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I'm pressure testing my system by putting main line water pressure on, closing a ball valve and a solenoid valve and letting it sit with a pressure gauge on it. I've had leaks on pretty much every connection on the main line. The main line is 1 1/4" poly pipe, and the manifolds are PVC.
I have a fitting on the manifolds that is female 1 1/4 threads on the manifold side and 1 1/4" poly barb on the other. I had some leaks on the threaded joints and some on the barbed joints. The threaded joints took about 1/2 turn more and they sealed, but the poly/barbed joint isn't as cooperative. I have double pipe clamps on all of them and even went to three on one. What I don't like about this particular fitting is that it only has about three barbs on the end then about an inch with nothing before the poly pipe bottoms out. Does anyone have any advice to get these barbed fittings to seal. A friend told me a plumber he worked with used some kind of compound on the barbed joint to seal it, but I've never heard of it before. Is there something that will work for this? Also, any advice on a fitting that may be better than the one I have. I will remake my manifolds if I have to, to accomodate a better fitting.

I've attached a link to pretty much the same fitting I am using. Its all that was available here, Menards, Lowe's and the local hardware store all had the exact same fitting.

Also is there anything a person can do with the thin wall irrigation pipe to make it seal better. I read some posts on heating it, but didn't do that for fear of stretching it. I used a rubber hammer and tapped the fittings onto the pipe, the clamped them.

I wasn't able to find good quality clamps either. These don't seem available anywhere. I have stainless clamps and even got some from Napa that seemed a better quality but was able to strip them too with enough pressure. I could strip them with a nut driver and easily with a 1/4" socket and ratchet.

Any advice will help.
http://www.sprinklermart.com/product_p/1435012.htm
Thanks
TeaMan

I wanted to post a little more information. When I pressurize the system it seems to drop about 2 PSI within the first half hour or so and then will hold about 60 psi for about 12 hours. It's somewhat hard to tell exactly on the pressure because our temps are swinging from about 60 degrees during the day to as low as 34 degrees at night. I actually had a 2 to 4 psi increase this morning from last night, but lost about 10 psi during the day today. I did find a drip on one fitting that I put a third clamp on as mentioned before. I tightened it also.

Could I also be losing some pressure from my solenoid valves? They don't have any power on them yet, I'm manually operating them. I did notice when I remove the pressure to fix a leak and repressurize, they all seem to spit water out before sealing. They are rainbird CPF series valves.

I'm stumped why it'll hold pressure for 12 hours and then drop over the next 8 hours. I seem to be down to one fitting that is still giving me problems.
TeaMan

Thanks for the replies. I googled the two ideal clamps you recommended but they don't resemble the picture you showed. They resemble the ones I'm using but may definitely be stronger. I did see some that looked like your picture too, but would be leary to buy them without actually touching them unless a specific part number was recommended and I'd be sure someone else like you has used them. Would you have a specific part number for one like the picture, or would you say that the Ideal clamps (6320 or 6820) would be the ticket?

The poly I am using is CPL Irrigation 100 PSI pipe. The only number on it other than what looked like footage markings was 1115207C000. This is the only pipe I can get somewhat locally. If it's bad pipe, I could always replace the main, but I'd hate to replace all the laterals, I have over 2000 feet down and probably 700 of it is backfilled.

I have a torch, a small one for light plumbing jobs, but also a heat gun. I'm a little more comfortable with the heat gun, it is slower but easier to regulate the heat. I could try that next along with a better clamp. I've read several posts on heating the poly, and with Mitchgo's advice I could take it inside in a more controlled environment, put the poly on the fitting with heat, and attach it to a coupler in the field after I screw the coupling back together.

Mitchgo, I'm not sure what you mean about back leading to the manifold. Do you mean to put the fitting on the manifold and poly together first, then go to the coupler? Please explain. The poly pipe comes into the manifold pretty straight. The poly is in a trench and not covered, so it can move as it needs to while I make connections. The only bend may be the natural bend of the poly itself that wouldn't come out when I unrolled it in the yard in the sun to straighten it out. I would say it's not too bad.

As for clamps. The main clamps I am using are Murray goldseal Pro Series. Only number on them is EHF20SS-38P. The have a recommended torque of 30 to 45 inch pounds. I also got some from the local hardware store that are Ideal 6716-1. They seem slightly stronger, but only slightly than the other clamps.

I have a friend that is a local plumber. I will ask him also if he has something stronger than what I have.
Wet Boots or Mitchgo, if you have a specific part number of clamp you use and feel would help me out, please offer it up. Wet Boots, if the ones you already specified are what you think would work, I will go that way. The one you pictured seemed a little more beefy though, unless my searches didn't return the right clamps.

Again, thanks for the advice. Sorry for more questions. With my limited local resources where I can't actually see the clamp, it's hard for me to be sure of what to get. I have to rely on those of you with experience.

TeaMan

Thanks for the advice and tips guys. I have a couple options to try now. I'm not going to fill the trench around my manifolds until the leaks are done, so I can start with Wet boots suggestion to try two new clamps one more time applying a little heat. If that doesn't work, I suspect the pipe has stretched at the fitting, and I'll replace a couple feet as you suggested Mitchgo. I did find some pretty heavy duty clamps at a NAPA auto parts store in the next town yesterday. They look very much like the picture you provided Wet boots. I'll replace the weaker clamps with these and see if it goes away.

As far as finding the leaks. I just ran my finger under the fittings and it it got wet, it was a leak. I was disappointed to find out that the leak moved from fitting to fitting. One would be fine for a couple days, and develop a very slight leak later. I think I'm down to one fitting that is giving me issues.

Again Thanks
TeaMan