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| Source: SME Industrial Company, Ltd. |
I'm thinkin the fractions are the nominal size, and the decimals are the actual OD. For the half-inch barb, for example, the OD is .03 bigger than half an inch, about 1/32 of an inch bigger. So the ID must be less than half an inch, or the piece would have essentially no thickness.
I want to know the IDs.
In particular, a lot of "hose mender" fittings are sold as suitable for either 5/8" or 3/4" hose. Those fittings must be tighter on the 5/8" hose than on the 3/4". So, how big is the fitting relative to the hose ID? How big is the fitting ID? And does anybody make a "bigger" fitting for each size hose? Because 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.
If the fitting is tight, soaking the end of the hose in hot water for a few seconds will soften it up and the fitting will go in easier.
But apparently they don't make oversize fittings, as the pressure-loss problem hasn't gone away.
Could be the problem is different that I think. Could be the pressure loss results from a disruption of the smoothness of the inside of the hose, and not from the smaller diameter of the fitting. Could be both these factors. If so, then using fittings with a larger diameter would likely reduce the 5% number, meaning less pressure loss from the fittings. That would be an improvement.
All of this is just a guess, at this point.
2 comments:
I said: "I want to know the IDs."
Looking at hose barb fittings at U.S. Plastic Corp, I find a description for a 3/8" HB x MGHT:
This 3/8" HB x MGHT Nylon Adapter is 1.69" long, has a 1.13 hex size and a .250" orifice. This fits tubing with a 3/8" inside diameter.
And a description for a 1/2" HB x MGHT:
This 1/2" HB x MGHT Nylon Adapter is 1.68" long, has a 1.13" hex size and a .375" orifice. This fits tubing with a 1/2" inside diameter.
Good prices on both those items, by the way.
1/2" HB x MGHT translates to "Half-inch Hose Barb (at one end of the fitting) and Male Garden Hose Thread (at the other end)."
The 1.13" hex size is probably 1.125" (one and an eighth) rounded to two decimal places. You might want a 1 1⁄8" wrench, if you are wrenching these garden hose fittings that are made of nylon.
I avoid using a wrench on GHT fittings whenever possible. I know I've said different before. But hand-tight is designed to be good enough for GHT fittings with a hose washer in em. For the faucet adapter I bought the other day, the installation instructions say: 1. clean the threads, 2. tighten it hand tight, 3. check for leaks and tighten it more [only] if it leaks.
This sounds about right to me.
Uh, the IDs of the hose barb fittings.
I suppose this might vary with the manufacturer, dunno really. And the material. But for the fittings linked above I see that
1. A 3/8" hose barb fits a 3/8" hose, which has a 3/8" ID.
2. A 1/2" hose barb fits a 1/2" hose, which has a 1/2" ID.
And
3. In both cases, the ID of the fitting is 1/8" smaller than the ID of the hose.
When I had to replace hose ends on a shrinky hose I got some half-inch hose end menders from True Value, figuring this small size would fit more easily in the shrinky.
Uh-uh. Nope. So I've been thinking about trying the 3/8 size.
Meanwhile, the half-inch mender on my desk has a Hose Barb that measures half an inch outside diameter and about five and a half sixteenths ID.
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