Pump motor size

[MunsterMapler]

I have been doing a lot of research on here, and plan on starting my 4x40 ro build. I'm planning on a 330 procon but can't decide what hp motor to get. I'm gonna start out with 1 membrane but want enough motor to expand in the future to run a second. My question is will a 3/4 hp motor and a 330 procon be enough to run 2 4x40 membranes? Or do you guys think I would be better off with a 1 or 2 hp motor?

[nymapleguy607]

Check the specs out on some of the commercially available hobby size Ro's. I don't know the pump model but my RO uses a 1hp motor on the High pressure pump pushing through 3 membranes, however mine is also running a recirculation pump. Check out the Next Gen maple ROs.

[Clinkis]

When I purchased my 330 procon pump from a procon dealer and told him what I was doing with it he said minimum 1.5hp. I ended up going with 2 hp. Price difference was minimal and motor doesn’t have to work as hard, produces less heat and thus should last longer. I’m running 2 membranes in series with it and am very happy with its performance so far.

[mkoehler79]

You will want a 1.5 HP motor if you plan to run the pressure up over 200 psi. The number of membranes doesn't matter in sizing the motor.

[MunsterMapler]

Awesome, thanks for the help guys. I was kind of planning on getting a 2 hp motor but was wondering if it would be ok to go smaller. The extra 75 buck or so will probably be better in the long run

[halladaymaple]

Hi

I use a marathon 1.5 hp 220v to run my 2 4x40 MES membranes my feed pump gets to 50psi. Runs no problem at all. I also have a SS 330 gph procon pump. 2np will obviously work fine for you

Good luck
Darrell

[MunsterMapler]

Another question I have is what types of pressures are on the outlet side of the membrane? Trying to look for some flowmeters but can't find any pressure ratings on the website. Also is anyone running a flowmeter on there recirculation loop to know how much they are sending back to the membrane?

[Clinkis]

I run my pressure between 225-275 psi. I have a HP switch that cuts out at around 290 psi to protect things. Yes I have a flow meter on my recirculation loop. All my flow meters are 0-10 GPM. They should all be after the needle valves so pressure shouldn't be an issue.

[MunsterMapler]

Good point didn't quite think that one one through. Do you think a .5-5 flow meter will be adequate? Planning on a .1-1 for concentrate and .2-2 for permeate.

[Clinkis]

I’d say 0-5 minimum for all. 0 to 10 be best for concentrate. The pump runs at 5.5 GPM. If you add a 2nd membrane your permeate flow will be over 2 GPM. It also makes them a lot easier to read if you have the flows near the middle of the gauges then right at the top so a little bigger is better for the flow gauges. I made the mistake on my last RO of undersizing my flow meters and they were hard to read or would go off the scale sometime.