Injectors

[ron]

Hi Everybody
Just found another piece of kit I know nothing much about apart from how it work-----the injector. If I was to buy a commercial one for Simplex what size should I look for and does it make any difference, other than locating it whether it is horizontal or vertical.
Cheers
Ron

[John Lee]

It really depends on whether you are relying on injectors alone (in which case you really need 2) or you are using the as designed axle pump.

I would guess the latter; something about 24 oz/minute size would do the job, as you are only likely to be using it when stationary and not consuming much steam.

If no axle pump then 2 injectors (in case one fails if for no other reason) and use full size practice, one large and one small, something in the 40 oz range for a quick fill, and a small one (you decide, pipework sizes will probably decide it for you) for minimal steam consumption that you can leave on for a while without killing the pressure when running.

Experience of the latter with a "Butch", which is more or less the same size, just a bit heftier. Others mileage and preferences may vary.

Regards,

John

[ron]

Hi John
I was intending using the 'improved' axlepump, I've bought the castings, plus an emergency hand pump, I've drilled the boiler for 3 clacks, two at the front and one on the backhead.
Ron

[greasemonkey]

Hi Ron
Johns advice is good but I wouldnt go as large on the injectors capacity. A 40oz injector needs 1/4" pipe and on a Simplex I think you will find that to large, the bushes would need to be threaded 3/8X??? so the OD's are getting on for 1/2 inch plus. I would use an 11oz injector myself just to assist in keeping the level up when running if the pump cant cope (it should, most simplex pumps when reasonably built over supply) or a 22oz that will do it all. Injectors have a certain range of working and if your presure falls bellow this they can be awkward to 'pick up' so I would definately keep the hand pump.

Andy

[chris vine]

Hi Ron,

Once you get the hang of injectors, you will never want to use an axle pump again.

But as the others say, if not using a pump you should have 2 injectors. It is a good idea to make sure that, even if different sizes, that the unions are the same. Then you can keep one spare which will fit either side.

The beauty of an injector is that it is essentially 100% efficient. If it uses more steam than is really necessary, the feed water is just that bit hotter so there is no waste.....

Very Scottish ha !

Chris

[havoc]

Normal 1:1 practise was to have 2 identical injectors and to use them alternatively (to make sure they both work). Problem with injectors is that they can be temperamental and are sensitive to deposits. So if you doesn't want to work immediately you can switch to the other and it has enough capacity. Also if you keep a third you can place it anywhere and don't have to worry about capacity.

[SteveW]

Guys,

I occurs to add that if the feed water gets too warm they can stop working. If the feed water is from either saddle or tanks adjacent to the boiler and the day is warm you may have a problem.

Frequent top-ups with cold water help but once it starts you'll need to go mechanical to keep going.

[Shawki Shlemon]

Hi all
One point was not mentioned about injectors and that is one must ensure there is no air in supply line as well as all the other points. Water supply is essential to the operation of the boiler, the method we pump it in may vary from axle pump,hand pump , injector, to steam pump . All these methods have advantages & disadvantages but I personally prefer to have at least two different methods on all my engines .Injectors are good with tender engines, axle pumps work all the time if you are moving , hand pumps one may never need them but they give the feeling of confidence in an emergency when all other systems fail .We may argue which system is the best but in my opinion it is a matter of personal choice .

[houstonceng]

Shawki

Under the new boiler testing regulations for UK Models, there MUST BE TWO methods of topping up the water (Pump+injector, two injectors, etc)

What does the Oz (AALS ?) regulations require ?

Andy

[ron]

Thanks for the replies, from what has been said it looks like I should connect the injector to the water tank at the rear of the cab as it has cool water and the axle and hand pumps to the two side tanks.
I've had experience of full size injectors in industry years ago, they were a bit temperamental which has probably made me a bit wary of model ones, but from what has been posted it looks like they are OK if they are set up correctly.
Ron

[Steve M. W]

Hi Ron

I favour leaving the rear tank out on my Simplex and feeding the injector from a remote tank on the driving truck this leave the side tanks for the Axel pump and hand pump.
The injector water from the driving truck is always cold so should feed better.
I have driven a friends loco (very similar to Simplex) with this arrangement and it works very well, he has a small rear thank but uses that to feed a second injector but we rarely use that, we can stay out for 30+ laps of our raised track non stop just using the remote water now that’s fun keeping the balance going between coal, water and steam pressure on the move.

Steve

[baggo]

I'll second Steve's idea of feeding the injector from a separate tank on the driving trolley. That's what I'll be doing for my 2½ gauge tank loco. Even on Simplex the capacity of the rear bunker tank is very small and if you fit the balance pipes to the side tanks you will be drawing the warm water from them into the rear tank as fast as you take it out with the injector.

John

[Shawki Shlemon]

Hi Andy
To answer your question I will type the paragraph from the code.
5.4 FEED WATER SYSTEM
5.4.1 Boilers for locomotives, traction engines and other mobile applications shall be equipped with at least TWO (2) independent means of supplying feed water. These may be in form of injectors,mechanical pumps, steam pumps,hand pumps, or any other method capable of supplying enough feed water to maintain the boiler water level under normal operating conditions.
Stationary and marine boilers shall be equipped with at least ONE (1) feed water supply system.