What I.D. of tubing would you use with a 1.93mm barbed connector? Where to buy? - Page 1
Forum section: electronics / projects

author: rs20
author_rank: Super Contributor
timestamp: June 08, 2019, 08:59:34 am
content: I got myself aHSCDRRT001PD2A3differential pressure sensor, having not thought ahead to the tubing which I'll need to connect on to its barbed connectors. Obviously it depends on the flexibility of the tube material to a certain extent, but what sort of hose I.D. / wall thickness would y'all recommend to connect on with a nice leak-proof connection? The pressure inside the tubing will be well under 1 psi = 6.9 kPa. The drawing shows a 1.93mm O.D. on the widest part of the barb, which I have confirmed with my calipers on the real part:Also, where would one find and purchase such a tube in Australia (or at least, delivering to Australia?)I've tried one outfit (Gecko Optical) who AFAICT have just taken my money and run offEDIT: turns out there was a mix-up in the mail room and I had packages delayed by a month, Gecko Optical delivered great tubing just fine as it turns out; and a lot of tubing ranges I find online don't go below 1.93mm, others are "request a quote" type places which I would prefer to avoid unless someone can tell me they're actually friendly to hobbyists. It would be nice if the tubing is food grade and/or clear (or at least translucent.) Any and all other advice in the sphere of making pneumatic connections is welcomed.

author: Ian.M
author_rank: Super Contributor
timestamp: June 08, 2019, 09:47:53 am
content: What's the diameter just behind the barb, and what's the diameter of the front edge of the barb taper?Unless the tubing is a very soft rubber, it will be a PITA to get on if its ID is much less than the barb taper, and may not seal reliably if its larger than the diameter behind the barb.Also, those are very small plastic barbs. The tubing needs to be pretty soft or there's a high risk you'll break the barbs while trying to fit it. I'd be looking at thick wall silicone tubing.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: June 08, 2019, 10:41:08 am
content: I'd check ebay for tubing manufacturers. You can usually find listing with multiple diameters dirt cheap, then get a few meters of a few different ones. Find one that fits the best and have a stock of different tubing for future projects!Oh and remember long lengths of very soft tubing has enough elasticity and pressure drop to offset pressure measurements

author: ChristofferB
author_rank: Frequent Contributor
timestamp: June 08, 2019, 10:43:25 am
content: Alternatively, you could get some normal sized plastic double ended hose barbs, drill them out in one end to fit over the sensor port and epoxy them onto them, casting the entire port side in epoxy to stabilise the thin ports might be advantageous too

author: rs20
author_rank: Super Contributor
timestamp: June 08, 2019, 11:58:30 am
content: Quote from: Ian.M on June 08, 2019, 09:47:53 amThanks for the advice. I'm measuring about 1.55mm on straight bit behind the barbs, and I honestly can't get a good measurement on the front edge, maybe 1.7mm or so. This means I'll have to choose between a good seal and it being a PITA; but I think I can make it less of a PITA by flaring out the first mm of the tubing with a drill bit.So I could go forthis eBay listingwith the 1.5mm ID 3.5mm OD variant, do you think that'd be a good idea?Quote from: ChristofferB on June 08, 2019, 10:41:08 amThanks. I found the link above, but that's from China and therefore several weeks away. I really feel like something as simple as silicone tubing should be more readily accessible, but then again I suppose I'm looking for an unusual size.QuoteOnly if there is flow? I'd assume this thing has no "bias flow", or is that naive?

author: Ian.M
author_rank: Super Contributor
timestamp: June 08, 2019, 12:29:00 pm
content: I think 1mm wall 1.5mm ID silicone tubing should deform easily enough to go on to the barb without any trouble. A light smear of silicone and plastics compatible lubricant (i.e. a water based 'personal' lube) on the barb exterior (taking care not to get any in the port) will ease assembly if the tube is a bit too tight. OTOH if you find the tube tends to pop off, a constrictor knot round it behind the barb, done in waxed polyester thread will retain it and give a positive seal.

author: rs20
author_rank: Super Contributor
timestamp: June 14, 2019, 02:28:45 pm
content: Turns out my mail room screwed up, Gecko Optical (as found on eBay) are a good supplier as it turns out. I got the 1.5mm ID x 3.5mm OD tubing, and it works great, very easy to fit and remove, but forms a perfect seal (or much more perfect that my application requires for sure.) Thanks all for the advice!