Steam Injectors

[mtnman]

OK I've been looking at pictures, pictures and more pictures of Launch boilers. Now I have a question, Why don't Marine boilers use steam injectors to keep the boiler full? All steam traction engines use injectors as do most all stationary steam engines. Out of hundreds of marine boilers I've looked at only a couple use injectors, why? I plan on using a ½ Penberthy AA528 for my main pump, bought it a couple of weeks ago on ebay. I should say I stole it as I only paid $177 and it's NOS, never used.

[Edward]

Dear mtnman,

They do , or at least a very large number do . Of course there may be a difference in the numbers involved between North America and elsewhere but at a guess roughly half of British launches have injectors as well as pumps .
They are quieter than pumps (although this advantage is nullified if you have a pump as well ) and if set up properly are very reliable .
All pipe runs for injectorrs must be as straight as possible with any curves/corners as gentle as possible . It's also advisable to mount even a lifting injector as near to the water level as practical though it's certainly not necessary to have them permanently flooded . They don't like having hot feedwater as when they suck at it the reduced pressure can easily cause the feed water to boil prematurely ; feed should also go through some sort of strainer /coarse filter as bits of weed etc can also stop them .
Penberthys are considered to be easily the best though Buffalo are also good . When buying it is essential to get the injector suited to your pressure range and also to make sure you are getting a lifting injector.

There are those who swear that to get an injector to work it is essential to use the right incantations while sacrificing black cocks on a crossroads at the full moon at midnight : though this undoubtedly helps these people are uneccessarily pessimistic .

Regards Edward .

[farmerden]

I have a steam injector on the "Steam Queen" ,there is also a boiler feed pump [displacement style],and a hand pump.The injector works great but I did replace the valve to it because it was leaking just enough to keep the injector warm and it would not lift-sure I could pour a bucket of cold water on it which cooled it down then it worked but that looked kinda haywire so I replaced the valve and it works every time! Also a steam injector uses steam [It's amazing what you learn here isn't it ] Quite a bit of steam -now that's ok when you're tied up at a dock but I always seem to be late for somewhere and need all the steam for the engine! I think the displacement pump run by the engine is the more efficient way of keeping the boiler topped up.Because my extra water tanks are down in the bilge it is only then that I use the injector to lift that water [either to the boiler or the hotwell] The bonus of using an injector however is that the water you put in the boiler quite warm so your boiler comes back up to operating pressure quicker than pumping cooler water in. Does that help or did I wander off topic? Den[/img]
As an aside you will notice the boiler pressure is only 60psi I had probably added water from the hotwell.Also notice the feedwater heater at the back of the engine left side,then follow the black pipe up the left side of the firewall and eventually into the boiler. Ask me why that line leaves the feedwater heater,runs along the boat bottom in the cold bilge water ,then up the firewall etc. Sounds counterproductive doesn't it? Nobody said I was perfect,I have a list of to-do things for the boat but unfortunately I also have a Honey-do list and you know what list has priority!!
click on the picture-it's a video Den

[steamboatjack]

Hi,

Just to follow on from the comments above, It really depends where you expect to get your feed for the injector from, most users in the UK are puffing so they take feed straight from the lake/river, this is ok as its cold. if taking from a feed tank ok but is taking from the hotwell you may have problems. hotwells should be HOT about 80-90C is good but rarely achieved (less oxygen in the water is the advantage as well as heat conservation).
If you are condensing I would suggest a good alternative would be to use a pump from the hotwell and an injector from overside or a separate feed tank if you are on salty water. This would then provide make up feed which you always need with the best of systems.
Boiler blowdown is the best way to operate and conserve a boiler so you need a good make up feed supply.

Regards
Jack

[dhic001]

On most boats here in New Zealand, and certainly on my own, Zeltic, the injector is used as the secondary feed. Primary feed is done by the engine driven feed pump, with a bypass valve just before the check valve. The advantage of that system is that you can continually add a small amount of feed water while underway, to compensate for that being used. Well set up on a long run, the feed can be set so exactly that the bypass doesn't need touching for hours. Injectors are lovely, and I wouldn't be without one, but even a small unit bangs a lot of water into the boiler, which can knock your steam production very quickly. Remnember that locomotives are constantly changing their steam use, due to speed restrictions, gardients etc, those variables rarely apply on a boat, so the constant feed of a engine driven pump is well suited to the more constant running speed of a marine engine.
Daniel

[87gn@tahoe]

^ what he said

[mcandrew1894]

What they Said!

I use a Superscale Locomotive works "Economy" injector on my boat as a secondary feed source from either the feed tank or from the water I'm in. I didn't plumb it to the hot well for reasons stated by John.

It works well. Great way to simmer down a boiler when you slide into your slip with a bit of a fire.

Dave

[farmerden]

Ditto on that Dave! It's amazing what one learns on the way to becoming a steamer.I once was pulling into Sidney to clear customs and not wanting to come in with too much heat I shut down the fire coming into the breakwater-Yup you guessed it-I ran out of steam and had the channel plugged while I refired the boiler [Dumb rookie!] Now I can come in strong, full of steam and use the injector to use excess steam ,cool down the boiler ,and fill everything up! And all those infernal combustion guys aren't throwing stuff at me for plugging the channel! Den[/img]

[Edward]

About 20 years ago an SBA member , Robin Wallace-Sims , was with his wife Mary in his boat ELIDIR on the Thames .
At one of the locks he decided to inject as the safety was about to blow , he was leaning forward and so was out of touch with those on the lock side . Mary was talking to a Spanish person who was taking a close interest and lots of photographs who asked her what was going on . In a not very scientific manner but not inaccurately she explained that : " ..the boiler is overheating and he is cooling it down by injecting cooler water ."
They continued talking and it transpired that the Spaniard was taking notes and photographs for a kit model steam launch planned by a Spanish company .
A couple of years later the model appeared on the market ; it wasn't too bad but in the background notes and history on the side of the box it read : " The 19th Century steam launch reached its peak of development on the River Thames in England where they even featured water-cooled boilers ...."

Regards Edward .

[Dhutch]

We also use steam injectors on Emilyanne.

The majority of the feed water is managed with a self-regulating three-ram engine driven pressure washer pump, but with have a pair of small-sized injectors that can be used singularly or in in tandem to lift additional water into the boiler or when the engine is not running. They are small enough, and prehaps not ideally maintained so tend to be some what intermittently reliable compared to the pump but typically one or other can be got to work at any one time.


Daniel