Reverse osmosis line pressure, is it measure pre or post filters.

[Slipstream06]

I have a ro/di and I believe recommended line pressure is 50 for a 75 gpd membrane with an additional 75 membrane purchased fromy brs. Is the line pressure measured after the pre filters or post filters prior to the membranes? Line pressure before pre filters is 50 lbs and after pre filters 40 lbs. Is this enough pressure or should I look into a booster pump?

 

[firemountain]

You want to measure the pressure going into the membrane.

I am a bit confused from your post....please clarify.....Are you running two 75 Gpd membranes, or just one 75 Gpd membrane on this unit? If so...you will definitely need a booster pump.

40 psi going into the membrane is too low.