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.
Thanks 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 for
this eBay listing with the 1.5mm ID 3.5mm OD variant, do you think that'd be a good idea?
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!
Thanks. 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.
Oh and remember long lengths of very soft tubing has enough elasticity and pressure drop to offset pressure measurements
Only if there is flow? I'd assume this thing has no "bias flow", or is that naive?