I was out today on my Duotone Unit 5.5 2022 when I noticed the wing starting to lose pressure.
While packing up I noticed the clear O-Ring in the dump valve was partially unseated.
This is the second time I have had this issue. My 6.5 Unit had the same problem and I could not reseat the O Ring so I wrapped some plumbers tape around the male dump valve cap and did not open the dump valve again when deflating the wing.
Anyone else have the same issue?
I'm lazy and couldn't be bothered with the little Velcro tabs, so just deflate via the inflation valve. Looking at your pic, glad I do it my way.
I honestly don't know why manufacturers put dump valves on wings, maybe on wings bigger than 5m but I still wouldn't use them. Just adds weight, points of failure and extra hassle when repairing a bladder.
I try to use the dump valves as little as possible. Had one leak on the leading edge and got my wing repairer to patch over the valve completely.
Well that's interesting. I've had a lot of duotone wings and none of them have shown this fault. Good to know tho. And nice work with the plumbers tape for a fix.
I use the dump valve on the newer slicks and units because it's located on the wing tip and makes deflation and rolling up the wing heaps easier. I have heard the inflation valve can become compromised if you use it to deflate - but I've not experienced this myself for the few times I've done this.
Yes, have the same issue with one valve. After frequent use over 1,5yr. Will either need to close it permanently or change the bladder. the other valve was getting a small tear on the lip and I stopped using it. I used them year around also in cold freezing temperatures.
bit of a shame. Dump valves work great. Not being able to use them will be a nuisance, but can live with it
still love my 5.5 Dlab and also use my 4m unit v1 (no issues, but used it less frequently)
From the kitesurfing days I had similar problems with the Duotone dump valve after repeated pulling on and off. Have ripped the tab and damage the O-ring. Duotone had good intentions with ease of packing but unfortunately the team riders only use for short term so they don't know the wear and tear over a year or 2 of ownership. I have complained to the local shop. I never use the Duotone dump valves for that reason. First time closing the dump valve is the last time I will touch the valve. My advice is deflate the airport valve and wait few minutes to air out then do the roll up. No big deal as I really like the Units.
Longtime duotone (north back in the days as well) user here both kites and wings - I think the valves are the most stupid things in their line ups. Both airport valve but especially the dump valve - wtf duotone???
Love the dump valves, live in Perth, wing heaps, never had an issue, can't imagine not having a wing tip valve, the ease of packing is so good, also the inflate valve is one of the best, just bloody annoying that they don't include an adapter for it when you buy a wing
I've never had a problem with the pathetic dump valve as I've never used it.
I pack up in a method developed by BRM Cloud Maui which simplifies everything. 
Good to know about the dump valve.
I like the duotone air port valve. But my newest wing the air port valve does leak some without the cap on.
I've found the adapter from PKS is made better (better fit and material) than the one that Duotone sells.
"PKS PUMP ADAPTER FOR DUOTONE AND CORE."
They wear pretty quick, just glue it up and don't use it again