Pressure Difference Before & After Micron Filter

Assumption: 10" 5 micron filter

I'm finishing up a homebuild RO system and want to better understand what to expect concerning a pressure change from the feed inlet to the 10" 5 micron filter and from the filter to the high pressure pump. I assume that with a new and clean filter the pressure readings won't be significantly different. However, as the filter does its job and becomes clogged, what should I expect for a pressure delta between the infeed and outfeed ports of the filter canister?

The system is currently programmed to shut off if pressure drops below 30 psi on the outfeed side of the filter. I have no idea what to expect for a pressure build up on the low pressure (infeed) side of the filter as it becomes clogged. Will it go above 50 psi and still provide a 30 psi outflow? Will it need to go higher? The low pressure pump has a max psi of 75.

Thanks in advance for any information.

Haynes

Your pre-filter or sediment filter can tear apart if the pressure drop gets too high. When you start with a clean filter the pressure in and out will be about the same. The longer you run the lower the pressure out of the filter will be relative to the inlet pressure. I would recommend that you change out the filter element at 15 psi of pressure drop so that you never have to worry about damaging the filter. If the pre-filter breaks apart you can damage the high pressure pump and potentially the membrane or membrane housing.

Thanks, Bowhunter.

Based upon the 15 psi differential, I'll set my low pressure switch (outlet side of filter) to 35 psi. It's feeding a Procon that has a minimum requirement of 30 PSI, so it should protect the high pressure pump. On the feed pump, I'll swap the factory pressure switch for one with a low (20 psi) and high (50 psi) cut off, so as the filter clogs and the pressure is inversely related, the pumps and filter are protected.

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Originally Posted by Cloverland Maple

Assumption: 10" 5 micron filter

I'm finishing up a homebuild RO system and want to better understand what to expect concerning a pressure change from the feed inlet to the 10" 5 micron filter and from the filter to the high pressure pump. I assume that with a new and clean filter the pressure readings won't be significantly different. However, as the filter does its job and becomes clogged, what should I expect for a pressure delta between the infeed and outfeed ports of the filter canister?

The system is currently programmed to shut off if pressure drops below 30 psi on the outfeed side of the filter. I have no idea what to expect for a pressure build up on the low pressure (infeed) side of the filter as it becomes clogged. Will it go above 50 psi and still provide a 30 psi outflow? Will it need to go higher? The low pressure pump has a max psi of 75.

Thanks in advance for any information.

Haynes

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As bowhunter said, it will implode and tear stuff up! It happened to me this year. I upgraded my deer run 125 from gas motor 100 gph pump to an electric motor and 330 gph procon. I did not upgrade the 10x2.5 filter system and when that element came apart- it went trough the procon making a racket, and parts of the filter hit the membrane vessel and popped the bottom off, breaking the permeate tube on a brand new membrane. This was my first run of the season and I had to order a new Procon, a new membrane, and a 20x4.5 filter. I'm feeding the Procon with a Wayne 1 HP pump. I will have a LP gauge and safety switches put in for next year. The 2.5x10 elements are rated to 5 gpm, the 20x4.5 are 15 gpm.

Yikes! Sorry to hear about the misfortune. I have a similar set up with a ProCon 330gph pump fed by a 3/4 hp Flotech. The filters have a flow rate of 10gpm. I didn't want a feed pump that would push more than the filter could handle. I made the assumption that a higher flow to the filter than what the filter is rated would increase pressure on the inlet side of the filter.

Do you have any pressure switches on the Wayne pump? How are you protecting that pump from low/stopped infeed or from pressure build up on the discharge side? Curious to know as this my last problem to solve before the wiring is underway. (I may have to discard the external pressure switch that came with the pump and wire in another low and high pressure switch - but that would make 4 total pressure switches on the system, which seems excessive). Thanks.