ProCon (vane) vs Gould (multistage) Pumps for RO

[Cloverland Maple]

Several posts on MT suggest users are using ProCon pumps, particularly 330gph for multiple membranes (series or parallel) However, I have not seen much discussion on higher output ProCons or similar rotary vane pumps, such as those that do 600+gph. I understand the higher output ProCons become expensive and may be cost prohibitive.

Application:

Several designs are being considered, but let's assume I'm building an RO with two 4x40 XLE4040 in series. A 330-360 gph rotary vane pump has been suggested, although that is only a positive displacement of 5.5-6gpm. The 4x40 XLE membranes indicate a max flow of 14ish gpm. It seems that a higher output would be more efficient and decrease the chances of fouling. I want to be practical in this build, but don't necessarily want to shy away from using a better product or method, if one exists.

The cost of the ProCon 330, adapter and 1.5 hp Leeson motor is nearly the cost of a multistage Goulds 7 or 10GB (eBay). I'm having an internal debate on the better method, as each has it's selling points. I have a couple specific questions, but also seek any other relevant input. THANK YOU.

Question 1: Is there a particular reason higher output ProCon (or equivalent) pumps aren't being used? (E.g. 600ish gph vs the 330gph rotary vane)

Question 2: If there is a desire to have higher output (more than 5.5gpm which is a ProCon 330gph pump), are users opting to use a multistage pump instead?

Question 2b: If using a multistage pump, what temperature does the sap enter the membrane after going through the pump?

[Greg MacWilliam]

Last year I built a ro using 2 4x40 mes filters and a 600 gph procon pump with a 2 hp motor. It works very well and would give me 50 gal of 8 percent for 5 hours before cleaning. This year I am adding a 3rd filter and another 600 gph set up. These pumps are pricy but work great

[Bricklayer]

I have a multi stage pump on mine. Weber webtrol. Similar to the goulds multistage. It is rated at 600 gph.
The temperature doesn't change on a multistage with sap entering the membrane. It only heats the sap up when you circulate it. Say in a wash cycle. Has no effect on sap temp while running RO concentrating sap.

[Cloverland Maple]

Were you running these in a series or in parallel?

[Cloverland Maple]

I don't know much about the Weber Webtrol. Are you satisfied with its performance?

[Cloverland Maple]

These pumps are pricy but work great

It's kinda why I am also asking the questions. I can get a Goulds 10GBS10 for rougly $600. The ProCon 600 is only a few bucks less and without the adapter and 2PH motor, all additional cost to me since I don't have them sitting around. Is the extra money for a ProCon set up worth it, or should one look at the multistage.

[mkoehler79]

Be sure to consider the pump pressure/flow curve when selecting the multi stage pump. Multi stage pumps are not positive displacement so when pressure goes up flow goes considerably down. Procons are positive displacement pumps so the curve is more flat regarding flow at higher pressure. I used a procon to create the pressure and a dayton multistage to circulate max flow through the membranes. The Dayton pump I selected has a Max case pressure of 300 psi so it handles a circulation loop on the high pressure side of the procon. Less fouling is seen at Max membrane flow. FYI...see Zoro tools website for Dayton pumps...they often have 20% plus flash sales to save money if you subscribe to emails.

[Cloverland Maple]

I found the multistage pump flow curve to be the downside of using such a pump. But if I understand you correctly, the ProCon is pushing the feed, at the desired pressure, to the multistage, then to the membranes? Do you also have a feed pump for the ProCon?

[mkoehler79]

17022 Here is a diagram of how I plumbed the RO. And a picture...17023

[Cloverland Maple]

Thanks. Nice looking unit. I'm assuming you had head pressure from the sap tank to feed the HP ProCon pump?

[mkoehler79]

Yes head pressure from the tank and sap filtered prior to going into tank to eliminate the potential for any chunks going through procon. A feed pump could still be used and may be advised, but powering the unit from a generator was my deciding factor in the configuration.

[Bricklayer]

When I was figuring out the pump curve for mine to see how many membranes it was good for I contacted weber.
I told them I was feeding the pump with 60 psi feed pump and they explained to me that their curve charts are at 0psi. So if you feed at 60 psi you take 60 psi off your desired flow rate at that psi. So if your looking at 200 psi then you look at the 140 psi flow rates on the pump curve.
I have my 1 membrane fed with a 3/4" and I can't get the pressure below 140 psi even with the recirc open and the concentrate valve wide open. And flow gauges say I'm doing 9 gpm across membranes. So I'm going to add a membrane this year in parallel to bring initial pressure down. If the pump can't keep up I will put it in series.

[Greg MacWilliam]

The procon 600 needs a positive feed pressure of at least 20 psi. I plumbed the filters in parallel and ran a return line to the intake side of the procon. The second procon will be for high pressure re circulation. Bought the motor from Harbor Freight mainly for price but it ran well.

[mkoehler79]

I would recommend adding the second membrane in series to keep your flow high through the membranes. As far as the pressure not dropping, I would look at going to a larger size concentrate valve since restriction of flow is what creates pressure. Just my two cents.

[mkoehler79]

The procon 600 needs a positive feed pressure of at least 20 psi.
Absolutely required for the larger procons!

[Cloverland Maple]

I have my 1 membrane fed with a 3/4" and I can't get the pressure below 140 psi even with the recirc open and the concentrate valve wide open.

This cause any issues when you were in wash cycle?