small refrig meter the refrigerant with a capillary tube. By
the time the compressor restarts, the suction and discharge
pressures are equal.

Try calling a refrigeration repair place near you, and ask
about hard start kits.

Note, the lubricting oil in the compressor typically is
hygroscopic. Absorbs water from the air. You can change the
oil, and put in ND-30, so the internals don't rust.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
.


Ok - I might need to look into this further. According to the data sheet the
compressor is hermetically sealed - I'm not sure if this means the
oil/lubrication is not refillable.

I'm trying to use it as a vacuum pump (with the exhaust side left open).

thanks

Needs a hard start kit. Most refrigerator repair companies
have them. I fix refrig and freezers, and always have
SEVERAL on the truck.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Dennis" wrote in message
. au...
I picked up a small fridge compressor with the idea of
playing around using
it for a vacuum pick up tool for small electronics parts,
but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a
quiet hum like
the motor is stalled (motor is not running & there is no
airflow).


If I disconnect again then wait a minute or two before
reconnecting it
powers on fine and will run fine - I've let it run for 5
minutes
continuously with no problems.


As part of the terminals to the motor there appears to be a
thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)



Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf



I vaguely recall something about fridges having protection
against rapid
cycling of the power for some reason - but that could be
rubbish. If there
is some sort of anti-short cycle timer it must be inside the
compressor
housing itself.


Any ideas?



Thanks.

The small cover should enclose an overload (black, circle)
and a start relay (looks like... a ... relay).

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Dennis" wrote in message
. au...

I found a wiring diagram on the frige metal work.

http://www.metalworking.com/dropbox/VacPumpWiring.JPG


It shows an overload protect device. The overload and the
start cap are
inside or at least part of the compressor. There is a small
plastic cover on
the side of the compressor, I'll pull it tomorrow and see
what it conceals.

There are typically three tubes coming out. Suction,
discharge, and process. By unbrazing the process tube, you
can pour out the lube oil, and replace with similar volume
of ND30. Rebraze it shut. I've done that, and I use the
resulting compressor to compress air for tires, etc. Works,
for me.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Dennis" wrote in message
. au...

"Stormin Mormon" wrote
in message
...
Note, the lubricting oil in the compressor typically is
hygroscopic. Absorbs water from the air. You can change
the
oil, and put in ND-30, so the internals don't rust.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
.


Ok - I might need to look into this further. According to
the data sheet the
compressor is hermetically sealed - I'm not sure if this
means the
oil/lubrication is not refillable.

I'm trying to use it as a vacuum pump (with the exhaust side
left open).

thanks

Dennis wrote:


When I tried to restart the motor it was with the intake & exhaust both open
to ambient atmospheric pressure. Is there pressure internally that needs to
bleed back or something to reduce the required starting torque?


It sounds like problem is the pump doesn't know what you are doing.
It is designed to pause before it can restart to allow pressure
to drain. It doesn't actually measure pressure. It is a timed delay.

-jim

"jim" "sjedgingN0Sp"@m@mwt,net wrote in message
.. .


Dennis wrote:


When I tried to restart the motor it was with the intake & exhaust both
open
to ambient atmospheric pressure. Is there pressure internally that needs
to
bleed back or something to reduce the required starting torque?


It sounds like problem is the pump doesn't know what you are doing.
It is designed to pause before it can restart to allow pressure
to drain. It doesn't actually measure pressure. It is a timed delay.

-jim


Yep - took the cover off and found a device marked QP2-33. Its a positive
tempco resistor. It has a 100 second reset time after starting the motor.

I wonder if these compressors will run continuous (ie an hour at a time)
without issue while pulling a good vacuum?

Thanks for all the replies gents.

Dennis wrote:
"jim""sjedgingN0Sp"@m@mwt,net wrote in message
.. .


Dennis wrote:


When I tried to restart the motor it was with the intake& exhaust both
open
to ambient atmospheric pressure. Is there pressure internally that needs
to
bleed back or something to reduce the required starting torque?


It sounds like problem is the pump doesn't know what you are doing.
It is designed to pause before it can restart to allow pressure
to drain. It doesn't actually measure pressure. It is a timed delay.

-jim


Yep - took the cover off and found a device marked QP2-33. Its a positive
tempco resistor. It has a 100 second reset time after starting the motor.

I wonder if these compressors will run continuous (ie an hour at a time)
without issue while pulling a good vacuum?

Thanks for all the replies gents.

http://www.belljar.net/refrig.htm
http://www.randombytes.net/vacuum_pump.html
http://www.youtube.com/watch?v=7nWz8...eature=related

etc. etc.

--Winston

Compressors like that need cooling. Either, by refrigerant
flowing through, or a fan to blow on the compressor. Should
work, unless it over heats. It does have electric motor in
it, after all.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Dennis" wrote in message
. au...

I wonder if these compressors will run continuous (ie an
hour at a time)
without issue while pulling a good vacuum?

Thanks for all the replies gents.

Dennis wrote:

I picked up a small fridge compressor with the idea of playing around
using it for a vacuum pick up tool for small electronics parts, but it
behaves strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).
These things have thermal starting controls that take a couple minutes
to reset properly before re-starting. So, either leave it running as long
as you need it, or get a different starting control such as a "sinpac
switch" which is electronic, or a potential relay type.

Jon

Can't do it. The compressor is cooled and lubed by the refrigerant and
oil charge. It will overheat quickly without it, and the thermal
shutdown activates.
JR
Dweller in the cellar

On Sun, 25 Sep 2011 19:31:44 +0800, "Dennis"
wrote:

I picked up a small fridge compressor with the idea of playing around using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).


If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.


As part of the terminals to the motor there appears to be a thermal overload
switch, it gets warm but not hot (my guess ~30 Celius)



Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf



I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.


Any ideas?



Thanks.

HOME PAGE:
http://www.seanet.com/~jasonrnorth
--------------------------------------------------

"Dennis" wrote in message
. au...

I wonder if these compressors will run continuous (ie an
hour at a time)
without issue while pulling a good vacuum?

Thanks for all the replies gents.




"Stormin Mormon" wrote in message
...
Compressors like that need cooling. Either, by refrigerant
flowing through, or a fan to blow on the compressor. Should
work, unless it over heats. It does have electric motor in
it, after all.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
.


Thanks - I might stick a timer on it to let it run for a max of 5 or 10
minutes at a time just to be sure. I shouldnt be a problem as I'll be at the
bench when its running.


..........


Just ran it for 30 minutes, its very cool, hardly any warmth noticable at
all.

"Jon Elson" wrote in message
...
Dennis wrote:

I picked up a small fridge compressor with the idea of playing around
using it for a vacuum pick up tool for small electronics parts, but it
behaves strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).


These things have thermal starting controls that take a couple minutes
to reset properly before re-starting. So, either leave it running as long
as you need it, or get a different starting control such as a "sinpac
switch" which is electronic, or a potential relay type.

Jon


Thanks Jon, all sorted.

"JR North" wrote in message
...
Can't do it. The compressor is cooled and lubed by the refrigerant and
oil charge. It will overheat quickly without it, and the thermal
shutdown activates.
JR
Dweller in the cellar




JR, I wonder if we are thinking of the same sorts of compressors?

There seems to be dozens of examples of where people are using them for
vacuum pumps and low volume compressed air sources. I cant remember where I
found the info but supposedly the hermitically sealed ones are the best to
use.

I've run the compressor for about 1/2 an hour. In bright light I can almost
see some mist coming out of the high pressure side. I wrapped some paper
towel around it for a while thinking I'd trap some oil but got nothing -
residual refrigerant perhaps??



I guess the other point is longevity - to me 50 or 100 hours continuous
operation before failure would be acceptable considering my intermittent
use.


On the other hand I know bugger all about fridge compressors otherwise I
wouldn't be asking here!







On Sun, 25 Sep 2011 19:31:44 +0800, "Dennis"
wrote:

I picked up a small fridge compressor with the idea of playing around
using
it for a vacuum pick up tool for small electronics parts, but it behaves
strangely.

On initial power up it runs fine, very quietly.

It quickly/easily pulls down to 20kpa (-80kPa).


However if I disconnect the power and reconnect there is a quiet hum like
the motor is stalled (motor is not running & there is no airflow).


If I disconnect again then wait a minute or two before reconnecting it
powers on fine and will run fine - I've let it run for 5 minutes
continuously with no problems.


As part of the terminals to the motor there appears to be a thermal
overload
switch, it gets warm but not hot (my guess ~30 Celius)



Heres a link to the data sheet:

http://www.transtech-co.jp/electroni...ompressor7.pdf



I vaguely recall something about fridges having protection against rapid
cycling of the power for some reason - but that could be rubbish. If there
is some sort of anti-short cycle timer it must be inside the compressor
housing itself.


Any ideas?



Thanks.

HOME PAGE:
http://www.seanet.com/~jasonrnorth
--------------------------------------------------

"Stormin Mormon" fired this volley in
:

I wonder if these compressors will run continuous (ie an
hour at a time)
without issue while pulling a good vacuum?

No, they won't, but not so much for the cooling aspect (although that's an
issue).

They're designed to run in a positive pressure condition. At a vacuum,
arcing often begins inside, due to insulation breakdown.

LLoyd

On Sun, 25 Sep 2011 09:34:20 -0400, "Stormin Mormon"
wrote:

Needs a hard start kit. Most refrigerator repair companies
have them. I fix refrig and freezers, and always have
SEVERAL on the truck.

That, and refrigeration compressors aren't supposed to be started
with head pressure on them - if you leave them off for a few minutes
the pressures will equalize naturally. That's why shop air
compressors have check valves to the tank, and an unloader line that
is vented when the pressure switch turns off - the tank retains
substantial residual pressure for hours.

You might need to rig the exact same system, get a pressure switch
with an unloader, and a check valve to the receiver.

The little round oveload on the outside of the compressor is there
specifically to pop off if you try short-cycling the compressor before
the load bleeds off. And it's on the outside so it can be replaced
when it goes bad - they do try to think ahead...

Refrigeration compressors are bad for airbrushes or painting - they
have a lot of oil carry-over that will wreck paint jobs with fish-eyes
if you don't filter it all out. The ONLY advantage to using one for
an air supply is when it has to be quiet - So you get a regular
oilless diaphragm compressor and a long hose, and put it out in the
garage where nobody cares about the noise.

And you have to install a sight glass to watch the oil level inside
the refrigeration compressor, or it'll seize up on you. You can do it
with the process tubes on the compressor can and some clear vinyl or
poly hose, but you need to know which two tubes to use, and how much &
what kind of oil it's supposed to contain...

-- Bruce --

On 09/25/2011 08:28 AM, Dennis wrote:

I found a wiring diagram on the frige metal work.

http://www.metalworking.com/dropbox/VacPumpWiring.JPG


Weird! According to that diagram, the condenser and evaporator
motors run continuously, and the lamp is always on. I wouldn't put
too much faith in it.

--
Bob Nichols AT comcast.net I am "RNichols42"