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Old 07-24-2010, 01:06 PM
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More Leaking Hunter PGP Rotors

Today I had to replace yet another Hunter PGP rotor that was leaking around the threads of the cap. Does anyone understand how this failure is happening? This head was at least a couple of years old and I don't believe that it ever leaked prior to this year. When I replaced the head the cap was screwed on to the can so tight that I didn't think that I was going to get it off, so loose was not the problem, overtighten maybe but not loose. I'd like to know if you guys think the failure is in the assembly or the can, if it is because of poor workmanship on that one single thread on the can I have lots of new cans around and I could simply change the can and save a few bucks as the head assembly still seems to work on most of these. I'd be interested in your thoughts as I don't think I am the only one with this issue.

Right now because of the leaking heads and the heads that stop turning, I believe that Orbit makes a better product than Hunter PGP, maybe I got the only bad case that they sent out but for me there has to be something better. I will now don my asbestos suit and await the flaming that is to come.
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Old 07-24-2010, 01:20 PM
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Maybe the head takes a knock and the plastic warps a bit
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Old 07-24-2010, 01:28 PM
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Quote:
Originally Posted by Wet_Boots View Post
Maybe the head takes a knock and the plastic warps a bit
Maybe, but polypropylene is a stiff material, I don't know if it's loaded with anything to affect the stiffness but it is pretty tough stuff. When I look at the threads I can't see how the water could be getting out, I would have thought that the threads would have been eroded and you would be able to see the escape path.
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Old 07-24-2010, 01:34 PM
bcg bcg is offline
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Maybe the PGP is just a POS.

I still replace 3 or 4 cases of PGPs to 1 case of 5000 series heads. Granted, there are more PGPs installed around here but when I replace a 5000 series, it's because it has been physically damaged 99% of the time. When I replace a PGP, it's because the stupid thing is leaking, has launched it's top or it isn't turning anymore 99% of the time.

These leaking PGP threads are starting to feel like a broken record... Maybe Hunter should do something about it?
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Old 07-24-2010, 01:35 PM
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It is not polypropylene, which doesn't see much actual sprinkler use. Rather, it is ABS plastic, one brand name of which is Cycolac ("the football helmet plastic!") ~ Anyway, it is possible to create some built-in stress when the part is molded, not that you would ever know it if the part never takes a hit.


For my money, I would actually look at redesigning the PGP wiper seal. Patents have expired, and it would maybe be possible to "rip off" the Rainbird wiper seal.
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Old 07-24-2010, 01:53 PM
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Years ago I "helped" Hunter discover their leaking seal problem.
We were having issues w/ PGP's leaking from the seals right out of the box. Long story short, the Hunter rep at the time didn't believe us and met us on a jobsite. We quickly found a leaking PGP and the rep gave us one right out of the box that he brought. Turned it back on and it leaked immediately. Turns out that when the head popped up or down it was drawing sand in between the seal and the riser. The VERY simple fix by Hunter was to plug the small hole that was in the cap.
I would venture to guess that the problem with the PGP is still a seal issue in certain soils.
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Old 07-24-2010, 02:00 PM
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The hole in the cap was intended to accept the plastic diffuser screw, to "vandal-proof" the cover
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Old 07-24-2010, 02:24 PM
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Quote:
Originally Posted by Wet_Boots View Post
It is not polypropylene, which doesn't see much actual sprinkler use. Rather, it is ABS plastic, one brand name of which is Cycolac ("the football helmet plastic!") ~ Anyway, it is possible to create some built-in stress when the part is molded, not that you would ever know it if the part never takes a hit.


For my money, I would actually look at redesigning the PGP wiper seal. Patents have expired, and it would maybe be possible to "rip off" the Rainbird wiper seal.
I stand corrected.
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Old 07-24-2010, 02:45 PM
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Quote:
Originally Posted by Wet_Boots View Post
The hole in the cap was intended to accept the plastic diffuser screw, to "vandal-proof" the cover
The hole still allowed sand between the seal and the cap even with the diffuser screw in it...we tried that too. And I'm sure it never deterred a single vandal either!
They wanted us to repair the heads intially by replacing the wiper seals... then just told us to replace them.
I'm not sure why Hunter hasn't come up with a one piece wiper seal from a single material like Rain Bird's. Heck, the patent must be up on the 1800 series wiper seal by now?
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  #10  
Old 07-24-2010, 03:09 PM
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I remember a number of older systems with PGPs that all had fountains of water shooting from the cover holes, and there were even some homemade solutions, like plugging the holes with panhead screws.
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