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Old 01-08-2008, 05:02 PM   #16
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no-hub terminology


Here's something I just learned today. I never actually looked at the boxes the no hub couplings (the exact coupling in your second picture) come in. Want to guess what brand they are?
Mission, Mission is actually a name brand just like Fernco and they probably make all different clamp styles under that name brand. Fernco commonly refers to the two banded couplings but Fernco actually makes the two brands, and ones that are completely banded. It's just like the term Band-Aid. Band-Aid is actually a brand name, the correct term is adhesive bandage.

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Last edited by Marlin; 01-08-2008 at 05:05 PM.
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Old 03-16-2009, 06:15 PM   #17
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no-hub terminology


There are several different types of DWV couplings. Many times people use the manufacturers' name as generic terms.

People typically call an unshielded couplings Fernco couplings, a rubber coupling with 2 ss bands. (Actually, Fernco couplings are plasticized pvc. Not rubber at all.) These couplings are designed and listed to connect various pipe/fittings. Mission makes these too, as do others, but Mission's is the only rubber "Flexible" couplings. They seem to work best as they are more elastomeric and therefore work on oversize pipes.

Flexible couplings also are available with heavy ss shield. These are called ARC's. They are made to provide a joint that doesn't get misaligned from improper backfill, settling, seismic activity, etc.

Shielded transition couplings are frequently referred to as Mission bands. Mission invented these couplings decades ago. They are, in effect, no hub couplings. Same neoprene rubber, same stainless steel, same basic design, except the rubber gasket fits different types or sizes of pipes. This is the class of couplings allowed for Cast iron x plastic connections.

No hub couplings, are designed for cast iron x castiron connections only. Not cast x plastic. The differences on diamters of cast and plastic make the no hub couplings frequently buckle and leak. There are 2 types of no hub couplings. Standard and Heavy Duty. The heavier no hubs are wider and accommodate more clamps. Therefore will usually withstand a greater test pressure. Also, made with higher grade of anti corrosive stainless steel.

There are also Calder style couplings, which are like Flexible couplings but have a center stop similar to a no hub coupling. Sometimes have a stainless steel shield.

All of these couplings need to be torqued to min 60 in lbs.

I hope that helps...

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