Ro Unit

[orange shark]

Hi,

i've recently bought an RO unit and it has been set up for 2 weeks now. The first week and a half i measured the TDS at around 4, but i checked today and it was abover 40ppm.

I have ball valves on the input and output of the unit so i can switch them off when i dont need to use the unit and keep water in there so i cant see how the membrane is damaged, the only thing i can think of is that i flushed the unit for around 45 mins today (forgot it was flushing), does over flushing damage the membrane?

Thanks,

orange shark

 

[The-Wolf]

like anything that is mass produced, it is possible it is a manufacturing fault,
I doubt that overflushing did any damage.
phone the place you purchased it from and see what they are willing to do for you.

remember that under the sale of goods act
any item you buy 'has to be fit for purpose'
and a faulty membrane defiantly makes the item unfit.

 

[rabbut]

The only solution I can offer is that the mambrane has gone. What is the pressure to the membrane, and into the unit, and is the flow from the use pipe as good as normal?

 

[orange shark]

can i continue using it for water changes until i get a replacement?

the mains pressure was 100ppm

 

[rabbut]

Will be better than tap water if that has a hardness of 100ppm.

What is the mains pressure (in BAR or PSI)?
What is the pressue to the membrane?
Is the units output any different flow-wise?

All the best
Rabbut

 

[orange shark]

sorry meant pressure was 100psi not ppm

i dont know what the pressure is to the membrane and no the output is the same as always

 

[SkiFletch]

There is no harm in over-flushing, that much I can assure you

There are 4 ways a membrane goes bad:

- Years of use (not your problem for sure)
- Exposure to Chlorine, Chloramine, or Bromine (does your RO unit have a carbon pre-filter hooked up? If so, that removes those problems)
- Overheating (did you push hot water through the membrane?)
- Drying out (sounds like yours didn't with appropriate ball valves to keep it wet)

 

[orange shark]

if the prefilter is one of those rings at the bottom then yes
no hot water goes through it
so my ball valves didnt work? as soon as i turn the valve on, on the input the mains pressure goes to 0 and when i turn the other it stops flowing so it seems like they work. I think my main problem may have been i switched the input one off first then the output but i didnt think this would make much difference as they were getting turned off within 5 seconds of each other

looks like im going to buy a new membrane after 2 weeks

 

[SkiFletch]

Oh sorry, I never finished my post

Your ball valves probably worked, especially on a brand new unit. Since none of the above seemed to be the problem, it's most likely a manufacturing defect. I'd contact whomever sold it to you, voice your displeasure and get it replaced, RO membranes don't fail that fast

 

[orange shark]

thanks, got the afternoon off tommorow so i shall do it then among the other jobs!

would it be safe to use while waiting for another membrane?

thanks,

orange shark

 

[SkiFletch]

40ppm is still probably better than the 400 ppm coming out of your tapwater...

 

[rabbut]

I'd contact whomever sold it to you, voice your displeasure and get it replaced, RO membranes don't fail that fast

Oh but they can The unit at work had it's membranes go after a month of use. The supply valve had jamed half on after heavy rain and this appeared to glaze them over somehow. The boss wasn't happy, the membranes for an Osmotics Merlin 200gpd unit apparently aren't cheap....

I also remember my ex-supervisor mentioning that constantly pressurising and de-pressuising units lead to premature membrane failure, though it should not take that little time. He worked with them apparently for most of his working life in the drinks industory, so I trust him to know his stuff there. When you stop a unit, you should close the use valve first, then the waste and finaly the supply to keep the membrane under pressure Also, get a pressure guage between the last pre-filter and the membrane to make sure the pre-filters are changed just after flow starts to reduce, to avoid membrane glazing...

I'm feeling lucky today, I usualy get slated rather quickly when I contradict a mod, as I'm usually wrong..... *braces for strong return argument against pressurisation-depressurisation harming membranes along with slow flow through them...*

All the best
Rabbut

 

[SkiFletch]

Well, remember, a faulty supply valve isn't a faulty membrane

Feel free to contraict, I'm always learning too. Interestingly enough, my own membrane is now 3 years old constantly pressurized/depressurized and it still works great... Not sure what that means other than that these are pretty complex problems with a bunch of points of failure

 

[orange shark]

rang ro man today and they didnt pick up, the auto machine thing told me to email so i have done with no reply yet

 

[orange shark]

feel right daft now...the water i tested was left with a lid off for around a week

just tested new water that was pumped out today and it measured 1ppm