A look at an Ace compression fitting

I got my fittings from Ace. Compression fittings for 5/8" and 3/4" hose. I want to look at one.

I don't have a caliper -- I'm not even sure if that word is okay without an "s" on the end -- just a tape measure. But I want to take some measurements anyway, crude as they will be. Maybe I'll get a caliper sometime and do this exercise over. Meanwhile ...

I'm looking at the mid-hose mender:

When you take the green caps off you're left with one black piece which includes

1. the flow tube you slip the hoses onto,
2. the threads that the caps screw onto, and
3. the teeth that the caps compress when you tighten them, to hold the hoses in place.

Measured at the flow tube, the piece is two and an eighth inches long.

The two caps are identical, far as I can tell, and the black piece symmetrical.

This photo of the disassembled Snip-n-Drip fitting shows a comparable design:

To use the fitting, you slide the cap onto a hose, fit the hose over the tube and under the teeth of the fitting, and push the hose and fitting together as far as they go; then screw the cap onto the fitting, which compresses the teeth and keeps the fitting and hose together. Repeat for the other side, and you're done.

By the way, the threads on the cap and fitting are not garden hose threads. Outside the threads of a male GHT, I measure one and one sixteenth; on the Ace fitting, about one and three eighths.

Oh, and I noticed that the fittings as received had the caps only loosely screwed on. That's probably so the teeth aren't already compressed the first time you use the fitting, and you can fit the hose in.

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That opening in the cap, that the hose goes thru: just about an inch. That means a 5/8" hose will fit thru it even if the hose wall is 3/16" thick. But a 3/4" hose won't go thru if the wall is more than 1/8". Won't slip thru, anyhow.

Real-world conditions often override dimensional estimates. You may have no trouble getting a fat 3/4" hose thru the hole in the cap. I may not, either, when the time comes. For now, I'm just looking at a tape measure and looking ahead.

I'd say the cap will fit easily on almost all 5/8" hoses; but there will be a lot of 3/4" hoses where the cap doesn't fit.

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The flow tube that the hose fits on: I measure 5/8" OD and just under 1/2" ID. The OD allows a 5/8" hose (measuring 5/8" ID) to fit nicely. A 3/4" hose will fit loosely on the tube. To fit easily under the teeth, the hose OD wants to be about one and a sixteenth max, same dimension as the male hose thread OD.

The OD of the tube was not what I expected. I thought it would be somewhere between 5/8" and 3/4". An average of the two, perhaps. Nope. I expected the tube OD to be something over 5/8" for a snug fit. Dunk the end of the hose in hot water for a moment and it goes on easy, snug. Nope. So if the tube cannot be more than 5/8" OD, and the tube wall has to be a little over 1/16" then the tube ID comes out to less that half an inch. Say 1/32" less.

For a tube of that diameter, the cross section area is only a little more than half that of a 5/8" hose.

Q: Can I get a half inch hose onto that tube in the Ace fitting? I'll have to try the hot water trick. If the hose goes on, then my idea about bigger flow tubes could work.

What idea?

if the fitting is big enough that you have to force it into the hose, maybe it is big enough that it doesn't restrict the flow, and maybe the 5% pressure-loss problem would go away.

That idea.