Sciencemadness Discussion Board - Proper tubing for vacuum - what works best?

Proper tubing for vacuum - what works best?

RogueRose - 30-12-2017 at 03:06

I have some thick nylon (thread) reinforced vinyl tubing that works pretty well for vacuum but when it gets warm, the tube still collapses. Is this adequate tubing and I need to figure a way to mitigate the heat issue or is there a more rigid tubing type that can withstand temps (~140F)?

vacuum hose

Heavy Walter - 30-12-2017 at 04:20

Hi
There are some reinforced with a spring.

Fulmen - 30-12-2017 at 04:57

You could try running a length of coarse rope through the tube. At high vacuum the flow rate is usually negligible.

Magpie - 30-12-2017 at 09:44

Buy red rubber hose for vacuum at Carolina Biological.

RogueRose - 30-12-2017 at 10:32

Thanks for the replies. The idea of putting a rope in the middle is attractive!..

aga - 30-12-2017 at 11:28

I find that orange/black gas pipe is rigid enough and easily available.

Fulmen - 30-12-2017 at 13:14

Rigid rubber hoses used for gas and petrol usually work fine. I discovered the other trick while vacuum-bagging some fiber glass, the cheap hose I had available would collapse quite fast. Stuffing it with breather cloth was enough, a bit of rope should do the same.

unionised - 31-12-2017 at 10:10

Quote: Originally posted by Fulmen

You could try running a length of coarse rope through the tube. At high vacuum the flow rate is usually negligible.

It certainly would be.
The flow rate is low but (obviously) the pressure available to drive that flow rate is tiny.
Vacuum systems use big wide pipes for a reason; filling them with rope will massively reduce the pumping speed.
Filling a big tube with a bunch of smaller tubes is less bad.
"wedging" the pipe open with a spring is one of the better options- that's why the commercial products do it that way.

Radium212 - 1-1-2018 at 10:08

I tend to use tubing only when necessary, and have many lengths of bent or straight copper pipe. I join the copper pipe to other things with small pieces of silicon tubing, but keep it short enough that it can't really collapse.

happyfooddance - 2-1-2018 at 08:53

Quote: Originally posted by Radium212

I tend to use tubing only when necessary, and have many lengths of bent or straight copper pipe. I join the copper pipe to other things with small pieces of silicon tubing, but keep it short enough that it can't really collapse.

I do the same thing, except I use hdpe tubing. It is pretty easy to handle, and you can shape the tubing with heat if need be.

happyfooddance - 10-1-2018 at 22:30

Quote: Originally posted by Magpie

Buy red rubber hose for vacuum at Carolina Biological.

Magpie, how does this hose do with acids? Nitric, HCl, etc...? I have seen it before, it looks very nice to deal with except for being opaque.

Cezium - 11-1-2018 at 01:29

Used something like this and it is good enough, doesn't collapse even with two stage oil vacuum pump and is also decently chemically resistant.

https://www.ebay.com/itm/Blue-4mm-Vacuum-Silicome-Hose-Inter...

Magpie - 11-1-2018 at 06:04

Quote: Originally posted by happyfooddance

Quote: Originally posted by Magpie

Buy red rubber hose for vacuum at Carolina Biological.

Magpie, how does this hose do with acids? Nitric, HCl, etc...? I have seen it before, it looks very nice to deal with except for being opaque.

It is very nice to deal with. I have used it in all my experiments for years with no sign of chemical attack.

If you submerged it in nitric acid overnight I suspect it would be degraded.

DrP - 11-1-2018 at 06:44

Quote: Originally posted by Magpie

Buy red rubber hose for vacuum at Carolina Biological.

I used to use silicone rubber. I preferred it to the red tubing in case any solvents accidently got sucked into it... they come back out red! lol. I used rubber bungs made from clear silicone rubber too as solvents don't leach out the red dye.

PS - Actually - sorry, the stoppers were silicone rubber, I do not know what the tubing was - Was clear though to avoid red dye from the rubber getting dissolved in.

Electra - 14-1-2018 at 15:36

The cheapest solution I can recommend is black rubber hose from your local automotive store. I usually get 3/8" ID rubber hose from autozone or a similar store, and they cut it to any length you want. So far this is the cheapest and strongest vacuum hosing I have come across. I've never had issues with it collapsing under vacuum at all. I can't even force it to collapse by pulling a full vacuum and squeezing it, it's just too thick, as it is rated to positive pressures of 100-250psi. So far I've used this hosing for over 2 years and have never had any issues with solvents or degradation of the hose, despite how often solvents get sucked through my vacuum.

The hoses you find on scientific supply websites are similar in thickness, but you will certainly pay much more.

https://www.autozone.com/plumbing-hosing/rubber-hose

[Edited on 14-1-2018 by Electra]

Magpie - 16-1-2018 at 16:02

I finally called CarolinaBiological, it seems their website is down.

They want $44/50ft. Don't sell it by the foot. I used to be able to buy it in 15ft sections.

The price is good if you can buy 50ft.

NEMO-Chemistry - 16-1-2018 at 19:12

I use same stuff they use for propane etc, the fairly rigid orange stuff. Or I use black thick airline type.