Help with non-functional NEW 3M PPS System

[Alan Lightstone]

Being driven crazy by this one. I bought a 3M PPS system (to go with my Fuji XPS gun. It came with the appropriate sized adapter (#18 for my Fuji bottom feed gun). I screwed on the adapter, finally got it tight enough, and tried to use it.

The system works great with the small pressure cups (6 ounce size).

The problem lies with the large bottom feed liners (24-25 Ounces) and cups. When I pour solution into the cups, close them up and start spraying the gun first eliminates the air in the cups (as I believe it is supposed to), then sprays for a while while the liner scrunches up. If I release the trigger (as you obviously do multiple times while spraying), the liner no longer empties, and the gun won't spray any longer.

Now there's something weird about the liners too. They don't extend down to the bottom of the cup. They stop a few ounces short of there, almost like they are the wrong sized liners for the cup. They fit at most 20 ounces of liquid, yet the measuring scales on the liner insert and the cup itself is supposed to hold 28 ounces. The invoice from the purchase says that the lids and liners are 24-25 ounces, but I'm thinking it's really the large 28 ounce size:
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When I check the liners after this, they have linear cuts in them, so are leaking air (or fluid from the liner), so they do not pressurize.

Any clue what is going on?

Are these the wrong sized liners for the cup? It looks to me like I was sent the standard size liners for the large size cup. Could that be the reason for my difficulties?

[Peter Froh]

Those are the wrong sized liners. There are three sizes for the PPS system if memory serves me correct. Only the large size and small size work on an HVLP gun. The liner should rest on the bottom of your cup.

[Bruce Hand]

Hello Alan yes they are the wrongs liners but as I have found they also will work no problem. Were there cuts on the liners before you installed? The inside of cup is smooth so can't see how they could get damaged.
I always found the large liners full of paint was tough on the wrist after a while

As always make sure the pressure tube to the cup is not blocked and make sure the liner seal fits perfect on the cup before you install the lid, spin it around on the lip to make sure and make sure the ring is on tight

Can you take some photos of the cuts?

Bruce

[Alan Lightstone]

I'll see if they haven't been thrown out, and I'll take a picture.

Interestingly, I purchased some large size liners, and they work just fine. But the standard size liners have failed 100% of the time.