Can coolant hose be this thin?

I'm doing heater hose work under the dash of the old Mazda and ordered some in 17mm and 18mm (in case I measured wrong) from Belmetric.

The 17mm hose on the right in the photo is braided but really thin and flimsy feeling, doesn't even have an internal braid. Is this normal for other OEMs? It's listed for water and fuel, but trying to google braided Continental hose elsewhere shows VW people using it for vacuum so maybe they spec'ed it wrong?

The 18mm feels like coolant hose you get everywhere else, but the 17mm is a better fit on the pipes. This all started because long ago I jammed 5/8" hose on and it worked until recently.

The issue I see is that hose really should be used with a push lock type fitting.  A hose clamp, even the nice full circle spring clamps that the OEMs prefer, will have a small area of poor compression and you need a measure of moosh (technical term) for the hose to seal on a normal barb.

The one on the right has a couple things working against it depending on where you plan to route it. The thin walls will allow it to kink easier and also collapse if the there's any negative pressure on it (suction, cooling, etc). 

If you can route it so it doesn't kink, then use these style clamps: Oetiker

All hoses have a tube, reinforcement and a cover - that 17mm might have enough reinforcement in the cover to meet the pressure rating.  

What's on the lay line for working pressure?  I believe it should work fine.  

In reply to Pete. (l33t FS) :

I thought even push lock hose was thicker, but I've never used them.

I'm leaning towards using the 18mm because of the moosh it has over the 17.

In reply to No Time :

The connections are really short and straight but there's no way I can get any kind of plier tool to reach one of them.

Even the remote spring clamp tool won't fit so at least that one clamp will have to be a screw type.

In reply to Datsun240ZGuy :

72 psi according to Belmetric, should be fine. The thinness just sent my spidey sense off.

72psi may not be enough.  Most heater hose has a 200-250psi max rating.

Cooling system pressure is not radiator cap pressure, it's amazing how much pressure the water pump will be able to generate.  I'll admit to never having tested a suction side thermostat system, but I have measured 45-50psi in a normally functioning cooling system, and well over 200psi in one that had an issue with gee-whiz aftermarket parts shortchanging the thermostat bypass for flow (because shiny threaded fittings are cooler looking than a pressed in tube)

I saw a trick on here once about stuffing some spring into a hose so it won't kink or collapse