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  1. #1
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    Vacuum pulled two 3/8” ports vs one 1/2” port?

    Hello,

    Would you get faster vacuum pulling from
    -two 3/8” vacuum pump ports,
    -one 1/2” vacuum port that splits into two 3/8” ports -one 3/8” port and one 1/2” port off the vacuum pump?

    Which would be the best option because I have a two different tees one with 1/2”, 3/8” and 1/4” port or one with 3/8”, 3/8”, and 1/4” for my JB platinum vacuum pump?

    Thanks.

    Anyone come up with any storage/organization options for their TruBlu vacuum hoses, vacuum gauges and misc fittings/adapter. I was considering getting the accutools case, but may get a pelican case or a Milwaukee packout case...I do also have have Festool systainers/Sortainers and Mikita older style systainers

    Thanks

  2. #2
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    1/2" =.1964 sq"

    3/8 =.1099 sq "
    2 - 3/8 hoses would have a larger sq "
    That if hose are really that size and your pulling through the same size service valves not schrader valves.

  3. #3
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    Mar 2018
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    I think the only way to be sure would be to test your own equipment. That way YOU know how YOUR rig works. Hose size is your biggest deciding factor. If your using trublu 3/4” hoses I would think your almost (if not already) maxing out your pump. So not sure how big of a difference switching between the two trees will be. But I’d recommend grabbing a brand spanking new( & dry) recovery cylinder and clear your evening and run a rack of tests. Write down all the info. When I did my tests I think my pump was almost maxed out and I’ve got two 1/2” appion megaflows with a 7cfm 2-stage bullet pump. Maybe “ITSICEMAN” will chime in. He’s got the trublus I believe

  4. #4
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    Thread Starter
    Quote Originally Posted by servicefitter View Post
    1/2" =.1964 sq"

    3/8 =.1099 sq "
    2 - 3/8 hoses would have a larger sq "
    That if hose are really that size and your pulling through the same size service valves not schrader valves.

    I always be pulling my vacuums through CRT on both high and low side service ports. I had figured two 3/8" hoses would be better than one 1/2" that splits into two 3/8". It would also have one less connection that could possibly leak or cause any issues.

    I also the combination of one 1/2" hose Port and one 3/8" hose Port on the pump connected to two 1/4" connections on the CRTs would have slightly better flow. Perhaps per calculation it would be better, but I wasn't sure in real world applications how much better it would increase vacuum pull down vs a two 3/8" vacuum pump port setup.

    Both hoses are 3/4" diameter with 1/4" fittings on the CRT connections being the bottle neck in the setup, but their is no alternative to that on residential systems.

    I could perhaps install two 5/16" service access fittings and use two 5/16" CRT to increase flow, but would it be worth the extra time and effort in the long run...? I would think not unless it was know to be a long vacuum that would benefit.

    Im just playing with the new hose setup and off gassing the hoses so I won't have to deal with with it when it comes down to business.

    Thanks

  5. #5
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    If it's the blue hoses don't they come with 1/2" ends? I installed on the pump a 3/8 close nip into a tee that has two 1/2” flares

  6. #6
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    Quote Originally Posted by Pres1227 View Post
    I think the only way to be sure would be to test your own equipment. That way YOU know how YOUR rig works. Hose size is your biggest deciding factor. If your using trublu 3/4” hoses I would think your almost (if not already) maxing out your pump. So not sure how big of a difference switching between the two trees will be. But I’d recommend grabbing a brand spanking new( & dry) recovery cylinder and clear your evening and run a rack of tests. Write down all the info. When I did my tests I think my pump was almost maxed out and I’ve got two 1/2” appion megaflows with a 7cfm 2-stage bullet pump. Maybe “ITSICEMAN” will chime in. He’s got the trublus I believe
    At 1300 microns 6 feet of 1/2 hose will allow 7cfm
    Below that your hose is maxed out not your pump.

  7. #7
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    Do you know the formula for conductance speed? Every time I’ve tried to do the math I get it messed up somewhere, But what about 2 - 1/2” hoses? When I was messing with mine I saw virtually no difference in adding a 3rd hose from test port on pump to the refer on vcrt. So I came to the conclusion my pump was at the max for the majority of the pull down

  8. #8
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    This is supposedly good for 1000 and below but I stretched it up to 1300 to get 7 CFM

    Name:  Screenshot_20180823-061334.jpg
Views: 398
Size:  85.8 KB

    6 ft of 3/4" moves 27cfm at 1000 microns.
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  9. #9
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    At 1000 microns im sure your not going to flow anything close to your formula. 1270 microns is 6* boiling point 29.87HG. The air in the system all but gone your boiling moisture out.

  10. #10
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    Cubic feet is cubic feet. Just less molecules per cubic feet at 1000 microns. I didn't pull the formula out of my keister. It's nothing new.
    Feel free to explain how a bigger connecting line is much faster at evacuation because it is or do you doubt that too?

  11. #11
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    Quote Originally Posted by itsiceman View Post
    This is supposedly good for 1000 and below but I stretched it up to 1300 to get 7 CFM

    Name:  Screenshot_20180823-061334.jpg
Views: 398
Size:  85.8 KB

    6 ft of 3/4" moves 27cfm at 1000 microns.
    Thank you. I’ve been looking for one that works for awhile. I was merely saying that the connection sizes aren’t nearly as important as the hose diameter (because of the short length of connection) but when you use that formula you see right off the bat that your not going to find a pump that’s capable of moving that many cubic feet. Maybe a scientific one... like Edwards or something. So really I wouldn’t be stressing too much about the hookup sizes. Your golden pony boy

  12. #12
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    If you could hook up to the system side with a connection bigger than 1/4 there is a huge difference and a pump that pulls to zero vs 15 will have a faster pumping speed in the double digits for sure but at the pressures were talking there isn't a major drop off in cfm's. Again it's just fewer molecules being moved. This is why the greatest speed increase is realized at lower pressures with larger hoses, connections and pumps.

  13. #13
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    I'll have to redo this crappy video but you can't tell me your 7 CFM pump is maxed out with a 1/2" hose when a 1" hose on my 7 can pull this 30# tank down in about a minute. After this video I found out my pump was worn out. So it's even better now.

  14. Likes IceDoctorII liked this post.
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