Gun won't spray upside down

C

curt b

Anyone ever had a gun using pps cups that won't spray upside down. It will spray every other way but will stop a start back sometimes and the pps cup swells up? It's a Iwata lph 400 and does it with the purple and silver cap. I take it apart after every time I paint. What am I missing, did I damage something. I have had the gun a little over two years. These are the small cups I haven't tried the quart ones lagain.
 
Sounds like you got a leak in the cup. It will only spray upside down if everything is perfectly sealed. When it is sealed correctly the air inside the cup is slightly pressurized allowing you to spray upside down.
 
Makes sense but with pps cups every one is new. I have tried several different ones and did the same thing. I even got a new cup and cap. I'll look at it again I have got to be overlooking it. Thanks.
 
When you fill a pps cup and put it on the gun, the first thing you are supposed to do is turn the gun upside down and fully pull the trigger until all the air is out of the bag and the gun starts to shoot paint.

I have never had a problem with the lph 400 using the pps system.

The only thing that comes to mind is you have very low air pressure at the gun or very low air flow at the gun or both?
There needs to be enough suction created (low pressure area) across the guns venturi to pull the paint out of the cup when inverted.

If it will pull the air out and then paint when first filled as I mention above there is no reason for it to know work.
I have never had my pps cup bulge or indicate any pressure being introduced into it.

I do not think a properly working gravity gun will pressurize the cup, if it did then when using a standard cup there would be air bubbles appearing in the paint in the cup as the lid on the standard cup is vented. If that vent gets plugged the gun wont spray properly.
 
I have never purged or turned a gun upside down before spraying and have never had a problem. I found the problem, apparently it was a bad batch of liners. The lip on three of them out of the whole box had a crease in them, musta have been a boo boo in making or somewhere. Anyway opened a new box and they work fine so apparently just my luck again.
 
curt b;n76138 said:
I have never purged or turned a gun upside down before spraying and have never had a problem.
Click to expand...
How can a cup with air in it spray when upside down? The air is at the top of the cup at that point and paint will not come out until the air is purged.
I guess 3M doesnt know what they are talking about:

[video]https://youtu.be/CIC2fuUAP4E?t=2m45s[/video]
 
I have never turned a gun upside down before spraying. Found the problem, fixed the problem, thanks for the advice.
 
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