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2mm ID tubing for Pitot tube + does anyone know about pitot tubes
pigeondave - 9/1/22 at 11:20 PM

Hi all,

With such a mix of professions on here I was wondering if anyone had a source for tubing, ideally ptfe but I think anything will do.

I have a pitot tube which I'd like to hook up to a manometer and need probably about 15m (to be on the safe side) of some small tubing.

Would you think the tube should be the same size as the outlets on the pitot? I as as at the moment I've bodged some 5mm ID onto the pitot even though the outlets are 2.5mm dia. I don't think this would be right for a long run of tube as the extra cross-sectional area will act as a damper and the sensor wouldn't read accurately.

Thoughts please?

Mike Wood - 10/1/22 at 12:19 AM

This might be of use?
https://www.lasaero.com/products/article/I00I217XF

Cheers
Mike

pigeondave - 10/1/22 at 08:14 AM

Thanks
Looking on the phone, it appears that they only do 6mm ID?

femster87 - 10/1/22 at 08:24 AM

Here is who I use

http://www.processengineeringsupplies.co.uk/shop.htm

JAG - 10/1/22 at 09:31 AM

quote:

I don't think this would be right for a long run of tube as the extra cross-sectional area will act as a damper and the sensor wouldn't read accurately


Your partially correct but I don't think it would affect the accuracy but the damping behaviour you mention will change the speed of response.

Pitot tubes work by generating a pressure differential, the larger bore tube increases the volume of 'fluid' in the system therefore any change in pressure takes longer to be visible to the sensor.

indykid - 10/1/22 at 09:32 AM

4mm polyurethane/nylon/PTFE pneumatic tube is 2-2.5mm ID and easy to get hold of. It also suits standard pushfit fittings. The PTFE variant is eyewateringly expensive compared to the others though.

Whether the volume of the tube you have at the minute is significant or not probably depends how transient the measured flow is. If you're really worried, can you shorten the distance between pitot tube and sensor?

gremlin1234 - 10/1/22 at 11:16 AM

could you use teflon mig welder liner tube?

like
https://www.r-techwelding.co.uk/3m-teflon-mig-welding-torch-liner
or
https://stemweld.co.uk/products/teflon-mig-torch-liner-all-sizes

edit, different colours denote different sizes
https://www.basicwelding.co.uk/blogs/news/how-to-fit-a-teflon-liner-in-a-mig-torch

edit again
just noticed that you want 15meters, so maybe it won't help, unless you can gat a bulk length


[Edited on 10/1/22 by gremlin1234]

coyoteboy - 10/1/22 at 03:52 PM

Smallest inner diameter possible unless you're looking for practically static pressure readings.

pigeondave - 10/1/22 at 05:52 PM

quote:
Originally posted by indykid
4mm polyurethane/nylon/PTFE pneumatic tube is 2-2.5mm ID and easy to get hold of. It also suits standard pushfit fittings. The PTFE variant is eyewateringly expensive compared to the others though.

Whether the volume of the tube you have at the minute is significant or not probably depends how transient the measured flow is. If you're really worried, can you shorten the distance between pitot tube and sensor?


Brilliant! Thanks for the names of the other materials. You're right PTFE does make me wince and the price.

I'm planning to shorten the lengths as much as I can, but I'm guessing if I can keep the diameter to a minimum too every little helps.

gremlin1234 - 10/1/22 at 07:32 PM

having thought about it, why don't you use copper?
so a quick search found not much, - except pg 3, of this lists 30metre rolls of 0.075inch ~ 1.9mm internal diameter nylon tubing

https://www.johnsonvalves.co.uk/Data/Data%20Sheet%20No.%2032.01-02%20-%20Copper%20&%20Stainless%20Steel%20Tube.pdf

indykid - 11/1/22 at 09:34 AM

If you're happy making your own terminations, 0.5mm ID?

https://www.moddiy.com/products/High-Quality-F4-PTFE-Tubing-%252d-Transparent-(0.5mm-ID-x-1mm-OD).html?setCurrencyId=6

ETA:
Scratch that, 0.3mm diameter on ebay (from China)

https://www.ebay.co.uk/itm/391075062127

[Edited on 11/1/22 by indykid]

pigeondave - 11/1/22 at 01:16 PM

quote:
Originally posted by indykid
If you're happy making your own terminations, 0.5mm ID?

https://www.moddiy.com/products/High-Quality-F4-PTFE-Tubing-%252d-Transparent-(0.5mm-ID-x-1mm-OD).html?setCurrencyId=6

ETA:
Scratch that, 0.3mm diameter on ebay (from China)

https://www.ebay.co.uk/itm/391075062127

[Edited on 11/1/22 by indykid]


I bow to the superior finding skills.

[Edited on 11/1/22 by pigeondave]

indykid - 11/1/22 at 06:09 PM

quote:
Originally posted by pigeondave
quote:
Originally posted by indykid
If you're happy making your own terminations, 0.5mm ID?

https://www.moddiy.com/products/High-Quality-F4-PTFE-Tubing-%252d-Transparent-(0.5mm-ID-x-1mm-OD).html?setCurrencyId=6

ETA:
Scratch that, 0.3mm diameter on ebay (from China)

https://www.ebay.co.uk/itm/391075062127


I bow to the superior finding skills.

I started with '1mm teflon tube' which yielded some 0.71mm bore PTFE on the CPC site so I though maybe there'd be 0.5mm electronicsy stuff, so I googled '0.5 id teflon tube' which yielded the top result, but listed specifically as F4 PTFE so I googled 'F4 PTFE tube' and found the ebay listing for 0.3mm id which is apparently quite reasonably priced and priced per 20m, not per foot!