3/4 Inch Lines and Barb Fittings

[Sandy Wood]

I've got a Tetra 550 pump and I'm using the 3/4 barbed fitting that came with the pump. I also got my hands on some Beckett 3/4 inch corrugated tubing that looks to be perfect for my pond. The tubing fits nicely on the line out from the pump but I can't get it to fit over a 3/4 inch barbed fitting I picked up at the local hardware store. I've tried greasing the fitting but it seems to be bigger than 3/4 inch. I've thought about using 1/2 barbed fittings and then clamping them tight but that seems just crazy. Has anyone run into this before?

 

[Meyer Jordan]

Yep. And that is why I quit using corrugated tubing over 15 years ago.

 

[Sandy Wood]

Ugh. Wish I had done a little research beforehand. I did run across something on the web that indicated that this tubing is measured in outside diameter, not inside.

The search goes on.....

 

[HARO]

I've had good results at the local farmer-type stores (Tractor Supply, Farmers' Co-Op). They carry fittings in PVC, nylon, and brass, and by taking a short piece of the tubing along, I can always find SOMETHING that fits.
John

 

[Sandy Wood]

Good idea. We've got one nearby that I'll have to check out.

 

[sburtchin]

Hope you found what you needed at TSC. If not, here is a trick that works for me most of time. Push something cone shaped into the end of the tubing to stretch it out. The shallower the angle the the better, and the easier it will be to push it in. I use a pencil or a center punch for small tubing. If you need to stretch the tubing a lot, leave it in overnight to stabilize the stretch.

 

[TAHOE]

I had same issues, used my heat gun to soften up the rubber, but still had to "screw" the metal wires part onto the fitting, then clamped with hose clamp.

 

[Sandy Wood]

Thanks for the good tips. I've tried to stretch out the corrugated line but it doesn't want to budge for me. I haven't tried a heat gun but this morning I stumbled across something that may work. I have a bunch of 1/2 inch cutoff sprinkler risers that the tubing fits pretty snug over. I'm thinking about trying to adapt them if I can't find a suitable barbed fitting.

 

[TAHOE]

Thanks for the good tips. I've tried to stretch out the corrugated line but it doesn't want to budge for me. I haven't tried a heat gun but this morning I stumbled across something that may work. I have a bunch of 1/2 inch cutoff sprinkler risers that the tubing fits pretty snug over. I'm thinking about trying to adapt them if I can't find a suitable barbed fitting.

Those might work, you should be able to find an adpater to screw into the 3/4" threads.

 

[sburtchin]

Thanks for the good tips. I've tried to stretch out the corrugated line but it doesn't want to budge for me. I haven't tried a heat gun but this morning I stumbled across something that may work. I have a bunch of 1/2 inch cutoff sprinkler risers that the tubing fits pretty snug over. I'm thinking about trying to adapt them if I can't find a suitable barbed fitting.

It would be a shame for you to have to restrict your output to 1/2". That is more than a 2-to-1 reduction in the cross sectional area of the pipe (4/9ths to be precise). There would also be increased friction with the sidewalls of the 1/2" part of the tube (ref: Manning's formula). You won't loose any head, but I think you would get far less than the 550gph pump rating.

That wire reinforcement can severely limit how much it will stretch. Two solutions come to mind. If you can remove the wire (or snip it at 1/4 inch intervals) for the final 1-1/2" of the tubing it should be stretchable. Alternatively, find a piece of tubing at the hardware store that will fit over the corrugated tubing. Overlap at least an inch and fill the gaps with epoxe cement (hold it vertically and use tape to keep the cement from running out the bottom). Secure with a hose clamp after the cement is hard. Then use a standard barb fitting for that.

 

[Sandy Wood]

My biggest supply will go to a vase that I've plumbed to let water bubble over the edge. It's about 18 inches above the water line so I know I'll need some GPH to get water up and over the top. My other supply will go up to a cast iron water pump that I'll only need it to dribble out of. I'm hoping my 1/2" connections won't reduce it too much. If not, I'll make it all pure 3/4".

Thanks for the advice.

 

[sissy]

sometimes heating the hose a little works at getting a fitting on

 

[koiguy1969]

dip the end of the hose in hot water, don't use a heat gun. hot water isn't going to melt the hose like a heat gun might. I run hot water thru hoses I'm reusing to make them easier to work with.

 

[DrCase]

I Just use a tourch, It only takes a few seconds to soften the pipe up