# Fresh water making - outside a 20 mile limit?



## Blackstone

On every FW evaporator/ generator is the sign "This plant should not be used for the production of water within 20 miles of any coastline". 

Does anyone know where this rule came from, and how it is enforced?


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## James_C

Never heard of that one before. We certainly make FW when within 20 miles of the coast.


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## chadburn

Advisory rather than mandatory, to do with sewage out falls and sludge dumping from Dredging.


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## A.D.FROST

Because you are boiling water(vac.) at less than 100 C which does not kill off all the germs etc.Its not a law but commonsense not to flash it up close to shore and is manufactures instructions for those who need to ask.


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## stevekelly10

You can make water within the 20 mile for use in boiler water, but not for potable drinking water.


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## makko

There are two basic reasons:

1. As previously mentioned, due to sewage discharges, dumps, dredging residue, etc., up to 20 miles out from shore there may be bacteria may not be killed/eliminated meaning that the water is not potable.

2. In very large deltas, there may be considerable silt and fines entrained in the seawater. Potable water should contain less than 500 mg/litre of suspended solids while good quality boiler feed will contain less than 2.5 mg/litre!

Another consideration is that the vessel will be going onto standby and due to the fluctuations in engine revs, there may be an upset in the heat balance causing the engine to shut down.

It is always prudent when starting up to dump the first few tons into the boiler feed water tank to ensure that the system is thoroughly flushed through.

Rgds.
Dave


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## OliverD

*Distilling plant priorities*

Makko said:
"It is always prudent when starting up to dump the first few tons into the boiler feed water tank to ensure that the system is thoroughly flushed through."

In my U S Navy time, when first starting the still, I remember dumping the first run over the side (or dump in the bilges on many surface ships). I don't remember the ppm limits, but I do recall the best water went for battery top-off on the subs. The next best water was used for boiler feed, and the crew's potable water was third priority, although kept within strict limits. 
I know the BT's took great care in maintaining the purity of their boiler systems.
The auxiliary gang included some of us Enginemen.


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## waldziu

In the RN we would not put the evaps to Ships tanks until approx three miles out. If we had to limit to 20 miles we would be up a gum tree when exercising in the Channel. I may be wrong but I'm told that one cannot taste salt in water at less than 500 ppm. Our boilers got sick at anything over 20 ppm.


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## chadburn

On the subject of the Channel and it's approaches re contamination I read that Maersk have been Fined for the unlawful discharging (who can forget the story of the secret pipes) of Palm Oil whilst tank washing off the South Coast. Her Master maintained that he was doing nothing illegal as he was outside the 12 Mile limit. Unfortunately up pops a Satellite over the horizon and photographs his vessel inside the 12 mile limit with a distinctive discharge trail. There were areas in the Middle Sea where I would have to be desperate to lift sea water from due to the contamination.


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## twogrumpy

There was a programme on TV with an RN ship up Chittagong way, and what I took to be the engineering officer complaining about problems making water.
He had this inlet filter which was so choked and fithy that I would not have wanted to handle it with elbow length gloves, godness knows where he was attempting to making water to.
Knowing nothing about reverse osmosis plants could this have been what he was running, and can they make potable water from such filth.


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## Klaatu83

In my 30 years at sea I never heard of anyone on a ship making drinking water while the ship was in any harbor or river. Of course, that doesn't apply among landsmen. Where I live there is currently a proposal to construct a water purification plant to convert the water of the Hudson River into drinking water. Practically everybody in the region thinks it's a bad idea, apart from the water company and the politicians that they have bought. Incidentally, apart from being brackish, and the presence of sewage, there is a nuclear power plant almost directly across the river from the location where they intend to build the water purification plant. In addition PCBs are known to be in the river water, originating from the silt at the bottom of the river beside the old General Electric plant, a hundred miles upstream.


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## Chris Isaac

Klaatu83 said:


> In my 30 years at sea I never heard of anyone on a ship making drinking water while the ship was in any harbor or river. Of course, that doesn't apply among landsmen. Where I live there is currently a proposal to construct a water purification plant to convert the water of the Hudson River into drinking water. Practically everybody in the region thinks it's a bad idea, apart from the water company and the politicians that they have bought. Incidentally, apart from being brackish, and the presence of sewage, there is a nuclear power plant almost directly across the river from the location where they intend to build the water purification plant. In addition PCBs are known to be in the river water, originating from the silt at the bottom of the river beside the old General Electric plant, a hundred miles upstream.


Yes but apart from the salt, sewage, PSBs and radio activity it's probably perfectly safe to drink...... cheers!


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## chadburn

The first thing in my Grip these days is my Brita Filter jug and filter pack!!!(Thumb)


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## Mike S

Ye Gods.......what were we drinking in the "good old days"? Potable water out if Aden tasted like castor oil, water taken on board in Rotterdam tasted like some thing out of a swimming pool and was reputed to have been used four times before we got it. Just to name a couple of places. Galveston water took a little getting used to however after 6 months stuck there we got used to it. 
All this from FW tanks that were cement washed just to boost the flavour a little.
No wonder I got kidney stones later in life! 
.......as for evaps, On Durham built in 1934! Yeah right!
Tell it to the kids today;eeh aye etc.......! (Smoke)


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## Derek Roger

I had an occasion when in Madras on the Brocklebanks Markhor  and strike bound for a while and we were almost out of water and due to a drought there was none available at any cost from shoreside that we had to make water in port .
We had sufficient potable water in the aft peak to last for drinking and cooking for some time .
The aft peak was isolated and our crew drew of water for the galley by means of a hand pump into containers which were carried up to the galleys as needed .

The low pressure Evap which operated at about 22 inches vacuum ( Atlas as I recollect ) was normally heated by the main engine jacket water but also had a steam coil. We changed over to the steam coil which was supplied by the donkey boiler .
We were able with some difficulty to make about 5 tons per day which we heavily chlorinated and stored in the other FW tanks which was fine for showers / laundry etc. When we eventually left port we were able to dunp the :in port : water and chlorinate and flush the tanks before refilling with good potable water .
Not a recommended process but to be without water for washing and laundry for days on end we had no option .
No ill effects .
As an aside we had a very efficient water hardening unit and the water we made at sea was quite palatable ( good enough to mix with ones Scotch or drink by itself ) Later vessels were also provide with an ultra violet system which ensured no bacteria .

Regards Derek


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## Coastie

Klaatu83 said:


> In my 30 years at sea I never heard of anyone on a ship making drinking water while the ship was in any harbor or river. Of course, that doesn't apply among landsmen. Where I live there is currently a proposal to construct a water purification plant to convert the water of the Hudson River into drinking water. Practically everybody in the region thinks it's a bad idea, apart from the water company and the politicians that they have bought. Incidentally, apart from being brackish, and the presence of sewage, there is a nuclear power plant almost directly across the river from the location where they intend to build the water purification plant. In addition PCBs are known to be in the river water, originating from the silt at the bottom of the river beside the old General Electric plant, a hundred miles upstream.


Not to mention the odd aeroplane or two!!


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## waldziu

Whilst off Karachi we took on water from shore and chlorinate it and left for 24 hours. The whole crew came down with amebic dysentery. The Shipwright had to be hospitalised in the Seychelles our next port of call.


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## BOB.WHITTAKER

Whilst on a Jack Up rig in Morecambe Bay circa 1983 we were using a reverse osmosis unit to produce water until Sellafield "did a dump" . That put a stop to it , much to the delight of the duty mechanic / motorman who could spend 80 % of a shift " nursing " the plant . They were extremely fragile and tempremental and the amount of consumables they required was totally unacceptable .


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## BOB.WHITTAKER

Further comment on Morecambe bay and Sellafield , the Mussels on the rig legs when we brought them up to do a rig move were enormous , but again Sellafield put a stop to the harvest .


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## funnelstays

I was an on chemical tanker carrying inhibited styrene monomer.The main sea water overboard from the dump steam condenser sprung a substantial seawater leak which meant a steam shut down,as we could not use the cargo heating coils as they had to be blanked off for the carriage of the styrene.It was decided to use the steam side of the vap which had never been tried to substitute as the dump condenser.After a few hours of checking adjusting and fiddling it magically started producing fresh water at a greater rate and a lower ppm than when on main engine jacket water cooling.Perhaps you steam men out there can enlighten us motor heads on this strange phenomenae?


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## A.D.FROST

The only FW maker that was safe to run off the coast was a 'Tarpaulin' sheet.


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## BOB.WHITTAKER

Another popular rig based water maker was the "Aquachem " these were vapour compression units, very labour intensive and usually held together with Thistlebond and Jubilee clips . 
From my experience the worst ever was a Nyrex vacuum type on Gas Tanker MV Joule back in the mid 70's , another Thistlebond and Jubilee clip job . ( Both the ship and the water maker ) The best was a Weirs vacuum unit on MV Sir Alexander Glen , 30 - 40 tonnes per day no bother , we even ran a line to the aft peak to keep the unit online and ended up with over 900 tonnes of fresh water in there .


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## Derek Roger

funnelstays said:


> I was an on chemical tanker carrying inhibited styrene monomer.The main sea water overboard from the dump steam condenser sprung a substantial seawater leak which meant a steam shut down,as we could not use the cargo heating coils as they had to be blanked off for the carriage of the styrene.It was decided to use the steam side of the vap which had never been tried to substitute as the dump condenser.After a few hours of checking adjusting and fiddling it magically started producing fresh water at a greater rate and a lower ppm than when on main engine jacket water cooling.Perhaps you steam men out there can enlighten us motor heads on this strange phenomenae?


The Evap vacuum would be the same in both cases being produced by the ejector pump . Using the steam depending on flow and pressure you must have been supplying more heat to make more water than when using the jacket water . I don't understand however the lower ppm as generally when one tries to force an Evap its tends to prime to some degree causing a higher ppm .


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## alaric

BOB.WHITTAKER said:


> Another popular rig based water maker was the "Aquachem " these were vapour compression units, very labour intensive and usually held together with Thistlebond and Jubilee clips .
> From my experience the worst ever was a Nyrex vacuum type on Gas Tanker MV Joule back in the mid 70's , another Thistlebond and Jubilee clip job . ( Both the ship and the water maker ) The best was a Weirs vacuum unit on MV Sir Alexander Glen , 30 - 40 tonnes per day no bother , we even ran a line to the aft peak to keep the unit online and ended up with over 900 tonnes of fresh water in there .


J&G Weirs were at the leading edge of water making technology in the 1960s.
I was a Junior Engineer on Shaw Savill's Northern Star, and the following extract from my account of this ship's early machinery problems shows how good the Multi-Flash Evaporator was:

Weirs also supplied another significant piece, of what at the time was cutting edge technology. This was a 20 stage Flash Evaporator for making fresh water from the sea. In spite of being a prototype, this equipment really did work well, the water it produced was virtually pure and of the highest quality, and it made 500 tons/day of the stuff. It was so pure that it was virtually tasteless.
In 1962 it is was the largest capacity marine evaporator ever produced, and would still be regarded as big today, although I believe large modern fresh water generators are now of the reverse osmosis type rather than evaporators.


The evaporator was not brought into use until we were well clear of the coast, and it took quite some time to start up and produce good water, but when it settled down, there was no stopping it. There was virtually no control over how much water was produced, it was either the full 500tons/day or nothing! This was well in excess of the quantity normally used for ballast and hotel services, and even in the hottest weather it almost kept pace with demand. Usually, during the 4 to 8 morning watch, all the water tanks were filled, so the evaporator output was dumped onto the engine room tank tops and bilges until demand for water picked up again at breakfast time. On virtually every other steam ship of the time, the most precious substance (apart from beer of course) was good quality feed water for the boilers, and Northern Star used the highest quality water to keep the bilges clean. No ship afloat could compete with that! 

The Flash Evaporator was one of the success stories of the advanced machinery, and it gave little trouble during the first year of operation, although I do remember on V2 or V3 there was an occasion when due to some malfunction, the shell and tube heater scaled up and had to be cleared out manually.
In fact, had it been known in advance how well the evaporator performed, the boilers would probably have been fitted with steam soot blowers instead of the compressed air units actually installed.
In my experience, partly because of the higher pressures used, steam soot blowers seem to be more effective than air units. The big disadvantage is the quantity of steam, and hence boiler make-up they need. 
On Northern Star, the one problem never experienced was a shortage of feed water. It is ironic that the Boiler troubles which I believe were experienced throughout the life of the ship, could perhaps have been prevented or at least reduced if the ship had been equipped with steam soot blowers.


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## stoker

Re Alaric's post on SS Northern Star,
I did my tickets in the late sixties, the Northern Star and Southern Cross were much featured in the technical press at the time. In 1975 I was on the Dundalk berthed in Vigo when the Northern Star come in to the other side of the berth.
She was by that time a dying breed so I went on board to have a look. The Senior Second was good enough to show me the Engine room, I wanted to see the famous multi stage vap.etc. There I saw a crowd of Engineers struggling to remove a heat exchanger from this huge evaporator which seemed to take up half the engine room. Among them was a third whom I had sailed with in Ben Line, I seem to remember that he and his colleagues were less enamoured with this piece of equipment than Alaric was when he sailed on her, but she was near the end of her time with Shaw Savill in '75.
I googled Northern Cross on a Shaw Savill site and see the vessel listed as scrapped in '74. One of us has to be wrong.....38 years on it could be me, but I don't think so.
Evaps and the chemistry that goes with them is one area that improved out of all proportion since I first went to sea when the first thing you were asked when you handed over the watch was "how much water did you make?".


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## ccurtis1

Weirs evaporator on the Olivebank made 10 tonnes of good salt water every day as the blessed thing was forever "priming". Atlas FW generators were in comparison astro-physics


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## alaric

ccurtis1 said:


> Weirs evaporator on the Olivebank made 10 tonnes of good salt water every day as the blessed thing was forever "priming". Atlas FW generators were in comparison astro-physics


TWADDLE. It would likely have produced 8 tons/day of good water running at a lower density?


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## ccurtis1

alaric said:


> TWADDLE. It would likely have produced 8 tons/day of good water running at a lower density?


Not so dear boy. I was there and the Weirs vap required constant attention but still tended to prime and we were forever changing and chipping coils. Thank goodness for the Atlas FWG


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## alaric

ccurtis1 said:


> Not so dear boy. I was there and the Weirs vap required constant attention but still tended to prime and we were forever changing and chipping coils. Thank goodness for the Atlas FWG


I say again. TWADDLE.


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## Tony Morris

Does anyone remember having to go inside a Wiers Submerged Coil Evaporator to chisle out the salt build up - I was a lot thinner then!!


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## Duncan112

alaric said:


> I say again. TWADDLE.


Surely you mean Twaddel (Jester)(Jester)


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## ccurtis1

alaric said:


> I say again. TWADDLE.


I do not recall you being there, so I would guess that your comment is, to quote you, TWADDLE


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## alaric

Duncan112 said:


> Surely you mean Twaddel (Jester)(Jester)


No, I do mean TWADDLE.
You worried me for a minute, but have just done a google check and comfirm that TWADDLE or DT is at the heart of the matter.


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## alaric

ccurtis1 said:


> I do not recall you being there, so I would guess that your comment is, to quote you, TWADDLE


You are missing the point ccurtis1.
Perhaps you are more familiar with DT?


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## vickentallen

Used to use a Twaddel for taking the Specific Gravity of Acid (boat batterys) .. my twopence worth


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## ccurtis1

alaric said:


> You are missing the point ccurtis1.
> Perhaps you are more familiar with DT?


And what point are you alluding to? Please enlighten.
DT? Is that some form of illness caused by over-indulgence of alcohol?
I am sure readers of this thread will be agog with anticipation at your responses.


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## alaric

stoker said:


> Re Alaric's post on SS Northern Star,
> I did my tickets in the late sixties, the Northern Star and Southern Cross were much featured in the technical press at the time. In 1975 I was on the Dundalk berthed in Vigo when the Northern Star come in to the other side of the berth.
> She was by that time a dying breed so I went on board to have a look. The Senior Second was good enough to show me the Engine room, I wanted to see the famous multi stage vap.etc. There I saw a crowd of Engineers struggling to remove a heat exchanger from this huge evaporator which seemed to take up half the engine room. Among them was a third whom I had sailed with in Ben Line, I seem to remember that he and his colleagues were less enamoured with this piece of equipment than Alaric was when he sailed on her, but she was near the end of her time with Shaw Savill in '75.
> I googled Northern Cross on a Shaw Savill site and see the vessel listed as scrapped in '74. One of us has to be wrong.....38 years on it could be me, but I don't think so.
> Evaps and the chemistry that goes with them is one area that improved out of all proportion since I first went to sea when the first thing you were asked when you handed over the watch was "how much water did you make?".


Yes, "how much water did you make?" was indeed a feature of every steamer watch change I made, except on Northern Star.
Northern STAR arrived in Taiwan for scrapping in December 1975, Southern CROSS kept going (as Ocean Breeze) until 2004.
Pleased to hear you were made welcome on board for your brief visit to SSA.


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## Duncan112

Seems to be spelt both ways http://www.thelabwarehouse.com/laboratory-consumables/hydrometers/hydrometers-twaddel.html and just top add to the confusion with two ls http://en.wikipedia.org/wiki/Twaddell_scale


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## alaric

ccurtis1 said:


> And what point are you alluding to? Please enlighten.
> DT? Is that some form of illness caused by over-indulgence of alcohol?
> I am sure readers of this thread will be agog with anticipation at your responses.


The particular DT I was refering to is DEGREES TWADDLE, marked on the stem of the BRINE DENSITY hydrometer.
The correct use of this simple equipment, together with a thermometer and a temperature correction chart is the key to making good quality water without priming.
Why am I surprised you are not familiar with this DT?


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## Duncan112

Strangely, the only time I used DT at sea was for the brine density in the refrigerated cargo circuits, the brine hydrometer for the evap was calibrated in 32nds, explanation here http://www.tpub.com/engine3/en33-92.htm, the hydrometer always looked the worse for wear, no doubt having visited the bilges frequently and the fitted wooden box having been long mislaid.


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## alaric

ccurtis1 said:


> And what point are you alluding to? Please enlighten.
> DT? Is that some form of illness caused by over-indulgence of alcohol?
> I am sure readers of this thread will be agog with anticipation at your responses.


Your request for enlightenment is fully answered in Duncan112's link; http://www.tpub.com/engine3/en33-92.htm
I have nothing to add. Thank you Duncan


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## alaric

Duncan112 said:


> Seems to be spelt both ways http://www.thelabwarehouse.com/laboratory-consumables/hydrometers/hydrometers-twaddel.html and just top add to the confusion with two ls http://en.wikipedia.org/wiki/Twaddell_scale


TWADDLE, TWADDEL or TWADDELL?
Spelling of surnames does change over time, but I can find only TWADDLE in the Glasgow telephone directory, so I think I will stick with this.
Thanks for your input.
Do I see a Crusader shield?


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## Duncan112

You do - Crusader Swire Container Services on mv Chitral (ex Arafura, then Matilda Bay and P&ONL Tauranga)


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## ccurtis1

Still no enlightenment as to what point you are alluding to. My reference to DT was somewhat tongue in cheek, but perhaps a little too subtle for you.
The only Weirs Evaporator I came across was that on the Olivebank and it was scarcely used because of its unreliability. It was used on one voyage across the Pacific from Cairns/Townsville to St Johns, New Brunswick because the power that was on the bridge, dumped fresh water to load a few more tonnes of sugar and we left Australia with less than 20 tonnes of fresh water for all purposes.
The evaporator was less than efficient to say the very least and we were on water rationing across the Pacific and hunting rain storms. Never any such problems with Atlas FWG's and if Weirs were so efficient in your estimation, how come they were superceded by a much more efficient machine. More water of better quality and most definitely infinitely less maintenance


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## ccurtis1

Alaric.
I made some comment about an experiece I encountered a long time ago. I thought your reply ungracious and I responded ungraciously too for which I apologise. Lets agree to disagree about the merits of Weirs Evaporators and put this issue to bed.


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## howardws

In my experience if a Weir evap primed and you were keeping the brine density and brine level correct then removing the baffle in the top of the casing and soaking it in a solution of 'Saf Acid' and replacing it solved the problem. We did just this a few weeks after taking over 'Caltex Liverpool' from an Aussie crew in a Singapore shipyard sometime in 1978. We used to 'double distil' feedwater. First make your fresh water from the sea and then put it through a second evap to make feed. Cold shocking was always fun!


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## alaric

ccurtis1 said:


> Alaric.
> I made some comment about an experiece I encountered a long time ago. I thought your reply ungracious and I responded ungraciously too for which I apologise. Lets agree to disagree about the merits of Weirs Evaporators and put this issue to bed.


No need to apologise ccurtis1, I enjoyed our little skirmish.
The next time you hear anyone mention DTs, you will perhaps think of evaporators instead of the dreaded Delirium Tremens.


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## BOB.WHITTAKER

I was begining to think it was going to be " Handbags at ten paces "


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## actingjunior

I always remember the time we were on watch and the feed line (cast Iron) failed at the bend just before the evaporator. It had washed away over the years and we got our feet wet.
Naturally the feed pump was on the flat below the evaps, as the ship rolled the water cascaded down on top of the condenser feed pump ! Oh dear that didn't look good. I ran down to the lower flat to shut down the evap feed pump and was drenched by the water from the leaking pipe.
After the pump was shut down the 3rd engineer said I'd better go and tell the chief what had happened.
On arriving in the bar I was met with a howl of laughs and asked why I had gone swimming in my boiler suit.
Just as well we were around the line at the time, so the water wasn't to cold !


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## eriskay

*Fresh Water Makers*

As an employee of the Weir organisation for 45 years, prior to that seagoing on steam tankers for four years, and prior to that over five years in ship repairs, I have been directly involved in Desalination, primarily Multi Stage Flash and other thermal processes, for almost half a century so found the content of this thread interesting. Until now I have not responded as I too thought it might well be heading toward 'handbags at ten paces' .... !

All I would like to point out is that whereas the Distilling processes are fundamentally the same, and by and large the Evaporator Units are similar in construction and choice of materials, the main reason for mal-performance and inefficiency in output and/or product quality is associated with the operation, and maintenance, of the equipment.

Thermal systems are generally reliable if understood and worked as intended, whereas process such as SWRO and BWRO tend to be more fickle and temperamental and affected by external variables such as the quality of the raw feedstock.

My seagoing experience was Caird & Rayner S.W. Evaporator Units with the product final-polished via a Weir Evaporator. Good system, not too many problems, albeit chipping coils was a bit of a pain !


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## alaric

Having accepted the gracious apology by ccurtis1 I feel I must make a confession of my own.
All the ships I sailed on, with one exception, used standard hydrometers calibrated in 1/32s for measuring evaporator brine density. The exception was either Corinthic or Athenic (can't be sure which) which always used the TWADDLE scale. I guess because the hydrometer had strayed from the refrig. engine room to the main engine room.
But the word itself is so attractive, I couldn't resist introducing it into the thread.


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## waldziu

When I was an "Evaporator Operator" on HMS Rothesay circa mid 70's whilst on exercise in the Baltic The Deputy Engineer on his evening rounds questioned me about the brine density reading on the Evap log sheets. I endeavoured to explain but he was not having it and instructed me to take a sample. I drew off a sample and nonchalantly tossed the hydrometer (Twaddle) and thermometer into the sample and they both hit the bottom....and that is when he comprehended that the Baltic has a very low salinity level. Book engineers I s***t em.


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## jep1916

*FW Generators*

I was serving on board the British Resolution doing lightering operations off the coast of Panama. We were producing our own fresh water using the on board FW Generators. However, the water made was never dosed with the correct chemicals to beat the bacteria produced and two of the engineers went down with jaundice / hepatitis. 

The 20 mile limit advisement was to try and eliminate the possibility of bacteria entering the ship's water supply due to the low boiling temperature of the FW Generator.

Making water for boiler use didn't present any problems, you could make it where ever you liked.


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