Out Of The Mouth Of Babes
This metric plumbing on theses drains/returns presents some challenges. I was considering a few solutions…
- BRS sells metric transition fittings. These would work, but the problem is the metric side of the fitting is a socket, not a slip end*. The plumbing which comes with the tank is already glued up, so I do not have a metric slip fitting to work with. Gary at ProClear is great to work with, and will sell you metric fittings if you need them. You can also order them from China, and get them a bajillion weeks later, if you really like staring at an empty tank.
- On @craftbrews thread, he found a supplier which offers metric/inch conversion unions. This will definitely work, but they are spendy.
This weekend, I was explaining the problem to my fiancé. She picked up the 32mm drain line, and a 1” union I had on hand, and said, “Why don’t you just screw the two sizes together?”
“That won’t work,” I explain, “they are different sizes. See, if you try to screw them together they won’t….”
Except it did. It went together flawlessly.
I was gob-smacked.
I grabbed the 25mm union and a ¾” union, and excitedly screwed them togeth….
Except it didn’t. Completely different sizes.
So I grabbed a ¾” full union ball valve I had on hand, and…
Perfect.
I ordered these fittings from PVCFittingsonline.com. The FUBV is model #FP-PRO-TUBV-ST-007. The 1” union was model number #897-010. You can see the faint imprint of the gasket lube on the union seat, so it's definitely making the seal as it should.
NEXT UP: Dry fitting the returns
*A little bit about PVC plumbing: I see some confusion over terms, people buying the wrong things, and ending up with stuff they can’t use. So here are some terms that might help.
Slip – these are the typical fittings you are used to seeing. The pipe slides into a slip fitting. Connection is made with PVC cement.
Spigot a.k.a. Street fitting – this fitting is the same outside diameter as the pipe. They fit into a slip fitting. You cannot connect a spigot fitting directly to the pipe. When you have an elbow that is spigot on one end and slip on the other, it is known as a Street elbow. These are very handy when space is tight. Connection is made with PVC cement.
NPT (National Pipe Threads) – these fittings have a slightly tapered thread. You will also see them referred to as FPT (Female Pipe Thread), meaning the threads are on the inside wall of the fitting, MPT (Male Pipe Thread), meaning the threads are on the outside wall of the fitting. To make a threaded connection, you will need male and female ended fittings.
You’ll see tons of threads hotly debating the use of Teflon (PTFE) tape on PVC threaded connections. This is not is the preferred method, the reason being it makes it too easy to overtighten the threads, and results in a less forgiving seal. Will it work? Yes. The tape packs down into the thread valleys, which creates a seal, but it puts a lot of shear stress on the fitting, and it will not be as tolerant of vibration and/or loosening without leaking.
But threaded PVC joints should be made with a
non-hardening pipe sealant. Many “pipe dopes” look the same; they are not. Read the label and look for the manufacturer’s recommendation for use on PVC. When you tighten a threaded joint, apply the pipe sealant to the threads of both fittings. Tighten to finger-tight. Not full hand, just until it is snug. Now tighten the fitting 1-2 more turns and no more. As little as 4 turns can crack the fitting.
My personal opinion, as an Architect and reefer, is threaded connections should be avoided. Threaded fittings are designed to rely on pipe sealant. Putting them together without something on the threads will result in a leak – they threads marry together in a way which creates a small gap in the bottom of the threads, which the sealant fills. Teflon tape will pack into this gap, but it’s not what it’s meant for. I don’t want the tank water coming into contact with the sealing compound, and leaching chemicals into the water, and I don’t like to use Teflon tape, because it’s a crappy seal, long term. Lasco systems dives more deeply into this subject, if you need more convincing.
www.Lascofittings.com/threads
