Difference between marine watermarked and home reverse-osmosis systems

[ValiantV]

Originally Posted by SV THIRD DAY

Just to prevent a Cruise/Internet Rumor from being started, lets clarify this a bit.

A Sea Water RO unit CAN run in Fresh or brackish water as long as the water maker has the ability to dial down the system pressure. 800PSI is not needed in brackish or fresh water to reach the rated output of the unit, in fact taking the system to 800psi while operating in fresh water can damage the membrane.

Someone I know made a YouTube Video about this very issue...

I can see why 800 psi isn't required to produce rated capacity when operating in brackish or fresh water, but don't understand why it would damage the membrane.

The membrane has to be able to withstand that pressure anyway. Is it a matter of too many water molecules flying through the pores too quickly?

Just curious...

[SV THIRD DAY]

Originally Posted by ValiantV

I can see why 800 psi isn't required to produce rated capacity when operating in brackish or fresh water, but don't understand why it would damage the membrane.

The membrane has to be able to withstand that pressure anyway. Is it a matter of too many water molecules flying through the pores too quickly?

Just curious...

It's not about the Pressure...it's about the Flow.
Membranes are rated for a maximum "Flux" or flow through rate, so without the osmotic pressure of sea water holding the fresh water back from passing through the membrane too much flow (or Flux) will try to pass through the single molecular layer of active membrane film and will literally tear the microscopic pores as it rushes through.

You won't realize you damaged your membrane until the next time you go back to sea water and see your TDS through the roof due to the tears...new membrane time follows....

[ValiantV]

Originally Posted by SV THIRD DAY

It's not about the Pressure...it's about the Flow.
Membranes are rated for a maximum "Flux" or flow through rate, so without the osmotic pressure of sea water holding the fresh water back from passing through the membrane too much flow (or Flux) will try to pass through the single molecular layer of active membrane film and will literally tear the microscopic pores as it rushes through.

You won't realize you damaged your membrane until the next time you go back to sea water and see your TDS through the roof due to the tears...new membrane time follows....

Makes perfect sense.

Thanks!

[UNCIVILIZED]

Somewhere in this conversation, off in the background you'd heare Dr. McCoy utter the words "Green blooded freak".

[ValiantV]

Originally Posted by UNCIVILIZED

Somewhere in this conversation, off in the background you'd heare Dr. McCoy utter the words "Green blooded freak".

Fascinating....

[Crown Royal]

Great explanation.