TLDR;
1) Is it possible that 20% lower HP
pump RPM can cause higher PPM? From 200 to 1000?
2) Do some new membranes have lower quality?
3) Can you shot a membrane by running it at high pressure (1000psi)?
I have a Desallator
watermaker. After only 1 year of usage its
brushes were gone. Manufacturer asked $200 for
brushes only. I said **** off to them and bought an 220V
engine for $200. The main difference is that it has 20% lower
RPM.
Also at some point for 1-2hours membranes were at abnormal pressure. Probably >1000psi.
I checked PPM and it was 1000ppm. I decided that due to my mistake I shot the membranes and need to buy new ones.
I bought new ones from Amazon for half the
price, no brand name but "made in USA".
After assembling I checked PPM and it became 2500!
The membranes on Amazon have few
reviews and apparently people were happy with them.
In one the threads here I read that a lower RPM can cause higher PPM. I made a different pulley so the
pump RPM is now 20% more then originally was designed. PPM lowered to 1200 but still too high.