Cut-Down Pressure Valve
The purpose of the booster pump is to increase water pressure going into the R.O. System. The working pressure of RO Membrane is about 5-6 kg/cm2 (70-80 psi), so we have to use booster pump to increase pressure. Every 10 meters of height can produce 1kg / cm2 (14.22 psi) of water pressure.
If your water pressure is 6 kg/cm2 (80psi), it's enough to run R.O. System nicely and do not need a booster pump. Conversely, if the inlet pressure is higher than the above values, you need to install the Cut-Down Pressure Valve, in order to avoid over pressure, causing filter housing or pipe burst.