Banjo type polypropylene fittings for water service line?

[Fitzcarraldo]

I'll be installing another frost proof water hydrant in the next few months here on my farm. Last time around I used threaded brass for the assortment of elbows and nipples needed coming off the bottom of the hydrant. Brass has gone up a lot in 20 years. I could of course use galvanized, but am pondering the possibility of using Banjo schedule 80 polypropylene fittings instead. I already use a lot of Banjo stuff for sprayers and other pump pressure applications. It's rated for 150psi.....(https://m.grainger.com/mobile/product/BANJO-3-4-Elbow-1MJY6?breadcrumbCatId=2133&fc=MWP2IDP2PCP). Does anyone use polypropylene fittings for water service at full street line pressures? Pressure on the line is 125psi. Code isn't a consideration here, (as this is agricultural that no one's ever going to inspect) but longevity definitely is.

 

[Reach4]

What kind of pipe are you using?

 

[Sponsor]

 

[Fitzcarraldo]

The main line is 1 inch schedule 40 PVC. I'll branch off of that with a glued tee and about 10 feet of 3/4 schedule 40 PVC. Another reason I'm considering plastic (polypropylene) fittings between the 3/4 line and the hydrant.....to avoid screwing a brass nipple into a PVC female adapter and worrying about it splitting years down the road.

 

[Reach4]

Yes. Schedule 40 female adapters are to be avoided. What is the fitting on the hydrant, 3/4 MIP?
You could use a 3/4 in schedule 80 PVC S x FPT Adapter. That is thicker.

 

[Fitzcarraldo]

The bottom of the hydrant is 3/4 female npt bronze. So handled by a brass or galvanized nipple between the hydrant and a PVC female npt to socket adapter. So you think the extra thickness of schedule 80 PVC eliminates the chance of it cracking under stress from being expanded by a metal nipple? I had wondered if the extra thickness alone was enough, considering these metal sleeved ones are made as well.
https://m.grainger.com/product/mobile/SPEARS-PVC-Female-Adapter-3FLP6

 

[Fitzcarraldo]

But schedule 80 PVC fittings cost about half of what brass does, whereas polypropylene schedule 80 fittings cost about a fourth of what brass does. Plus the short nipples have handy hex sides built in which makes things easier with open end wrenches instead of pipe wrenches marring all the plastic fittings up. Banjo poly fittings are very tough...I've never cracked one under extreme stress or impact situations. But they're light as a feather and soft compared to PVC.....I wonder if they can handle 125 psi for years, and if they aren't possibly prone to erosion internally from the flow of water over their comparatively soft surface.

 

[Fitzcarraldo]

And for further clarification...in the last few exchanges we're both talking as if I were going straight from pvc pipe glued into one female adapter that will be threaded into the bottom of the hydrant with a nipple (be it PVC, PP, brass, or galvanized). That's actually not the case. I'll be gluing one female adapter fitting onto the 3/4 PVC pipe indeed...but from that point onward there will be a plethora of threaded 90° elbows and nipples. The 3/4 branch pipe will be in a trench 24" deep.....but the hydrant will be one of the 6 foot long models buried 3.5 feet in the ground.....I like the mechanical stability of having them buried deep (no concrete, hard tamped clay only). So at the end of the PVC pipe branch run there will be a post hole dug another 18". Then a street 90, then a 12" and a 6" nipple with a coupling between them, then a 90, then a horizontally placed nipple, then a final street 90 into the hydrant. The last time I put a hydrant in this was all done with brass.....I didn't trust glued schedule 40 PVC elbows and pipe to stand up to all the potential flexing that gets put on these hydrants by cattle sometimes. I even used 8 feet of 3/4 copper pipe with male npt adapers soldered on both ends as my branch line to try to isolate the PVC main line as much as I could from any physical stress from the hydrant getting flexed around. In retrospect it seems a little overkill.....so I'm looking at an all plastic set-up. I still don't trust glued schedule 40 PVC elbows down in the post hole.....which is why I'm asking about using all the polypropylene schedule 80 threaded fittings (or maybe even schedule 80 PVC threaded fittings). Perhaps this is ALL overkill. Would YOU mechanically trust glued schedule 40 PVC elbows all around this hydrant? Assuming one schedule 80 PVC male adapter at the bitter end going into the hydrant.

And while on that subject, would you trust a PVC schedule 40 MALE adapter to thread into the bronze female at the bottom of the hydrant. It's written everywhere that one shouldn't thread a metal male into schedule 40 PVC female threads due to expansion. I've always felt that the male threads on a schedule 40 PVC male adapter were too thin and brittle to be trusted when screwed into a brass female fitting. Any logic there?

 

[Reach4]

I think I might convert to PEX to get that resistance to flex damage near the hydrant. I would use MIP adapters in plastic for PEX, but brass for FIP. I have a manual expansion tool for F1960 stuff. It's slow.

Regarding the threaded PVC, I would not trust threaded schedule 40 PVC, but I figure a glue-on adapter will have heavier duty threads. People use threaded schedule 80 PVC to dangle pumps in wells. While they are often coupled with stainless couplers, they are also often coupled with schedule 120 PVC couplers.

I don't speak from experience.

 

[Fitzcarraldo]

I had been thinking about pex for the very reason of its flexibility. Pex is something completely new to me. Seems everyone's always saying to run it through PVC when putting it in the ground as opposed to direct burial. I imagine that could be largely for the purpose of easy replacement in the future, but also saw references here and there to it possibly being less robust than PVC if something like a piece of gravel were to end up buried against the side of it in a direct burial situation.

What made you choose the expansion system over a crimp system.....the full port nature of the fittings, or do you feel the connections are more stable?

 

[Reach4]

What made you choose the expansion system over a crimp system.....the full port nature of the fittings, or do you feel the connections are more stable?

Bigger fittings ID, yes. Slightly more flexible, altho it is still not really flexible. PEX-A has a slightly smaller permitted bend radius. People said it was better.

I could have used the PEX-A tubing with stainless clamps and the associated fittings. The fittings would have been cheaper and more variety would be available.