Flow rate for DI unit.

What is the maximum flow rate through a small (say 11 litre) DI bottle for purifying small quantities of 250 ppm tap water?

My reason for asking is because I have a small number of customers who have really difficult windows to reach trad even with a pole and (as I already have wfp kit) I was wondering if I could get away with purifying tap water directly from the tap to use on these few windows. It may be only 5 or 10 per week, so I don't want to be investing in RO for such a small amount of water use and I don't want to be carrying cans of pure water around with me.

The flow rate I'd need would only be about 5 lpm at the very maximum.

So my question boils down to "Can you use DI to purify tap water directly from a tap for use with a wfp?"

Yes, sure you can. But if the local tds readings are high, you will eat through the granulate incredibly fast.

No problems, I would run it through at half on tap and that will see you ok. I don't know what your tap pressure/lpm is where you are but where I'm at it's approx 12lpm at 45psi. At the usage your needing pure for I would say it would be OK 

I can always turn the tap down to reduce the flow rate. It needs to be just fast enough to actually clean a window. I've just measured my flow rate for the first time ever! At normal working it's about 1.5 lpm and frighteningly fast it's 2.5 lpm. That's direct from the tap.I use a single over the top wide fan jet recycled from a carpet cleaning machine.

Nudel said:

Yes, sure you can. But if the local tds readings are high, you will eat through the granulate incredibly fast.

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According to Gardiner's resin calculator the cost per litre is about 4p. Yes, that would be too much if I was using wfp all the time, but it's only going to be for a very few occasional windows. Each one uses about 2 or 3 litres and I price them at double as they're difficult to do, so it should be OK.

Yes you can this is what I do with our windows. Live in a rural area and water is medium hard and is rung through a 11 litre DI Vessel. Anything over 200 pm I would advise using a 15 litre vessel and that will be suitable.

If you have high ppm and use a small vessel it will not work as there is not enough resin in the vessel to cope with the load,

As much as 4p a litre ? That seems high

Here's a link to the calculator: http://www.gardinerpolesystems.co.uk/Resin_Calculator.htm

Just bought this.

http://www.cleaningspot.co.uk/acatalog/7L-Vessel-complete-full-of-DI-resin-PV7F.html

It should be big enough for the job at a 2 or 3 lpm flow rate.