Question
I am looking for different types of internal mix polyester spray equipment.
I am currently using a Graco that has been modified by our equipment supplier and has a small slave pump for the MEKP. The main pump contains the base mixed with cobalt and reducer and the slave pump carries the MEKP. The ratio for mixing the material is based on the amount of pressure from the slave pump. We also have an alarm system that goes off when the pressure jumps too high or falls too low. This is an internal mix system with a mix manifold in the booth with a flush system.
All in all the system is adequate, but sometimes parts don't cure properly, so this leaves a lot of room for error. We also have to repair the pumps more frequently due to the material being used. The material is heavily pigmented and wreaks havoc on our packings on the base side of the pump. I have never before seen a Graco needing to be rebuilt this much.
Any suggestions on how to improve this system (or replace it)?
Forum Responses
Sounds like your MEKP pump is out of ratio enough to slow the cure on some parts. Most of the pumps I have worked with are 1:1 ratio with a flush pump also. One side has one half of the reducer and all the cobalt and the other side has all the MEKP and the other half of the reducer. Then at the manifold it all comes together. Most of these types of pumps are diaphragm pumps and don’t need to be rebuilt very often at all.
One thing Graco doesn’t tell you is that their stainless piston is fairly soft and wears. You need to get hard chromed stainless--this will last much longer. Have your company call in a rep to demo some other pumps.
Bob Niemeyer, forum technical advisor
