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UK Window Cleaning Forum => Window Cleaning Forum => Topic started by: D.Salkeld_Ltd on November 28, 2006, 08:19:35 am

Title: DI Calculations?
Post by: D.Salkeld_Ltd on November 28, 2006, 08:19:35 am

Been done before but can't find the posts.

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

Thanks guys

Title: Re: DI Calculations?
Post by: adixon on November 28, 2006, 08:31:08 am

5000000 divided by your tds

Title: Re: DI Calculations?
Post by: jouk45 on November 28, 2006, 01:44:19 pm

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

Cleantech RO vs Di cost calculator 
           
 

Title: Re: DI Calculations?
Post by: Paul Coleman on November 28, 2006, 02:21:54 pm

Quote from: adixon on November 28, 2006, 08:31:08 am

5000000 divided by your tds

That's for 25 kilos isn't it?

Title: Re: DI Calculations?
Post by: carlfoster on November 28, 2006, 02:25:07 pm

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.

Title: Re: DI Calculations?
Post by: JM123 on November 28, 2006, 06:04:47 pm

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.

Title: Re: DI Calculations?
Post by: Paul Coleman on November 28, 2006, 06:07:21 pm

Quote from: JM123 on November 28, 2006, 06:04:47 pm

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?

Title: Re: DI Calculations?
Post by: adixon on November 28, 2006, 06:45:27 pm

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

Title: Re: DI Calculations?
Post by: edd on November 28, 2006, 08:54:51 pm

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??

Title: Re: DI Calculations?
Post by: carlfoster on November 28, 2006, 09:31:03 pm

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.

Title: Re: DI Calculations?
Post by: freshwater on November 28, 2006, 10:40:34 pm

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 

Title: Re: DI Calculations?
Post by: Paul Coleman on November 28, 2006, 10:49:02 pm

Quote from: carlfoster on November 28, 2006, 09:31:03 pm

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.

Title: Re: DI Calculations?
Post by: JM123 on November 28, 2006, 10:53:02 pm

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)