Sciencemadness Discussion Board

Use Silicone Tubing for High Heat Liquid Transfer?

LuckyWinner - 28-6-2021 at 07:27

silicone tubing can take
-94°F to +392°F (-50 to 200 degrees C)
of temperature and is resistant to ethylene and propylene glycol, the usual
anti-freeze liquids.

could you use this regular silicone tubing for hot propylene 100%
liquid transfer tubing for use in hot buchner funnel filtrations over several hours?

example:
propylene glycol 100%
gets heated to 140C and is getting pumped out of its heating tank
through silicone tubing into a jacketed buchner funnel,
exits out back into the heating vessel.

attach silcone tubing over glass hose barbs and clamp down with hosebarbs.
insulate tubing with foam.

this will work as described leakfree and permanently without any leaks?


why do professional lab suppliers usually only sell stainless steel braided heat transfer hoses and never silicone?

macckone - 28-6-2021 at 19:24

They do sell silicone tubing, usually it is listed as peristaltic pump tubing. Keeping in mind tubing loses strength as it heats up so depending on the temperature and pressure it may not handle it alone, hence the metal jacket.

LuckyWinner - 29-6-2021 at 04:04

Quote: Originally posted by macckone  
They do sell silicone tubing, usually it is listed as peristaltic pump tubing. Keeping in mind tubing loses strength as it heats up so depending on the temperature and pressure it may not handle it alone, hence the metal jacket.


I do know silicone tubing is sold... what I mean is there is none for heating liquid transfer for
chiller/heaters.

at 140C silicone tubing becomes very fragile and rips apart easily?

what over the counter tubing would be a good choice for -15C to 140C then?

macckone - 29-6-2021 at 08:27

silicone will work, you just have to find a thicker tubing and keep the pressure low.
for transfer to a heating jacket, the pressure should not be very high so you may be ok.
You can buy reinforced tubing of various kinds.

example:
https://www.goldleaflabs.com/silicone-tubing-fiber-reinforce...

You can also use FEP or PTFE which are much higher temperature.

Lastly, given that you are using glycol, automotive heater hose should work.
It is designed for 4 atm but a slightly lower temperature.
It will probably work and is very OTC with a low cost.

https://www.oreillyauto.com/detail/c/safety-stripe/belts-hos...

Every material has a strength derating for temperature.
You may have to try several types and see how they work for your application.

wg48temp9 - 30-6-2021 at 02:21

I have dismantled two counter top hot drinks machines. The piping on both looked like silicon rubber. The silicon rubber was attached to the hot water tank, which I assume was continuously hot, had hardened and become brittle at the the parts that where next to the tank. The tank was open to the atmosphere and would have been temperature controlled to about 90C to avoid the water boiling.

Now those machines may have been in continuous operation or at least 8 hours a day for perhaps 5 years judging by the date code on some of its components. So the particular silicon rubber used for the tubing would not be suitable for extended operation at about 90C exposed to water. I suspect silicon rubber has to be specially formulated to withstand 140C when exposed to water for extended periods.

macckone - 30-6-2021 at 06:24

wg48temp9,

Yes, there are various grades of silicone tubing.
And pretty much any tubing exposed to close to boiling water is going to degrade over time.
The plasticizers degrade more than the silicone, hence the hardening.
Even glass degrades over time with continuous water exposure if sodium ions are present at 90C.

5 years is definitely outside of normal lab use.