I am looking into replacing a very long 1/2" ABS ring which feeds up to 6 stations from a Purite Satellite RO. I have never been happy with the installation which has had many leaks and breakages over the years due to incompetent installation.
Has anyone used flexible hose for a ring, or even HEP ?
What alternative materials have people used for non heat rings other than the traditional ABS, PVC and PEX ?
Like you we have the traditional ABS pipework on some of our ringmains but mainly on our pre-treatment setups. We do have one pre-treatment setup made of stainless though.
I see no reason why you couldn't use flexible hose. Questions I would ask myself are:
What sort of disinfection is this ring likely to see? If bog standard braided and silicone hosing can be used in the machines being dialoxed, hypochlorited and heated to 85 degrees then surely regular braided hoses can be used for a ringmain.
What kind of pressure will it be holding? Again, bog standard reinforced hosing should easily hold this. Infact, it is probably more suited due to the fact that it could absorb pressure spikes from pumps shutting on and off unless your lucky enough to have those inverter type pumps in your pre-treatment setup.
IMO the pro's are that it is cheap, easy to route, easy to repair, widely available in a range of sizes (and colours if that is important). The only cons I can see is if it should kink if not properly supported/fastened.
Whether the internal surface can be more susceptible to biofilm growth I don't know but with regular cleaning perhaps this could be managed if a problem. If the worst comes to the worst you could replace sections if not all the ring quite easily (access permitting) on an annual basis if you needed for what it costs in materials.
If traditional ring diameter is around the half inch mark to produce enough flow then sourcing hosing of that size may be the only problem - but then again for just 6 stations you're not going to need much more than 6 l/min.
Is domestic plastic push-fit pipe an option? It's basically what is inside portable RO units anyway!