OT: Calling chemists - water softening

I have a Karcher diesel steam cleaner, that can flash water to steam at any temperature up to 210 deg C. Simple coil with a diesel flame up the middle (actually down the middle!) with a single cylinder diesel engine squashing the water. It has provision for a 'water softening additive' to prevent build up in the coil but I cannot find what the additive should be. Karcher don't answer emails or messages. OK it was built for NATO for nuclear decontamination so it's not one of their highstreet models.

Any idea what the chemical additive might be?????

AWEM

Reply to
Andrew Mawson
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Big water softener plants use plain old salt.

Reply to
campingstoveman

was reading this

and advert came on the tv

Washing machines live longer with Calgon

wonder if you use that

all the best.markj

Reply to
mark

In article , Andrew Mawson writes

If you need the best purity, use de-ionised water - it has less dissolved solids than distilled water. Distilled water might be OK for this application though.

Domestic water softeners replace calcium (= probability of limescale deposits) with sodium, so you are likely to get salt deposited in the tubes. That will at least dissolve out easily, though it might cause some corrosion. I'm not sure, but I suspect Calgon does something similar, it does not really matter in a kettle where the boiled water is removed constantly, but it might where all the water is boiled to steam.

If you are able to wash out the coils regularly, something like Calgon might do the job.

David

Reply to
David Littlewood

. Andrew, Google 'Water softeners' and basically it is any traffic film remover.

And every firm and their aunty seems to have some.

I now know what should go into my pressure washer as well.

Thanks for the lead

Norman

Reply to
ravensworth2674

There is a chap over in uk-d-i-y who used to sell Karcher for many years, he might know.

Possibly

2-[2-(Bis(carboxymethyl)amino)ethyl-(carboxymethyl)amino]acetic acid (EDTA) or Sodium sesquicarbonate (trisodium hydrogendicarbonate) ?
Reply to
Peter Parry

message

steam

flame up

diesel

softening

their

That's to regenerate permutit type ion exchange softeners rather than actualy do the softening

AWEM

Reply to
Andrew Mawson

was reading this

and advert came on the tv

Washing machines live longer with Calgon

wonder if you use that

all the best.markj

...mm must be something similar. So what's in Calgon?

I seem to remember from my early schooling that there are type types of hardness - permanent and temporary - and boiling the water deposits the temporary type. But flashing off to steam I would have thought left any disolved chemicals behind nicely clogging up the coil in my steam cleaner - but I suppose an acid wash will get it off again.

AWEM

Reply to
Andrew Mawson

Depends on the country you buy it in. Either Sodium sesquicarbonate (Canada/Europe) or Sodium Carbonate/Sodium Citrate/Sodium Sulphate (Powder version - USA) or Sodium Hydroxide/Citric Acid (Liquid Version

- USA) and quite how they stop those last two simply neutralising each other I don't know.

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Reply to
Peter Parry

Would have thought a laundry magnate would have known the answer to this one.

Reply to
mark

Would have though some of the steam engine types would have known.

Something like

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combines a phosphate to minimise deposition, and polymers to prevent the deposits sticking.

You can add a bit more phosphate if the feed water is hard, as a field expedient, but it's cheaper to soften the water first. Not with a salt-revived water softener though, that just replaces the calcium and magnesium carbonates with salt.

Or use distilled water, or double reverse osmosis water if you can get a suitable grade, it'll be cheapest.

(btw deionised water does not necessarily have less dissolved solids than distilled water, though it may have if it's made from distilled water when it'll be much more expensive than distilled water - but distilled water has already been distilled, ie turned to steam and condensed, so it doesn't leave much residue when it's turned to steam again)

-- Peter Fairbrother

Reply to
Peter Fairbrother

Apparently not, hence his question.

He should have started a refrigeration business - then he'd have been a fridge magnate...

Regards, Tony

Reply to
Tony Jeffree

flame up

diesel

softening

their

Ah - but it's a different issue. We soften all our water (21 tons a day) using ion exchange permutit type softeners, but we don't aim to boil the water dry in the machines - only in extremis, then you're kippered

AWEM

Reply to
Andrew Mawson

Now even Mark with a dour Scotish form of humour must find that mildly amusing !

AWEM

Reply to
Andrew Mawson

In article , Peter Fairbrother writes

I'm sure there is a lot of variation, depending on what resin is used, and how the still is configured. However, I saw a film several decades ago which showed the remaining solids in tap water, distilled water and de-ionised water (using a proper industrial-type unit, not a domestic unit, which as both of us have said just replaces calcium with sodium).

The results, as far as I can recall, were that the distilled water had about 5% as much solids as the tap water, but still a surprising amount, presumably from carry-over in water droplets. The de-ionised water had less than 10% the amount in the distilled water. I can't be 100% certain, but I think the de-ioniser was fed with tap water.

David

Reply to
David Littlewood

If salt is for the regeneration cycle then why do I not have to put anything else in, "light on" its a bed of sand or something similar that catches the lumps.

Reply to
campingstoveman

In the washing machines I install, big enough to drive a small car into, if the customers softner fails we run an acid wash of 0.2 % concentration and a couple of goes with that clears the chalk.

Martin P

but I suppose an acid wash will get it off again.

Reply to
campingstoveman

catches the

The water passes over an activated resin bed that catches the calcium ions and replaces them with sodium ions. When it runs out of sodium ions then you regenerate by passing salt (sodium chloride) through to replace them and flush the calcium away.

AWEM

Reply to
Andrew Mawson

I don't quite understand the question, but here's how a salt-regenerating ion exchange water softener, eg those in a dishwasher, or most domestic ones, works.

The resin used is typically polystyrene with charged bits added. Being resin, it doesn't dissolve in water. The charged bits on the resin don't actually bind any ions, but they do get very upset [1] if there isn't an oppositely charged ion somewhere nearby. They don't mind much if the ions swap around though, any ion will do.

The supplied resin is loaded full of sodium cations and chlorine anions. The calcium, magnesium etc cations, and the sulphate and carbonate etc anions in the hard water replace these ions in the resin, and in turn the ions in the water are replaced by sodium and chlorine ions.

This replaces the calcium and magnesium salts with common salt, softening the water and making it slightly salty.

Some resins only replace the calcium and magnesium cations, and not the sulphate, carbonate etc anions.

Hard water is actually pretty dilute, and overall the ions are exchanged, not released, so there are still the same number of ions in the softened water. Because there are lots of sodium ions in the resin any ion leaving the resin is likely to be a sodium ion.

Similarly, because there are initially at least almost no sodium ions in the hard water, any ions going into the resin will be mostly calcium and magnesium ions. It is this imbalance in numbers which drives the flow.

After a while the calcium and magnesium ions in the resin build up, and the resin is refreshed by steeping it in concentrated salt solution. Because the solution is concentrated there are lots of sodium and chloride ions about, and these win the competition for most of the sites on the resin.

The used salt solution is discarded. However, you use a lot more salt than the amount of hardness you get rid of. [2]

Industrial ion exchange resins use acids and alkalis to flush out the unwanted ions. So-called "de-ionised" water is actually water where the impurity ions have been replaced by hydrogen and hydroxyl ions. which combine to form water.

[1] Think catastrophically upset, near-nuclear upset, certainly more energetically upset than mere chemistry - chemistry is what keeps something oppositely charged near, at least on the macro scale.. [2] The energy for the process comes from the energy released when salt is dissolved in water, or when salt solutions are diluted.

-- Peter Fairbrother

Reply to
Peter Fairbrother

Response from a fake chemist (biochemist) - If you want to descale the coil warm citric acid solution should work without causing too much harm to the innards - to prevent new scale build up Calgon is a proprietary (expensive) solution but good old fashioned washing soda (sodium carbonate) is a cheaper alternative.

Reply to
skiprat

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