Vacuum pump
07-30-2009, 04:09 PM
#1
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Vacuum pump
Hi,
I'm mid way through assembling a vacuum pump using a fridge motor I scavanged. The motor is quite new and in good condition. What is the prefered way of running these as pumps? i.e. leave them running continously or have them switch on/off automatically. I can hold a constant pressure with the motor running, by using a bleed screw. The only problem I have found with this is that the motor gets quite hot after about 10 minutes. I'd like to be able to use a vacuum switch (I should be able to get my hands on one) to control the motor, but there are too many leaks in the system to be able to set a pressure, leave it for a few minutes, and switch on the motor again to correct for any loss. Also, the motor has an inbuilt switch somewhere that will not allow the motor to turn back on for a few minutes after it has been running, I think it's based on temperature. So, using a vacuum switch would need a reasonably air tight system so that the motor has enough time to cool down.
So, is there any problem with running the motor continously or should I work on making it more air tight? I think that by adding some silicone at certain joints and by adding a volume somewhere along the line I might be able to improve its pressure holding capabilities.
Thanks!
Robert.
I'm mid way through assembling a vacuum pump using a fridge motor I scavanged. The motor is quite new and in good condition. What is the prefered way of running these as pumps? i.e. leave them running continously or have them switch on/off automatically. I can hold a constant pressure with the motor running, by using a bleed screw. The only problem I have found with this is that the motor gets quite hot after about 10 minutes. I'd like to be able to use a vacuum switch (I should be able to get my hands on one) to control the motor, but there are too many leaks in the system to be able to set a pressure, leave it for a few minutes, and switch on the motor again to correct for any loss. Also, the motor has an inbuilt switch somewhere that will not allow the motor to turn back on for a few minutes after it has been running, I think it's based on temperature. So, using a vacuum switch would need a reasonably air tight system so that the motor has enough time to cool down.
So, is there any problem with running the motor continously or should I work on making it more air tight? I think that by adding some silicone at certain joints and by adding a volume somewhere along the line I might be able to improve its pressure holding capabilities.
Thanks!
Robert.
07-30-2009, 04:23 PM
#2
RE: Vacuum pump
it'll get reasonably hot but not overly so unless you lost the oil when releasing the refrigerant (cutting the lines and letting it free vent will blow out part of the oil). i use mine to evacuate refrigerant systems in homes and autos and have left it on a large system for several days and it's never missed a beat in 20+ yrs.
07-30-2009, 07:21 PM
#3
RE: Vacuum pump
As KC says, they do run hot but should be full of oil. They are designed to run more or less all the time usually controlled on and off of course by a thermostat. They hardly ever wear out.
I used to be a service manager for Indesit.
I used to be a service manager for Indesit.
07-31-2009, 06:37 AM
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RE: Vacuum pump
To put it bluntly. The motor should not be made to run continuously to compensate for a leaky system. Fix the leaks. With an artight system the vacuum can be controlled very easily at different levels with a vacuum switch. I purahased a switch from "Aerospace Composites"
Ed S
Ed S
07-31-2009, 06:43 AM
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RE: Vacuum pump
Try this page, most of the enginereing has been done and it works very well. I built one using the 75.00 harbor freght vacuum pump and yet to fail me.
http://www.joewoodworker.com/veneering/EVS/concept.htm
http://www.joewoodworker.com/veneering/EVS/concept.htm
07-31-2009, 09:22 PM
#9
RE: Vacuum pump
it's supposed to get hot, if you look on top of the pump (those of you who recycled one from a refrigerator) it has a tray to collect the water drained off from the "Frost Free" feature of the freezer, this tray is metal and transfers the heat to the water and evaporates it so you don't get it dripping on your floor.
08-03-2009, 02:11 PM
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RE: Vacuum pump
Hi,
Thanks for the great answers. I found a vacuum swith on ebay and it works great. My last hurdle is now some of the wiring going into the motor which I can't figure out. I have the switch placed in the old thermostat leads. It cuts the power as needed. The problem starts though when the motor stops. The pressure switch switches the power back on (after 30 seconds or so) but something prevents the motor starting. A soft humming noise comes from somewhere that I can't pinpoint, and after about 10 seconds a bimetallic fuse type thing clicks, cutting the power to the motor off completely. The bi-metallic strip then cools, clicks back into place, and the motor starts. Does anyone have any idea what is preventing the power going to the motor? And more importantly, why does it do it? I thought it kept the power off if the motor temperature was too hot but it happens when the motor is hot or cold.
I have made a resevoir and while its slowed down the leak rate, it still needs topping off before the motor wants to start running again.
Anyone have any ideas?
If I can't get the pressure switch plan work, I suppose I'll just use my bleed air screw to adjust the pressure and run the motor non stop for the whole curing process, hopefully it won't burn out?!?!?!?
Thanks!
Robert.
Thanks for the great answers. I found a vacuum swith on ebay and it works great. My last hurdle is now some of the wiring going into the motor which I can't figure out. I have the switch placed in the old thermostat leads. It cuts the power as needed. The problem starts though when the motor stops. The pressure switch switches the power back on (after 30 seconds or so) but something prevents the motor starting. A soft humming noise comes from somewhere that I can't pinpoint, and after about 10 seconds a bimetallic fuse type thing clicks, cutting the power to the motor off completely. The bi-metallic strip then cools, clicks back into place, and the motor starts. Does anyone have any idea what is preventing the power going to the motor? And more importantly, why does it do it? I thought it kept the power off if the motor temperature was too hot but it happens when the motor is hot or cold.
I have made a resevoir and while its slowed down the leak rate, it still needs topping off before the motor wants to start running again.
Anyone have any ideas?
If I can't get the pressure switch plan work, I suppose I'll just use my bleed air screw to adjust the pressure and run the motor non stop for the whole curing process, hopefully it won't burn out?!?!?!?
Thanks!
Robert.
08-03-2009, 09:22 PM
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RE: Vacuum pump
you are missing a mac valve in your plumbing, it unloads the pump for starting, there is a link here on this thread for this at joewoodworking.com, its simple to add and it keeps from burning up your pump as well...
08-03-2009, 09:40 PM
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RE: Vacuum pump
I used a vacuum advance retard unit scavanged from a car distributor connected to a microswitch. I little bit of trial and error set the levels for white foam and blue foam.
Something like this
Something like this
08-04-2009, 08:36 PM
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RE: Vacuum pump
Try a one-way valve between your vacuum pump and reservoir. That way leaks from the pump are isolated from the rest of your reservoir and bag.
You can find these in the aquarium section of your local pet store. They're surprisingly effective.
You can find these in the aquarium section of your local pet store. They're surprisingly effective.
08-19-2009, 02:39 AM
#15
RE: Vacuum pump
A vacuum pressure tank will smooth the system out and expand the regulator's effectiveness. I made a tank from a 5 gallon propane tank, unscrewed the original valve and replaced it with a 1/4" barbed hose nipple.
I've tested my frig pump with the airbleed, running the motor continuous and it eventually tripped the built in thermal overload. The overload would NOT RESET ITSELF until I unplugged the motor. I'll bet this is a UL requirement. If this happened in the middle of the night during a lay up, you would be SOL.
I've built the same control switch like Duncker did with the vacuum advance can tied to a micro switch, but I'm not ready to commit to this yet. A commercial vacuum switch would be cheap insurance if I could find one cheap.
I've tested my frig pump with the airbleed, running the motor continuous and it eventually tripped the built in thermal overload. The overload would NOT RESET ITSELF until I unplugged the motor. I'll bet this is a UL requirement. If this happened in the middle of the night during a lay up, you would be SOL.
I've built the same control switch like Duncker did with the vacuum advance can tied to a micro switch, but I'm not ready to commit to this yet. A commercial vacuum switch would be cheap insurance if I could find one cheap.
08-19-2009, 04:08 PM
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RE: Vacuum pump
Combatpig,
I got my Airtrol F 4200-x10-b85 vacuum switch from a local dealer for $21 probably 8 yrs ago.
This switch is adjustable from 0.5" - 10" hg.
Deadband is fixed at about 1" hg.
handles up to 10amps.
I would have gone with one which goes up to 20"hg, but it wasn't in stock, and I was in a hurry.
You can find a local dealer from the airtrol website.
Works great except for vacuums > 10" in which case I switch over to the vacuum advance switch as described earlier.
I have found this switch to be reliable. Adjustable deadband would have been nice, but would have cost more.
There are numerous used "thermoelectric vacuum switches" on the bay, but I couldn't really tell you what they do.
I got my Airtrol F 4200-x10-b85 vacuum switch from a local dealer for $21 probably 8 yrs ago.
This switch is adjustable from 0.5" - 10" hg.
Deadband is fixed at about 1" hg.
handles up to 10amps.
I would have gone with one which goes up to 20"hg, but it wasn't in stock, and I was in a hurry.
You can find a local dealer from the airtrol website.
Works great except for vacuums > 10" in which case I switch over to the vacuum advance switch as described earlier.
I have found this switch to be reliable. Adjustable deadband would have been nice, but would have cost more.
There are numerous used "thermoelectric vacuum switches" on the bay, but I couldn't really tell you what they do.
09-19-2009, 12:42 AM
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RE: Vacuum pump
There is a capacitor in the ac unit that helps start the motor. I am also setting up an airconditoner/ joewoodworker.com vac system. I tried running the motor without the capacitor and it had that soft hum, reconected the capacitor and it runs like a sewing machine.
Walmart $7.00 heavy clear shower curtains make nice bags!Wally also sells clear vinyl in variuos thicknesses in the fabric shop. 100% polyester "backing" is good for the tranfers "felt".
Joewoodworker.com has a downloadable schematic in the direction for his system BTW.
Walmart $7.00 heavy clear shower curtains make nice bags!Wally also sells clear vinyl in variuos thicknesses in the fabric shop. 100% polyester "backing" is good for the tranfers "felt".
Joewoodworker.com has a downloadable schematic in the direction for his system BTW.
ORIGINAL: robert
Hi,
Thanks for the great answers. I found a vacuum swith on ebay and it works great. My last hurdle is now some of the wiring going into the motor which I can't figure out. I have the switch placed in the old thermostat leads. It cuts the power as needed. The problem starts though when the motor stops. The pressure switch switches the power back on (after 30 seconds or so) but something prevents the motor starting. A soft humming noise comes from somewhere that I can't pinpoint, and after about 10 seconds a bimetallic fuse type thing clicks, cutting the power to the motor off completely. The bi-metallic strip then cools, clicks back into place, and the motor starts. Does anyone have any idea what is preventing the power going to the motor? And more importantly, why does it do it? I thought it kept the power off if the motor temperature was too hot but it happens when the motor is hot or cold.
I have made a resevoir and while its slowed down the leak rate, it still needs topping off before the motor wants to start running again.
Anyone have any ideas?
If I can't get the pressure switch plan work, I suppose I'll just use my bleed air screw to adjust the pressure and run the motor non stop for the whole curing process, hopefully it won't burn out?!?!?!?
Thanks!
Robert.
Hi,
Thanks for the great answers. I found a vacuum swith on ebay and it works great. My last hurdle is now some of the wiring going into the motor which I can't figure out. I have the switch placed in the old thermostat leads. It cuts the power as needed. The problem starts though when the motor stops. The pressure switch switches the power back on (after 30 seconds or so) but something prevents the motor starting. A soft humming noise comes from somewhere that I can't pinpoint, and after about 10 seconds a bimetallic fuse type thing clicks, cutting the power to the motor off completely. The bi-metallic strip then cools, clicks back into place, and the motor starts. Does anyone have any idea what is preventing the power going to the motor? And more importantly, why does it do it? I thought it kept the power off if the motor temperature was too hot but it happens when the motor is hot or cold.
I have made a resevoir and while its slowed down the leak rate, it still needs topping off before the motor wants to start running again.
Anyone have any ideas?
If I can't get the pressure switch plan work, I suppose I'll just use my bleed air screw to adjust the pressure and run the motor non stop for the whole curing process, hopefully it won't burn out?!?!?!?
Thanks!
Robert.
09-25-2009, 09:01 PM
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RE: Vacuum pump
Hi Gang,
Today I found just the air tank from an old small compressor at a garage sale. 6" dia. x 20" long. And it has all the appropriate threads for the fittings. [8D] $2.00 ...SWEET!
Perfect for a vacuum resevoir. I bought the Joe woodworker set for guages etc. I will assemble it on the next day the weather is to bad for flying.
Today I found just the air tank from an old small compressor at a garage sale. 6" dia. x 20" long. And it has all the appropriate threads for the fittings. [8D] $2.00 ...SWEET!
Perfect for a vacuum resevoir. I bought the Joe woodworker set for guages etc. I will assemble it on the next day the weather is to bad for flying.
