Air bleeder valve

[Bricklayer]

Where is the best location to install a valve to bleed the air from an RO ?
I have a single 4x40" membrane. Vertical mounted, inlet is on top and permeate, concentrate at bottom.
I was thinking of using a T at the feed inlet of membrane and installing a ball valve with a tube going to a drain. Kinda the same looking setup as a pressure relief valve on a hot water tank. If I crack it open a little bit while starting the LP pump it should let any air escape. Then before starting hp pump close it. Anybody else do something similar?

[madmapler]

I really don't think a bleeder is necessary unless maybe you want to fill them to soak or something like that. They should just purge out with the start of the pressure pump.

[Bricklayer]

That's what I thought, but I have read a couple posts on here that some of the pre filters have air release buttons on them to let air out. Mine is a big blue 10" and it dosnt have the button on it. So I though it might be a good idea to have one. I am going to have a valve at the t at the concentrate outlets and permeate outlets at bottom of membrane to drain entire system if needed.

[Clinkis]

It's not necessary. System will bleed out on its own.

[Bricklayer]

I have a Weber multistage high pressure pump. Will my low pressure pump running at 60 psi push water through it when it's not running? I haven't been able to start it all up yet as I'm waiting for a couple parts. I hav a couple old 4x40 membranes that I'm going to test it out on but should I put a bypass that just feeds the membrane with the lp pump to bleed air out? I know some of the deer run maple RO's have this feature.

[maple flats]

My Deer Run LP pump pushes the sap to and thru the HP pump, but I turn on the HP pump as soon as I have over 20 PSI on the gauge just after the pre-filter housing. If the pressure drops to zero I shut off the HP pump a few seconds and then back on. It just needs to get the sap to the HP pump. A bleeder might help this, but it is not necessary.

[Bricklayer]

I just got my Weber pump back from getting a new set of fresh seals. So I'm gonna hook it back up and see if my lp pump pushes water through it. Hopefully it does. LP pump pushes 65 psi so I'm sure it will be enough to go through hp pump. If I put my fingers in the outlet hole and I can turn the veins no problem. Not much resistance.

[BreezyHill]

I would recommend reading the MES lit on ROs and some of the DOW pdf files about cleaning membranes. DOW told me it is best to wash the MBs at as low of a pressure as possible to get the best affect of the cleansers and to flush the dissolved material away. Also to clean the MBs parallel and not in series to keep cleaned material from laying into another MB if it is not full dissolved. MY High Pressure pump is above the recommended 20-30 psi the tech recommended so I only use my supply pump and have had the best cleaning results by following this recommendation.

So a by pass for the high pressure pump, keeping the corrosive fluid away from the pump seems to have some merit.

Another suggestion I have been following was to have a filter that is for cleaning cycles and use it for three cycles and discard unless it is visibly contaminated then discard sooner. No reason to use a new filter each time and never use the one from running sap due to the amount of cleanser that will be used on the filter.

[Bricklayer]

I just bought 2 boxes of 12 x 5 micron filters. They accidentally sent me 2 boxes of 10 micron pleated filters the first time. They told me to keep them. I was planning on using these filters for cleaning. It's just permeate going through so 10 micron should do? I gotta use them somewhere

How would the by pass be plumbed? I would assume a check valve would be needed to keep the flow from going into the output of hp pump?

Just kinda answered my own question.... A 3 way valve would work best.

[BreezyHill]

LOL, isn't it funny how we already know the answer to our own questions so much of the time. Those valves are pretty reasonable on ebay now.

[Bricklayer]

Yup.
Going to order one today.
I do have one more question about air in the system
I have 1/4" O.D lines going to both my pressure switches and filter in/ filter out and one for the main operating pressure. When I prime the system for the first time do I need to unscrew the ends to get the air out of these lines so it's not full of air or will that air move its way out also.?

[Bricklayer]

Did a full test of my RO today and found a few leaks. But the major problem was my big blue filter keeps air locking. It's not sucking air from anywhere the feed tank is full and pump is fully primed. If I shut unit off in a few seconds it bubbles in the feed tank and unit is air locked. If I unscrew the filter and bleed it out it fires up and pumps fine. I've tried taking the 5 micron filter out and just running it with the casing but it still locks when I shut it down. Anybody else have this problem?

[Wanabe1972]

My filter is not the big blue but the same size and is clear. The top has a red button built in for bleeding air out. I used this the first few times i ran it but then realized after just a few seconds of the filter running half full it would fill up. I have never had to bleed the sytem. My Feed pump starts up and brings the pressure of the system to 30 psi and the High pressure pump starts automatic once this pressure is reached. This way i use my low pressure pump for multiple functions. The only way the high pressure pump starts up is if the valve is opened to send sap to it and pressure reaches 30 psi.

[Bricklayer]

I forgot to add that my hp pump is not running. The pressure switch will not let it come on unless it has 40 psi. I seem to be getting a siphon effect when the system shuts down. I might try and get a filter with an air release.

[Bricklayer]

I changed the o-ring on the big blue filter and it kept it from locking. Must of been sucking air somehow.
That problem is solved
Was able to test it with hp pump running now that it doesn't lock up and just have 1 stubborn leak at the hp gauge where the copper tubing connects to the gauge with a compression fitting. Slow slow drip. I have been looking for 1/4" braided stainless to replace the copper tubes but can't seem to find any that would suit. Only places that seem to sell them are auto parts stores. And I'm sure they aren't food grade.

[Bricklayer]

How would I plumb in a bypass 3 way valve for cleaning and rinsing purposes. I seem to lose a lot of pressure and flow when my lp pump has to push water through the hp pump. So basically it would tee into my 1" hose coming from my big blue filter that feeds my hp pump and bypass the hp pump and go directly to the membrane. I realize a 3 way valve would be needed but configured how?