Quote Originally Posted by Martinm210 View Post

In operation, double DDCs likely won't subject the system to more than about 11psi, triples maybe 17psi, RD-30 maybe 14psi.

In practice I think it's been common enough to see dual DDCs that they are relatively tested to a comfort level, but triples are pretty new and not tested a whole bunch.

We don't know about the pressure rating on most parts so it's anybody's guess on that? Perhaps the manufacturers can start posting pressure specs??

Regardless, I suspect the weak point is the fitting/barb pull out on the tubing, especially anything that's been removed/put back together, and particularly with some compression fittings that have small barbs. A 1/2" tube at 17psi is receiving about a 3.5 lb normal force trying to pull the tubing off the barb. I'd be a little uncomfortable with that sort of pressure unless I had a standard barb and worm drive clamp.
I think that with three pumps before loop your asking for leaks. But with them spread out in the loop. It significantly reduces the pressure. At least of the first few fittings/blocks. My analogy wood be put three pumps on a floor. And try to pump the water, 24' straight up a wall. The third pump in the series would have the most pressure on it..

Now if you spread the pumps out. About every 8' they would all have about equal pressure within the pump housing. At least that's how i understand it.
If i am wrong please someone correct me. I don't want to be spreading bad data.