[D.Salkeld_Ltd]

Been done before but can't find the posts.

What is the calculation to tell how long DI resin will last?

Thanks guys

[adixon]

5000000 divided by your tds

[jouk45]

hi david try this,       http://www.cleantech.co.uk/tdscalc.htm

Cleantech RO vs Di cost calculator 
           
 

[Paul Coleman]

5000000 divided by your tds

That's for 25 kilos isn't it?

[carlfoster]

Is that cleantech one accurate? If so, I've worked out that if you don't have a water meter, pure water only costs £5 per 1000 liters. I don't think this includes the costs of changing the membranes every 2 years though.

[JM123]

its 2000/tds = ltrs of water per litre of resin

eg
2000/10 = 200ltrs pure water from 1 litre of resin, so if I had an 11ltr vessel I should get 2200ltrs from it before it needs changed.

[Paul Coleman]

its 2000/tds = ltrs of water per litre of resin

eg
2000/10 = 200ltrs pure water from 1 litre of resin, so if I had an 11ltr vessel I should get 2200ltrs from it before it needs changed.

I think you are out by a factor of ten aren't you?
Shouldn't it be 20,000/TDS = ltrs per kilo of resin?

[adixon]

i do apologise lads its 500,000 1/2 a million divided by the tds got carried away with my zero's before

[edd]

well my tds before the ro is 2/ 3  and the resin seems to be going well Stu at skypoles said it could last easily 2 years it been ten months now who knows??

[carlfoster]

Ok, is it 500,000 or 2000, or 20000? Can someone actually accurately calculate this? I think I will experiment with my own system and work it out.

[freshwater]

All,

Its 20,000 parts per litre of resin, BUT tds is made up of positive & negative ions, AND resins are not normally 50/50 positive & negative.

So if your output is lets say all positive ions then your resin wont last for 20,000 parts it will only last for half of that at best.

BUT usually its a mix of positive & negative ions so use the 20,000 parts as an estimate, and if you get some where near it then you'r doing OK.

eg if your water is 10ppm then a litre of resin should process 20,000/10 litres of water = 2,000



steve@freshwatersystems.co.uk 

[Paul Coleman]

Ok, is it 500,000 or 2000, or 20000? Can someone actually accurately calculate this? I think I will experiment with my own system and work it out.

The 500,000/TDS gives you the number of litres of pure water per 25 kilo bag.
The 20,000/TDS gives you the number of litres per kilo of resin.
The 2,000 was an error.
As Freshwater says, it can vary a fair bit though.

[JM123]

sorry lads was out there, yeah sorry thats an error - it should be 20,000

hence 500,00(a bag = 25ltrs) = 20,000(a ltr)