Lagoon Duo 100 desalinator

[Snowandsail]

Hello all, I have a 2020 lagoon 46 with a Duo 100 Desalinator and I’m trying to inspect and replace the membrane seals. The problem I’m having is I cannot get the end caps off of the pressure vessel for the membrane. I have tried using a vice like the manufacture recommends but I have not been able to get it to move at all. If anyone knows the trick to this please let me know. Thank you.

[Tellie]

The dangerous way is to use compressed air. Block one of the high pressure in or out fittings on the membrane and use an air compressor line on the open one. "DO NOT!!!", I repeat "DO NOT!!!" stand in front of the end of the membrane vessel that is blocked off. We throw a heavy moving blanket over membrane vessel end that give us fits to not only catch the end cap but to slow down the membrane that is now coming out at mortor round speed. Most membrane vessels can handle up to 2,000psi. Most air compressors don't make that much pressure but there is a lot of volume in a membrane vessel and when that end cap lets go the membrane comes with it.

[ItDepends]

Air pressure, do not! Dangerous and stupid. But WATER pressure works a treat. Safe and easy. Way easier than the desalinator “official” method.

A method for removal of the membrane end caps that is a likely to be a bit more gentle to the parts is to attach a fresh water pressure water hose to the salt water inlet, fill the housing with water until it overflows from the brine outlet, then block the outlet with your finger. Even a little pressure, and the caps just slide right off.

[Snowandsail]

Yea I tried using water, even with the hose at full pressure to the point where I could hardly hold the cork plug I made for the outlet, neither end cap budged a bit. I ended up using a vice and two sets of very large channel locks with two people pulling against each other while twisting off the end cap. Not typical tools most small cruising boats have so I was lucky to have a super yacht with a kind engineer to help me in their shop space.

In the end, we got the caps off, but they now look like they have been chewed up by a pit bull. I got the new membrane in, and it all works, but I still cannot believe that Dessalator would design something so stupid. I would never buy this system for my boat as long as it is this difficult to replace a membrane. A system should be serviceable, or it is poorly designed.