Feed Water

[Richard SimpsonParticipant @richardsimpson88330]

I’d appreciate the thoughts of the collective experience here.

Being from a marine engineering background I am well aware of the importance of using the best quality feed water for our boilers.  Also being a Yorkshireman I am conscious of the cost implications of buying bottled distilled water so I have in the past used either water collected from a tumble drier, after suitably filtering it of course, or water collected by a dehumidifier, again after filtering it.

Recently however I have stripped a boiler down after only a few short runs and found evidence of limescale deposits in fittings.  I have consequently decided that a better quality of water would be beneficial for this model at least.  The trouble is my local suppliers only sell de-ionised water for £3.99 for a 5 litre bottle whereas I can get distilled water on line for £10.99 for 5 litres.  I have always believed that de-ionised water is not good for boilers as it is such a good electrolyte that it can lead to leeching certain metals out of the silver solder and eventually compromise the strength of joints.

My question is therefore does anyone have experience of using de-ionised water in their boiler and have they seen any detrimental effects or is it all a bit of an old wives’ tale and, for the amount of use we give our boilers, we are never going to see any challenges?

 

[renardiere7Participant @renardiere7]

Surely de-ionised water is the complete opposite of an electrolyte?

[noel shelleyParticipant @noelshelley55608]

I and my local club use rain water, I believe this is a common practice. There may be some small contamination as it falls and I always filter to remove debris. Noel.

[JasonBModerator @jasonb]

Water treatment added to the water will prevent scale buildup and allow tap water to be used.

[Robert Atkinson 2Participant @robertatkinson2]

Buy DI water and put a sample of the metal(s) of concern (a cleaned up bit of silver soldered copper and a bit of brass for example) in the bulk container. This will will scarifice enough ions in a week or two to protect your boiler.
ou could also use an ion exchange resin water filter jug e.g. Brita to make your own DI.
Personally I think the issue is over inflated. The problem is possibly over inflated from issues in high cleanliness processes like semiconductor manufacture.

An example of my direct experience relates to aircraft gas turbine engines. It is standard practice to wash the compressor and tubines of engines with water (and other materials including detergent or ground walnut shells) to remove dirt and corrosive deposits. We operateed to and from islands at low levels so salt was an issue both for buildup causing loss of compressor efficency and chlorine causing corrosion of the turbines. So we reguarly washed the engines with distilled water that was locally sourced in 25l containers from an industrial supply company. Despite this a “hot section” inspection revealed corrosion on a turbine. one blade had a “blister” about 2mm across. This was analysed and found to be a sulphur compound. This was unexpected. Investigation revealed that the distilled water was contaminated with sulphuric acid. The suppliers main customer was a battery company who also bought H2SO4. This came in identical returnable containers. The supplier didn’t bother seperating the water and acid  containers and their other customer didn’t acre mecause the mixed them anyway.
So we switched to a different water suplier. I found out who when I was going into town and was asked if I could pick up some water from Boots. There were too many 5l containers of BP grae distilled water to fit in my car. It was expensive too. I suggested we bot an Elgastat DI water “filter” and made our own DI. The leaching issue was brought up as the engine manual only said distilled. The manufacturer confirmed that DI was OK to use. We never had a corrsion issue after switching to self-droduced DI. Note that Nickel is a metal that is used in turbine blades and is leached by DI.

Robert.

[renardiere7]

On renardiere7 Said:

Surely de-ionised water is the complete opposite of an electrolyte?

So where does the advice not to use it come from?  And why?  Or have we simply fallen into a trap of believing old stories based on myth?  I really don’t know.

[JasonB]

On JasonB Said:

Water treatment added to the water will prevent scale buildup and allow tap water to be used.

Now that is interesting Jason, very many thanks for that.  I have only recently started to use their Universal Steam Oil, after a very enlightening and interesting conversation with one of their team, as well as a technician from Morris Lubricants.  I should have thought about their water treatment as a possibility.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

Buy DI water and put a sample of the metal(s) of concern (a cleaned up bit of silver soldered copper and a bit of brass for example) in the bulk container. This will will scarifice enough ions in a week or two to protect your boiler.
ou could also use an ion exchange resin water filter jug e.g. Brita to make your own DI.
Personally I think the issue is over inflated. The problem is possibly over inflated from issues in high cleanliness processes like semiconductor manufacture.

An example of my direct experience relates to aircraft gas turbine engines. It is standard practice to wash the compressor and tubines of engines with water (and other materials including detergent or ground walnut shells) to remove dirt and corrosive deposits. We operateed to and from islands at low levels so salt was an issue both for buildup causing loss of compressor efficency and chlorine causing corrosion of the turbines. So we reguarly washed the engines with distilled water that was locally sourced in 25l containers from an industrial supply company. Despite this a “hot section” inspection revealed corrosion on a turbine. one blade had a “blister” about 2mm across. This was analysed and found to be a sulphur compound. This was unexpected. Investigation revealed that the distilled water was contaminated with sulphuric acid. The suppliers main customer was a battery company who also bought H2SO4. This came in identical returnable containers. The supplier didn’t bother seperating the water and acid  containers and their other customer didn’t acre mecause the mixed them anyway.
So we switched to a different water suplier. I found out who when I was going into town and was asked if I could pick up some water from Boots. There were too many 5l containers of BP grae distilled water to fit in my car. It was expensive too. I suggested we bot an Elgastat DI water “filter” and made our own DI. The leaching issue was brought up as the engine manual only said distilled. The manufacturer confirmed that DI was OK to use. We never had a corrsion issue after switching to self-droduced DI. Note that Nickel is a metal that is used in turbine blades and is leached by DI.

Robert.

Thanks Robert, very interesting.  You might be interested to know that marine diesel engines also benefit from regular cleaning of the gas side of the turbo-chargers.  I once joined a ship to discover they were having horrendous problems with their generators, which would not share load effectively and every standby was a bit of a nightmare as we were continuously rebalancing load manually as we ran winches and thrusters.  A bit of digging uncovered the fact that the turbocharger water washing drains were blocked so water washing had obviously not been done for some time.  We made our own nut washing systems, fitted them and tried them out.  The first time we used it we covered half the ship with soot.  Instigating a strict regimen of water washing and nut washing returned the engines to stable and reliable operation.  The fight I had to persuade the long standing engineers that shooting a cup of walnut shells into the turbochargers was the right thing to do was lengthy!

[Richard Simpson]

On Richard Simpson Said:

On renardiere7 Said:

Surely de-ionised water is the complete opposite of an electrolyte?

So where does the advice not to use it come from?  And why?  Or have we simply fallen into a trap of believing old stories based on myth?  I really don’t know.

An electrolyte by definition contains ions. It is a material that conducts electricity by movment of ions rather than by movement of electrons. So renardiere is correct DI  is most cetrtainly not an electrolyte. In practice the purity of DI is tested by measuring it’s electrical conductivity. The lower the conductivity the purer the water.
Putting DI in contact with a source of ions turns it into an electrolyte to some degree.

Robert.

[SillyOldDufferModerator @sillyoldduffer]

Another difference between Railway and Marine practice!

As opportunities to clean boilers at sea are limited and the consequences of breakdowns are severe, it pays to take extreme care with boiler water.   Steam loco boilers are less demanding.  They were maintained daily and regularly washed out, plus locos can easily be towed back to the depot if they break down.   So railways tended to fill their boilers with ordinary water, only treating if it was exceptionally bad.    Agricultural traction engines filled up from any handy ditch.

Model boilers are different again.

There isn’t a black and white answer because it depends on the Requirement.   What does the owner want and how much is he prepared to spend?    We want the best for our models but dislike spending money!   It’s about compromise.

Choices:

• Tap water is mostly ‘good enough’ for those living in a soft-water area, otherwise water-softened hard tap-water is similarly ‘good enough’. Safe to drink.   But water-softening chemicals only remove the Calcium and Magnesium salts responsible for scale.  There will be some Chlorine, Oxygen and Carbon Dioxide in it, plus small quantities of Iron, Copper and Lead from the pipework.
• Rain-water is generally pure and cheap.   Purity is affected by how it’s collected: running over dirty roofs, pollution, and maybe dirt rendered airborne by wild-fires and storms.   Should be filtered and I wouldn’t risk drinking it!  Contains dissolved gases, Oxygen, Carbon Dioxide, and Nitrous Oxides, maybe Sulphuric Acid from coal burning.
• De-ionising removes metal salts and some gases. Unsafe to drink because it doesn’t remove bacteria or viruses, otherwise very clean.  Unlikely to damage a model boiler.  Perfumed deionised water for steam irons is probably harmless, but no-one has tested it.   Main disadvantage is cost.
• Distilling removes almost all contamination, but is very pricey.

Cheap sources like freezer frost, dehumidifier and tumble drier water are pretty filthy in my experience.  Whilst the salts that cause scale are removed, the water contains bits of fish-finger, dust, and lint.  I wouldn’t drink any of them and no one knows if they will damage a model boiler or not.

The chemistry inside a boiler is on the extreme side.  High-pressure, high-temperature water, steam, plus whatever gases were in the water and air when the boiler was filled.  Certainly capable of breaking down anything organic, dislodging old flux, corroding metal, and dezincifying any handy Brass.  Conditions vary wildly between hot and cold cycles.

I suspect most damage is done when boilers are out of service.  Damp Oxygenated air left for weeks on end inside is slow-but-sure corrosive.    My book on full-size recommends either drying out the boiler thoroughly and sealing after filling with dry Nitrogen, or, filling completely with thoroughly boiled pure water to remove dissolved gases, and then sealing.   In both cases the boiler is stored full of cold inert material, air kept out!

In practice, Richard can safely use de-ionised water if he wishes, and definitely need not waste precious spondulicks on Distilled Water.  In a hard-water area rain-water is best value for money – provided there’s a space for a water-butt, and a filter.

Dave

[cogdobblerParticipant @cogdobbler]

Whole world of difference between  21st century marine practice on 1,000 psi superheated boilers supplying turbines and 19th century steam locos chuffing along.

But in the 1920s, according to my grandfather who sailed on them,  Grimsby trawlers ran seawater in their boilers. They just shovelled the salt out at the end of every 3-week sojourn at sea. More primitive even than the railways!

 

[Richard SimpsonParticipant @richardsimpson88330]

Lots of interesting food for thought there gents.  Many thanks for taking the time to share.  I think my challenge here is that the tap water is very hard.  Consequently we have had a softener fitted.  Having said that I have only used this boiler a couple of times, then it has sat on the shelf for a couple of years and fittings were noted as having limescale in them, so obviously I need to do better.

If I can strain the brain to remember something about the deionised water issue, I think it was something along the lines of, when the water is deionised it tries to restore the removed ions, which it does by leeching them from some surrounding metals that it is in contact with.  This is not then a normal electrolytic process as we associate with a cell but more of a chemical reaction.  If that sounds confusing I apologise.  As Robert first mentioned, putting a chunk of silver soldered copper into the container should help to stop it happening in the boiler.

Today the test is with neat deionised water, let’s live on the edge!

Dave, an interesting aspect of very early steam engines in coastal ships was the fact that they used raw sea water as feed.  Consequently the engineers spent a large proportion of their time in port, inside a hot boiler, cleaning soot out of the fireboxes and scraping salt out of the water spaces.  When I first read that a few years ago I was simply amazed.  Nowadays if your boiler water chloride levels go above around 50 ppm people start to get very excited.  And that is only in low pressure auxiliary boilers.  High pressure main propulsion boilers are a lot lower.

[duncan webster 1Participant @duncanwebster1]

If you read Wardales book about the Red Devil he waxes lyrical about keeping total dissolved solids (TDS) high. I think this is to control priming, but clearly keep it below the level at which scale develops

[duncan webster 1Participant @duncanwebster1]

By the way the book is a good cure for insomnia.

[BazyleParticipant @bazyle]

Some of the de-ionising methods are aimed at domestic steam irons, kettles etc so primarily interested in removing the calcium to avoid it furring things up. They do this not by removing the salts but swapping them for something that doesn’t settle out when heated. So not actually de-ionising nor distilling equivalent. These types can then swap back with the copper in your boiler, especially the zinc when we still used brass fittings.

We used to have a rainwater collection and settling tank in our old site and the leaves that came off the roof were left in because nobody could be bothered to clean it and as tannin is used for boiler treatment it was considered beneficial.

Since everyone with a workshop ought to be running a dehumidifier if not living in the Sahara it makes sense to use the output. Just note they catch a little oil vapour, dust, and the condenser gradually corrodes releasing a very small amount of contamination. Use a coffee filter if unable to use a settling tank.

[noel shelleyParticipant @noelshelley55608]

Bazyle s mention of a coffee filter is what I use but it is the nylon type and works like a charm. Mine have also filtered 1000s of gallons of used cooking oil for bio diesel. Noel.

[SillyOldDuffer]

On SillyOldDuffer Said:

Another difference between Railway and Marine practice!

As opportunities to clean boilers at sea are limited and the consequences of breakdowns are severe, it pays to take extreme care with boiler water.   Steam loco boilers are less demanding.  They were maintained daily and regularly washed out, plus locos can easily be towed back to the depot if they break down.   So railways tended to fill their boilers with ordinary water, only treating if it was exceptionally bad.    Agricultural traction engines filled up from any handy ditch.

Model boilers are different again.

There isn’t a black and white answer because it depends on the Requirement.   What does the owner want and how much is he prepared to spend?    We want the best for our models but dislike spending money!   It’s about compromise.

Choices:

• Tap water is mostly ‘good enough’ for those living in a soft-water area, otherwise water-softened hard tap-water is similarly ‘good enough’. Safe to drink.   But water-softening chemicals only remove the Calcium and Magnesium salts responsible for scale.  There will be some Chlorine, Oxygen and Carbon Dioxide in it, plus small quantities of Iron, Copper and Lead from the pipework.
• Rain-water is generally pure and cheap.   Purity is affected by how it’s collected: running over dirty roofs, pollution, and maybe dirt rendered airborne by wild-fires and storms.   Should be filtered and I wouldn’t risk drinking it!  Contains dissolved gases, Oxygen, Carbon Dioxide, and Nitrous Oxides, maybe Sulphuric Acid from coal burning.
• De-ionising removes metal salts and some gases. Unsafe to drink because it doesn’t remove bacteria or viruses, otherwise very clean.  Unlikely to damage a model boiler.  Perfumed deionised water for steam irons is probably harmless, but no-one has tested it.   Main disadvantage is cost.
• Distilling removes almost all contamination, but is very pricey.

Cheap sources like freezer frost, dehumidifier and tumble drier water are pretty filthy in my experience.  Whilst the salts that cause scale are removed, the water contains bits of fish-finger, dust, and lint.  I wouldn’t drink any of them and no one knows if they will damage a model boiler or not.

The chemistry inside a boiler is on the extreme side.  High-pressure, high-temperature water, steam, plus whatever gases were in the water and air when the boiler was filled.  Certainly capable of breaking down anything organic, dislodging old flux, corroding metal, and dezincifying any handy Brass.  Conditions vary wildly between hot and cold cycles.

I suspect most damage is done when boilers are out of service.  Damp Oxygenated air left for weeks on end inside is slow-but-sure corrosive.    My book on full-size recommends either drying out the boiler thoroughly and sealing after filling with dry Nitrogen, or, filling completely with thoroughly boiled pure water to remove dissolved gases, and then sealing.   In both cases the boiler is stored full of cold inert material, air kept out!

In practice, Richard can safely use de-ionised water if he wishes, and definitely need not waste precious spondulicks on Distilled Water.  In a hard-water area rain-water is best value for money – provided there’s a space for a water-butt, and a filter.

Dave

On SillyOldDuffer Said:

Another difference between Railway and Marine practice!

As opportunities to clean boilers at sea are limited and the consequences of breakdowns are severe, it pays to take extreme care with boiler water.   Steam loco boilers are less demanding.  They were maintained daily and regularly washed out, plus locos can easily be towed back to the depot if they break down.   So railways tended to fill their boilers with ordinary water, only treating if it was exceptionally bad.    Agricultural traction engines filled up from any handy ditch.

Model boilers are different again.

There isn’t a black and white answer because it depends on the Requirement.   What does the owner want and how much is he prepared to spend?    We want the best for our models but dislike spending money!   It’s about compromise.

Choices:

• Tap water is mostly ‘good enough’ for those living in a soft-water area, otherwise water-softened hard tap-water is similarly ‘good enough’. Safe to drink.   But water-softening chemicals only remove the Calcium and Magnesium salts responsible for scale.  There will be some Chlorine, Oxygen and Carbon Dioxide in it, plus small quantities of Iron, Copper and Lead from the pipework.
• Rain-water is generally pure and cheap.   Purity is affected by how it’s collected: running over dirty roofs, pollution, and maybe dirt rendered airborne by wild-fires and storms.   Should be filtered and I wouldn’t risk drinking it!  Contains dissolved gases, Oxygen, Carbon Dioxide, and Nitrous Oxides, maybe Sulphuric Acid from coal burning.
• De-ionising removes metal salts and some gases. Unsafe to drink because it doesn’t remove bacteria or viruses, otherwise very clean.  Unlikely to damage a model boiler.  Perfumed deionised water for steam irons is probably harmless, but no-one has tested it.   Main disadvantage is cost.
• Distilling removes almost all contamination, but is very pricey.

Cheap sources like freezer frost, dehumidifier and tumble drier water are pretty filthy in my experience.  Whilst the salts that cause scale are removed, the water contains bits of fish-finger, dust, and lint.  I wouldn’t drink any of them and no one knows if they will damage a model boiler or not.

The chemistry inside a boiler is on the extreme side.  High-pressure, high-temperature water, steam, plus whatever gases were in the water and air when the boiler was filled.  Certainly capable of breaking down anything organic, dislodging old flux, corroding metal, and dezincifying any handy Brass.  Conditions vary wildly between hot and cold cycles.

I suspect most damage is done when boilers are out of service.  Damp Oxygenated air left for weeks on end inside is slow-but-sure corrosive.    My book on full-size recommends either drying out the boiler thoroughly and sealing after filling with dry Nitrogen, or, filling completely with thoroughly boiled pure water to remove dissolved gases, and then sealing.   In both cases the boiler is stored full of cold inert material, air kept out!

In practice, Richard can safely use de-ionised water if he wishes, and definitely need not waste precious spondulicks on Distilled Water.  In a hard-water area rain-water is best value for money – provided there’s a space for a water-butt, and a filter.

Dave

 

[Charles LamontParticipant @charleslamont71117]

After a change in the water source for the mains supply in Bridgnorth, the Severn Valley Railway had a huge problem with priming. The water is now pretty hard, and the SVR now uses a reverse osmosis plant for boiler water. Boilers are also dosed with tannin (I think when filled from empty).

[Paul LousickParticipant @paullousick59116]

I can’t comment on de-ionised water as I have a bigger engine that consumes 50+ litres per day and would be too expensive and you have already mentioned that you have fitted water filters.

You also noted that you only used the boiler a couple of times, so if it is only going to be use occasionally, flush the boiler out after use with scale remover that is used to clean coffee machines and irons after use before storing.

[Paul KempParticipant @paulkemp46892]

Considering the original question I have no experience of using either distilled or de ionised water in minuscule boilers.  I have seen filtered rainwater used in3 1/2” / 5” gauge loco’s and seen the internals of those boilers which have been scale free but seem to have a dark powdery residue – I assume due to rainwater being generally mildly acidic.

Turning attention to water quality for industrial / commercial boilers the Spirax Sarco web site provides some good common sense information.  They recommend for small boilers which in their view are still a lot lot larger than those being discussed here and operating at higher pressure’s and temperatures maintaining a ph of around 11 and a maximum TDS of 2000.

Any boiler monitoring / water treatment program needs to achieve 2 things, firstly prevention of scale build up on internal surfaces which will act as an insulator detracting from performance and also potentially damaging to the boiler structure by plates or tubes overheating.  Secondly to protect the boiler internal surfaces exposed to the water (and steam) from corrosion.

Prevention of scale which is a product of dissolved minerals and salts in the raw feed water can be achieved either by putting the raw water through processes like resin beds to remove the bad stuff or by just adding chemicals to modify the behaviour of the bad stuff as it comes out of solution in the boiler to prevent it adhering to the internals (allowing it to be blown out).

Treatment chemicals of the latter type generally include a ph modifier and substances to react with the precipitated solids that form ‘scale’ to prevent them adhering to the boiler internals and allow them to be removed by blowing down and a corrosion inhibitor which is usually a tannin base.  To use these chemicals to best effect at least three parameters of the boiler water should be monitored, tannin index (the amount of tannin present), ph and TDS.  High ph in steel boilers is to be avoided as above 12 at high temperatures (pressure) it can lead to cracking, high TDS will cause priming and an excessive tannin index will result in a tannin build up which is just as detrimental as scale in terms of insulating surfaces detracting from performance and potentially overheating plates.

It is worth understanding that with our type boilers which are generally total loss that the steam evaporates and is consumed leaving the impurities (and treatment) in the boiler.  Thus the concentration of scale forming elements in the boiler water increases proportionally to the make up water added.  So the longer and harder you run the boiler the worse the situation becomes.  It is also worth understanding that when you do a (proper) blow down the concentration of treatment drops.  So boiler water quality management and control is a moving target, is a science in itself or even a black art and is highly dependent on the quality of water put in.

None of this will be news to the OP as a marine engineer either on steam or diesel (we used to check the jacket water treatment weekly as corrosion in an engine water circuit prevents proper heat transfer just the same as a boiler) So to the original question the gold objective with very small boilers must be to use water with no scale forming impurities.  Corrosion in my opinion given the very low hours in steam and the non ferrous materials used (excluding brass for obvious reasons) is likely to be minimal with all the options mentioned.  The second option is to use a boiler water treatment but this will require a carefully implemented regime including blow down and wash out to remove the scale held in suspension (sludge).  From my experience so far implementing a treatment regime on a small (40 litres at running level) steel boiler in various geographical locations with differing water hardness this is not as easy as it sounds!  Last and possibly the best or cheapest option as mentioned by others is to use what comes out of the tap and carry out a regular descale, after all that is what you do with your kettle and that boils far more water in a year than a tiny boiler (or it does in my house!)

Paul.

[Richard SimpsonParticipant @richardsimpson88330]

Again many thanks gents for sharing such a mine of information.  As Paul has correctly suggested I am quite familiar with the ins and outs of full sized marine practise and a significant part of my early days in the industry was spent testing and maintaining various levels in boiler water, main engine jacket cooling water, main engine piston cooling water, main engine injector cooling water, compressor cooling water, auxiliary engine cooling water, etc..  Consequently I am aware of the concerns with treatment and all its potential consequences.

I think, from all I have read here, much as I think Jason’s suggestion of water treatment has merit, for a small, low pressure model boiler with a total loss feed system, the best possible solution is to simply minimise the impurities going in rather than try to deal with them once they are in.  In my case blowing down is possible but descaling is a pain as the whole model has to come apart.  Using tap water, even with a water softener in use, still produces a lot of scale in the kettle so I’m sure there remains enough impurities to be of concern.  To this end I am probably more convinced than ever that buying either distilled or de-ionised water is worth it in the long run.

I’m still left with the question though as regards whether de-ionised water is actually bad for a model boiler.  As per Dave’s comment and bearing in mind the amount of running time the model is likely to see, I suspect that using de-ionised water isn’t going to be much of a problem.

[Richard Simpson]

On Richard Simpson Said:

…Dave, an interesting aspect of very early steam engines in coastal ships was the fact that they used raw sea water as feed.  Consequently the engineers spent a large proportion of their time in port, inside a hot boiler, cleaning soot out of the fireboxes and scraping salt out of the water spaces.  When I first read that a few years ago I was simply amazed.  Nowadays if your boiler water chloride levels go above around 50 ppm people start to get very excited.  And that is only in low pressure auxiliary boilers.  High pressure main propulsion boilers are a lot lower.

I’ve long been interested in Marine Steam, which is more demanding in many ways than locomotives.  Though ships also have more capacity for adventurous engines, the engineer isn’t free to do as he likes – get the centre of buoyancy wrong and the ship becomes unstable.

The development of marine steam is fascinating, starting with Brine filled pot boilers providing low-pressure steam to grossly inefficient large cylinder engines, and ending up with high-pressure super-heated steam from sophisticated fire-tube boilers feeding quadruple expansion engines with a low-pressure turbine on the exhaust.

Warships are interesting because they had to do high-speed, and there are some hairy descriptions of the pre-turbine Navy trialling reciprocating steam engines well beyond their sensible limits.   Bearings cooled by fire-hoses, fountains of oil, steam leaks galore, and parts breaking right left and centre. One test wore the engines out completely in two days and the vibration damaged the hull and fittings. (No one seems to have worried about the crew!)

Switching to turbines solved many problems, but then Navies were bedevilled by “condenseritus”.   Condensors extracted maximum power and efficiency from steam, and then recycled water back to the boiler.  A box of many jointed pipes was cooled by sea-water, and a tiny leak would contaminate badly enough to quickly damage the boiler and engine.  Pure water was vital.

Whilst fighting navies encountered problems due to their need for speed, merchant navies hit different issues due to their need for reliable efficiency.   Today, fast warships tend to go for gas turbines whilst merchant ships prefer diesel, at least for propulsion.   But there are many mixed examples, some warships require long range, and some merchantmen need speed.

Lots of interesting nautical modelling opportunities, both main and auxiliary steam.  A steam winch would make a good model, as would a steering-engine.   For some reason marine subjects have become unpopular, along with many other worthy industrial objects like textile machinery, mining equipment, steam hammers, excavators, cranes, pumps, full-size Stirlings, and mid-Victorian railway engines.    Napoleonic era ship’s cannon are fairly popular, but not the Moncrieff disappearing guns used to defend harbours, let alone an octuple Bofors!   Even simple things like Davy lamps and sextants are rarely done, despite being attractive objects.

More boats please, I love ’em!

Dave

 

[duncan webster 1Participant @duncanwebster1]

The advice from industry sources is aimed at steel boilers. Not saying it wrong, but our boilers tend to be copper. Is tannin relevant? Unless something has gone awry at the treatment works, tap water is never acidic. Rain water is, that’s why it dissolved limestone to form caves. I seem to remember tri sodium phosphate being added to the water on NG locos to prevent scale deposition. Had to be monitored weekly.

[noel shelleyParticipant @noelshelley55608]

Whilst the marine world is fascinating for the machinery it used and a real steam anchor windlass can be had for the sake of recovering it from the semi submerged wreck of the Vina in the entrance to Brancaster Harbour, the issue of feed water interests me !

Having read the advice/sales info on water treatment and the mix being 0.3% I wonder how well one could maintain this except by having a storage tank of say 25L/5gals and adding 80ml and then taking said mix with one to the track or place of operation. It could get very tiresome ?

With my loco being at least 45 years old and not knowing it’s history, the slight acidic nature of the rain water I would think will be taken care of by any the deposits that are probably already there. A bore scope through the safety valve bush will reveal the true state of play. An old stainless sink sat on top of a 25L drum makes a simple rain water catcher, with a plastic tea strainer over the waste outlet. The winter and a few 25L drums will keep one supplied.

PS Dave, the Vina still has her triple expansion engine and most of her boiler in, she’s dry at low water !   Noel.

[cogdobblerParticipant @cogdobbler]

If  you Google “copper in deionised water” you will find some interesting reading. The gist seems to be the de-ion water is “hungry” to rob ions from the metal.

[Author]

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