No, the mixer is not defective. The numbers on the dial are for reference only, and not an actual calibrated scale. The Machinist Mixer uses a venturi to create a vacuum which draws the concentrate through the standpipe to then mix with the water. It does this using the water pressure on the incoming side. The concentration on the output side will depend upon your concentrate’s viscosity as well as your incoming water pressure.
You will need to verify the outcoming mixture with a refractometer, then make any necessary dial adjustments. To note, we recommend installing a pressure regulator on your water inlet if you have changing water pressures. This will ensure the correct output concentration, once set by the dial. It is also recommended to use the Mixer Lockout if operators are unaware of this, or if outright tampering is an issue.