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Thread: Vacuum Pumps

  1. #41
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    Quote Originally Posted by Hurst11 View Post
    Think of it like a turnpike. Before and after the toll gate traffic is hauling ass and there is very little restrictions, only a small hiccup but everything keeps flowing nicely.
    Quote Originally Posted by dieseldude View Post
    Try breathing through an access tube with the schrader depressed , then try breathing through the same access
    Tube with schrader removed.....
    I meant that I get that the schrader core is a major restriction and should be removed. What I don't understand is that the opening of the port without the core doesn't seem to be larger than a 1/4" charging hose, so why are charging hoses considered to be a bottleneck? Vacuum hoses look like they are much larger than the coreless port opening, which just make the port the new bottleneck, so why are they so effective in speeding up the process? Just looking for an explanation that tastes better than oil...

  2. #42
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    Quote Originally Posted by MSach View Post
    I meant that I get that the schrader core is a major restriction and should be removed. What I don't understand is that the opening of the port without the core doesn't seem to be larger than a 1/4" charging hose, so why are charging hoses considered to be a bottleneck? Vacuum hoses look like they are much larger than the coreless port opening, which just make the port the new bottleneck, so why are they so effective in speeding up the process? Just looking for an explanation that tastes better than oil...
    It's not about the bottleneck.
    Think of it like ductwork friction rate.
    In reality we're moving molecules with basically no pressure at all so if we expect those molecules to find their way to the pump to get pumped out we need to give them the easiest path possible.

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  4. #43
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    Quote Originally Posted by MSach View Post
    I meant that I get that the schrader core is a major restriction and should be removed. What I don't understand is that the opening of the port without the core doesn't seem to be larger than a 1/4" charging hose, so why are charging hoses considered to be a bottleneck? Vacuum hoses look like they are much larger than the coreless port opening, which just make the port the new bottleneck, so why are they so effective in speeding up the process? Just looking for an explanation that tastes better than oil...
    The length also counts. The pressure drop across that 1/4" segment will be a lot less than that + the length of the 1/4" hoses resulting in better airflow. The schrader port is a bottleneck for sure but is made a lot worse once you also add small diameter hoses.

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  6. #44
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    Thanks for all the responses, always great to have an understanding of why I do and don't do things.

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    Name:  vacuum pumps.png
Views: 143
Size:  27.4 KB

    hose size matters

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  9. #46
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    Quote Originally Posted by MSach View Post
    I meant that I get that the schrader core is a major restriction and should be removed. What I don't understand is that the opening of the port without the core doesn't seem to be larger than a 1/4" charging hose, so why are charging hoses considered to be a bottleneck? Vacuum hoses look like they are much larger than the coreless port opening, which just make the port the new bottleneck, so why are they so effective in speeding up the process? Just looking for an explanation that tastes better than oil...
    For the same reason you can move more air through a 10 inch duct vs a 6 inch duct at the same air speed one will be far more noisier and restrictive. Also much more VOLUME for the molecules to be able to fit in. In the smaller hoses all those molecules are bumping into each other and the walls of the hose and just tripping and falling over each other to get out of said hose. Bigger hose allows more of them to fit and travel easier.
    Don’t feel bad if your having hard time understanding it, it took me awhile to figure it out and finally see the light.
    Oh and one more thing, charging hoses have a much higher friction rate I guess you could say than an actual vacuum rated hose due to the way they’re made and the things made up. If you could look through a microscope at the inside of a charging hose vs a vacuum hose, the vacuum hose would be much much smoother with less places for said molecules the hit and bounce off of.

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  11. #47
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    Quote Originally Posted by Hurst11 View Post
    For the same reason you can move more air through a 10 inch duct vs a 6 inch duct at the same air speed one will be far more noisier and restrictive. Also much more VOLUME for the molecules to be able to fit in. In the smaller hoses all those molecules are bumping into each other and the walls of the hose and just tripping and falling over each other to get out of said hose. Bigger hose allows more of them to fit and travel easier.
    Don’t feel bad if your having hard time understanding it, it took me awhile to figure it out and finally see the light.
    Oh and one more thing, charging hoses have a much higher friction rate I guess you could say than an actual vacuum rated hose due to the way they’re made and the things made up. If you could look through a microscope at the inside of a charging hose vs a vacuum hose, the vacuum hose would be much much smoother with less places for said molecules the hit and bounce off of.
    I think I'm getting it. I was just getting too hung up on the bottleneck aspect of it to think about the other effects the hoses have on it after that. Sometimes you really need to be pointed in the right direction...

  12. #48
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    Quote Originally Posted by MSach View Post
    I think I'm getting it. I was just getting too hung up on the bottleneck aspect of it to think about the other effects the hoses have on it after that. Sometimes you really need to be pointed in the right direction...
    My boss would not believe that larger hoses were faster until I showed him a whole bunch of times on installs.
    It's just one of those things that doesn't seem to click for a lot of people.
    Sent from the Okie state usin Tapatalk
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  14. #49
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    Quote Originally Posted by R600a View Post
    My boss would not believe that larger hoses were faster until I showed him a whole bunch of times on installs.
    It's just one of those things that doesn't seem to click for a lot of people.
    Sent from the Okie state usin Tapatalk
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    My boss was up for it but wanted to see it first. I showed him and he immediately jumped on board. Hours turned into minutes.

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  16. #50
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    Quote Originally Posted by ehsx View Post
    Name:  vacuum pumps.png
Views: 143
Size:  27.4 KB

    hose size matters
    Cool chart but so guys know a lot of hoses out there ¼,⅜ etc are even smaller ID than the size line they connect to. IOW a ⅜ hose doesn't have a ⅜ ID

  17. #51
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    this is the kit to get .. Appion SPEEDKIT-V - Vacuum Speed Kit about $474
    or put your own kit together with 2x 1/2in Appion hoses as base purchase

    Appion MH120006EAK 1/2" Diameter Hose, 3/8" FL to 1/4" FL Vacuum Certified Refrigerant Hose, 6', Black .. currently Amazon for $74 ea with free shipping






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  19. #52
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    Quote Originally Posted by MSach View Post
    I meant that I get that the schrader core is a major restriction and should be removed. What I don't understand is that the opening of the port without the core doesn't seem to be larger than a 1/4" charging hose, so why are charging hoses considered to be a bottleneck? Vacuum hoses look like they are much larger than the coreless port opening, which just make the port the new bottleneck, so why are they so effective in speeding up the process? Just looking for an explanation that tastes better than oil...
    Your observation is both intuitive, logical and understandable on the surface.

    Nevertheless this debate has been beaten to death with testing both on the bench and in the field. The result being that 1/4" hoses are an impediment to pulling an industry standard evacuation in a reasonable amount of time. Larger hoses speed the processes greatly. Any restriction that can be removed will help.

    Search YouTube for better explanations/demonstrations by Jim Bergman or Bryan Orr at the HVAC School.
    -Marty

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  21. #53
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    I use a tiny 3# Viot two stage pump rated at 38 microns. It works very well @ 1.58cfm. Speed is not necessarily what you need, it takes time to pull water out of a system, thats when you are supposed to go to lunch. Water freezes at 19"Mg, I prefer to pull systems down slow. Now if you are evacuating a 600 ton centrifugal that blew a tube, yeah, get a big ass vacuum pump with a cold trap in front of it!
    " The more I learn the more I realize how much I don't know"

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  23. #54
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    It's simple. Drink a soda out of a 12" straw. Normal right? Now put 6 of them together and try it again. Much more restrictive. You gotta work for that drink.

    Sent from my SM-N960U using Tapatalk

  24. #55
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    Quote Originally Posted by Zamoramax View Post
    It's simple. Drink a soda out of a 12" straw. Normal right? Now put 6 of them together and try it again. Much more restrictive. You gotta work for that drink.

    Sent from my SM-N960U using Tapatalk
    That are just compare a milkshake straw with a coffee stirer.

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  26. #56
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    Quote Originally Posted by stumpdigger View Post
    I use a tiny 3# Viot two stage pump rated at 38 microns. It works very well @ 1.58cfm. Speed is not necessarily what you need, it takes time to pull water out of a system, thats when you are supposed to go to lunch. Water freezes at 19"Mg, I prefer to pull systems down slow. Now if you are evacuating a 600 ton centrifugal that blew a tube, yeah, get a big ass vacuum pump with a cold trap in front of it!
    Where are those made? I've been thinking about getting a little vacuum pump just because I like to see people's faces when they don't think the tool you have is capable of the job and then it does better than theirs. I just don't want to get some Chinese piece of junk.

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  27. #57
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    I don't believe that is correct. That's a long ways away from boiling water at room temp, much less freezing that water.


    Quote Originally Posted by stumpdigger View Post
    I use a tiny 3# Viot two stage pump rated at 38 microns. It works very well @ 1.58cfm. Speed is not necessarily what you need, it takes time to pull water out of a system, thats when you are supposed to go to lunch. Water freezes at 19"Mg, I prefer to pull systems down slow. Now if you are evacuating a 600 ton centrifugal that blew a tube, yeah, get a big ass vacuum pump with a cold trap in front of it!
    Oh wait, didn't see it till I highlighted it. I thought you were saying inches of mercury. What measurement is Mg ?
    I do a triple evac with nitro to remove non condensables.

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  29. #58
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    Water freezes below 32°F so it could freeze at 18"... 19"... 20" ... doesn't matter what the pressure is at that point. If he was referencing the triple point of water then yes it's much lower than 19"hg

  30. #59
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    Quote Originally Posted by Zamoramax View Post
    It's simple. Drink a soda out of a 12" straw. Normal right? Now put 6 of them together and try it again. Much more restrictive. You gotta work for that drink.

    Sent from my SM-N960U using Tapatalk
    Drink a milkshake from one straw, you can't get anything out due to pressure drop. Put 2 straws in your milkshake and now you can drink it.
    " The more I learn the more I realize how much I don't know"

  31. #60
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    Quote Originally Posted by BBeerme View Post
    I don't believe that is correct. That's a long ways away from boiling water at room temp, much less freezing that water.




    Oh wait, didn't see it till I highlighted it. I thought you were saying inches of mercury. What measurement is Mg ?
    OOOPS, Mg is magnesium, must have meant Hg, surely meant mercury.
    " The more I learn the more I realize how much I don't know"

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