Proper Membrane Housing Connection

[bowhunter]

For anyone building your own RO, please make sure you understand how to connect the membrane housing to the system. If you accidentally connect the sap and concentrate to the permeate connections and pressure up the system you will destroy the membrane by causing it to delaminate or worse. On all of the mid sized membrane housings I've seen the center post is the permeate and the connections on the sides (both ends) is for sap and concentrate. If you have any doubt ask the supplier.

[Bricklayer]

Great point, I blew a vessel apart last week when I installed a 3 way valve at the concentrate line. Figured it would be a good idea to be able to direct it either to the concentrate tank or the wash tank for circulating wash. What I didn't know was that I left it in the closed position. Unit ran for about 20 seconds and blew the PVC membrane housing all to hell. I'm lucky it was an old membrane I was using and I have a spare vessel. But lesson learned.

[Wanabe1972]

What kind of pumps are you guys running? My vessel is rated to 300 psi and a burst pressure over 600. You my want to think about a pressure relief valve. I have mine set at 290 and if for some reason that is met it just circulates back to the infeed side of the pump. Jeff

[wiam]

What do you have for a valve? I have a L 3 way on both concentrate and permeate side of my 900 gph. Switch them with machine running every time I use it. These valves are in black plastic pipe so if there was over pressure the line would blow not a vessel. I have had a line blow when it was froze but never from changing a valve.

[Bricklayer]

I was surprised too that it blew. My high pressure switch is set at 230 psi and have been running it at just above the cutout for as long as I've been testing it. High pressure switch never even tripped. I replaced the vessel and tested the switch and it works. My thought is that I was careless and had my RO in bypass mode. I have a switch to bypass the pressure switches just in case one malfunctions and I need to run the unit. I was scrambling around after it happened and was flicking all the switches off. so that's my theory. I have since rewired the switch to have it light up when it is pressure protected.
http://i1070.photobucket.com/albums/u495/bottenhof/Mobile%20Uploads/2017-01/FDED67EC-A229-48CC-AA02-35D9BD56108E_zpszpaxyh5p.jpg (http://s1070.photobucket.com/user/bottenhof/media/Mobile%20Uploads/2017-01/FDED67EC-A229-48CC-AA02-35D9BD56108E_zpszpaxyh5p.jpg.html)

http://i1070.photobucket.com/albums/u495/bottenhof/Mobile%20Uploads/2017-01/72209D1F-CE0E-404A-8E1C-D289FF410A09_zps3nrnjure.jpg (http://s1070.photobucket.com/user/bottenhof/media/Mobile%20Uploads/2017-01/72209D1F-CE0E-404A-8E1C-D289FF410A09_zps3nrnjure.jpg.html)

[Wanabe1972]

That doesn't look like much of a vessel. It looks like PVC with some caps on it. The vessels I'm using I believe are fiber glass or some other resin material. The caps push in and have steel keepers. It's lucky for you it was water that popped it and not air. You said this was a old used vessel. Could it have frozen at some point in its lifetime?

[Bricklayer]

It has the steel pins that go through. It's a lot thicker then regular PVC. I'm going to use it this year then get a new stainless vessel. The spare one I installed has a pressure rating on it of 225 psi. So I set my pressure switch a little lower.