Re: Graco Proshot cordless airless
I talked to Graco technical support yesterday, and they helped explain a little better how this machine works. The instructions aren't real clear about what the purpose is of this valve on the side- it sounds like something to relieve the pressure before removing the cup.
However, they explained to me that this is to "prime" the pump. You need to get material circulating from the cup to the gun and back to the cup first. That takes about 10 seconds of holding the trigger with the valve open. You then shut the valve, and the material flows to the tip rather than all back to the cup. If the pump loses prime for any reason, like you tip the cup too much and get air in, you need to re-prime. You can also lose prime if the check valve opens because of a clog or piece of dirt, or if the check valve opens because the material is too thick.
I tried more spraying today, and now that I understand it, it is working better. Maybe all these types of airless guns work like this, requiring priming, and everyone knows this, but this is my first experience with airless, so I didn't get it.
I talked to Graco technical support yesterday, and they helped explain a little better how this machine works. The instructions aren't real clear about what the purpose is of this valve on the side- it sounds like something to relieve the pressure before removing the cup.
However, they explained to me that this is to "prime" the pump. You need to get material circulating from the cup to the gun and back to the cup first. That takes about 10 seconds of holding the trigger with the valve open. You then shut the valve, and the material flows to the tip rather than all back to the cup. If the pump loses prime for any reason, like you tip the cup too much and get air in, you need to re-prime. You can also lose prime if the check valve opens because of a clog or piece of dirt, or if the check valve opens because the material is too thick.
I tried more spraying today, and now that I understand it, it is working better. Maybe all these types of airless guns work like this, requiring priming, and everyone knows this, but this is my first experience with airless, so I didn't get it.
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