|
|
Post by chris vine on Jan 29, 2021 11:27:12 GMT
I was given a maintenance tip for injectors:
After a run, squirt WD40 up the overflow so the injector is full of that instead of water which can precipitate onto the cones etc.
Unfortunately for me, it took a bit of work to make sure the boiler clack valves didn't leak when cold, as that just washed out the WD40.
Roger's tip to use silicon nitride balls was a good one. Although it took a bit of a squeeze to get them to from a seal in the conical (originally for Viton balls) seat in PB102!!
If you let the overflow run for a few seconds before use, the WD 40 runs onto the ground rather than being pushed into the boiler.
Chris.
|
|
|
|
Post by Roger on Jan 29, 2021 12:14:29 GMT
This is a development of the most successful cone which had 10 x 0.6mm holes and 4 x 0.5mm holes. This is intended to see if approximating to straighter edges of the cone ends will help. To that end, this now has 12 holes in each position. Now these holes overlap so slightly, I really ought to be drilling them differently, because although the holes start in virgin material, they soon enter the space cut on one side by the previous drilled hole. To that end, I've chopped the 12 holes into three operations. First I drill three holes, then another three, offset by 60 degrees, followed by another 6 at 30 degrees. The idea is to end up cutting each hole into either virgin material or have the same hole feature to break into on either side of the drill. I'd already drilled the Delivery overflow holes before thinking about this, but I've done the Combining holes. that way.  Cone21 by Georgia Montgomery, on Flickr I can't go further without making the neck diameter larger because there's not enough material left and I'll end up with three parts! I might make one with a 4.5mm neck. Doing that allows 18 holes which gives a really good approximation to a straight edge.  Cone22 by Georgia Montgomery, on Flickr |
|
|
|
Post by dhamblin on Jan 29, 2021 13:01:16 GMT
Silly question Roger - are you creating the cone first during machining and then drilling the cross holes? Just wondering if there are any small burrs left by this that may have a further effect on turbulent flow, although I recall you were looking at this earlier during the experiments.
It is indeed frustrating that you cannot actually see what is going on inside the injector during each test.
Regards,
Dan
|
|
|
|
Post by Roger on Jan 29, 2021 14:02:02 GMT
Silly question Roger - are you creating the cone first during machining and then drilling the cross holes? Just wondering if there are any small burrs left by this that may have a further effect on turbulent flow, although I recall you were looking at this earlier during the experiments. It is indeed frustrating that you cannot actually see what is going on inside the injector during each test. Regards, Dan Hi Dan, I drill the pilot hole through the centre of the cone first. Then I drill all of the cross holes. Finally, I ream the tapers. I poke through the radial holes with Florist's wire, and then just gently spin the reamers by hand in the holes to make sure I haven't pushed a burr into the holes. I can tolerate burrs in the overflow holes as long as they aren't too big, but not in the tapered bore. |
|
|
|
Post by Roger on Jan 29, 2021 21:04:40 GMT
I think it's time to see if I can translate the performance I'm getting on the Development Injector to the scale body. Before doing that, I wanted to change the overflow valve to the same type as I've got on the Development Injector. So here's one made from Brass just to quickly try it and find out what dimensions it needs to be to get the right spring pressure and travel.  20210129_165343 by Georgia Montgomery, on Flickr So all I've done it to change the valve and make a spacer for the Steam Cone that I already have, just to give it a try. I also had to make a spacer for the delivery end so that when the end cap is screwed up to the stop, there's compression on the axial O-ring. Anyway, I had quickly switched this on to make sure it would actually pick up, but that's all. I thought I'd post this first test so you can share the trials a tribulations of this journey.  20210129_203649 by Georgia Montgomery, on Flickr So, what have we just seen? Everything looked ok until we reached what looked like 72psi where the first signs of trouble showed, and then it gave up at 65psi. Then it wouldn't behave even if I restricted the water. Obviously this isn't satisfactory, but it's a million miles better than it was when I decided to make the Development Injector. Actually, I'm rather pleased that it did this well, it's not far from working. So what are the differences between this and the test setup? 1) The regulation gap might be slightly different, I've set it as close to the size I think it should be, but the instability is what I've seen many times when I have had it too small. 2) The Steam Cone is 1mm not 1.05mm which is what it was last tested with. I need to increase the size of that. 3) The Steam Cone doesn't have a tapered hole in the back, it just comes to a drilled 120 degree cone before the parallel section at the throat. 4) The overflow valve definitely has more spring compression when the valve is closed. 5) The Steam Inlet is slightly more restricted. 6) The pipework and internal flow arrangements are obviously different. I now need to work my way through these and try to progress towards the same performance I was getting on the Development Injector. Hopefully that won't be too difficult to achieve. |
|
jma1009
Elder Statesman
Posts: 5,922
|
Post by jma1009 on Jan 29, 2021 21:47:09 GMT
Re the performance of the DAG Brown injectors as performance criteria, I can confirm this criteria, and it is apparent in the medium standard injectors of Arthur Grimmett, Ted Linden, and Gordon Chiverton. Gordon's smaller injectors also satisfied this criteria.
I totally disagree that an injector that feeds below 40psi is not required, but then I've never fitted a hand pump to wank away at.
The ultrasonic cleaning tank is the way to go if you have to clean an injector. Scale should not build up in an injector.
Never squirt WD 40 into the injector overflow.
|
|
|
|
Post by Roger on Jan 29, 2021 22:30:01 GMT
Re the performance of the DAG Brown injectors as performance criteria, I can confirm this criteria, and it is apparent in the medium standard injectors of Arthur Grimmett, Ted Linden, and Gordon Chiverton. Gordon's smaller injectors also satisfied this criteria. I totally disagree that an injector that feeds below 40psi is not required, but then I've never fitted a hand pump to wank away at. The ultrasonic cleaning tank is the way to go if you have to clean an injector. Scale should not build up in an injector. Never squirt WD 40 into the injector overflow. Hi Julian, That's good to know. I just thought that some working down to 15psi might have been misleading. I'm sure you can achieve this sort of thing if you have feed water at 10C but I'm surprised they work that well at 20C. I can't say I've ever needed an injector to pick up below 40psi on any occasion. There's no argument to say it's a bad thing, I just don't think it's necessary. I won't have a hand pump either, but I can't say I'm going to lose any sleep over it. |
|
jma1009
Elder Statesman
Posts: 5,922
|
Post by jma1009 on Jan 29, 2021 23:51:19 GMT
Below 40psi...
So, you have a full train load of punters, and you've done 2 laps with them stopping at the station for the next load of punters queuing up in a long queue.
You've got probably the bottom row of tubes blocked because you've been running the loco for 4 hours or more passenger hauling, and the coal is not the best quality.
It is redeemable - you don't want to disappoint the punters and the kiddies who want to have a ride behind a real live steam miniature loco instead of behind a substitute electric battery contraption - so at 30psi or even 25psi you whack on the blower, refill the tender or tanks to give you a bit of time to recover. And you put one of the injectors on as the gauge glass level is low.
The fire, carefully managed perks up, as does the water level in the glass and when you have prevaricated a bit further by a quick oiling round, you are ready for a further 2 laps non stop with your paying punters that keeps the club solvent, and you haven't disappointed any of the kiddies who wanted a ride behind a real miniature steam loco.
|
|
|
|
Post by Roger on Jan 30, 2021 9:16:58 GMT
Below 40psi... So, you have a full train load of punters, and you've done 2 laps with them stopping at the station for the next load of punters queuing up in a long queue. You've got probably the bottom row of tubes blocked because you've been running the loco for 4 hours or more passenger hauling, and the coal is not the best quality. It is redeemable - you don't want to disappoint the punters and the kiddies who want to have a ride behind a real live steam miniature loco instead of behind a substitute electric battery contraption - so at 30psi or even 25psi you whack on the blower, refill the tender or tanks to give you a bit of time to recover. And you put one of the injectors on as the gauge glass level is low. The fire, carefully managed perks up, as does the water level in the glass and when you have prevaricated a bit further by a quick oiling round, you are ready for a further 2 laps non stop with your paying punters that keeps the club solvent, and you haven't disappointed any of the kiddies who wanted a ride behind a real miniature steam loco. I'm sure you can dream up situations where it would be helpful for an injector to pick up at 25psi. However, it's never been a problem in the few years I've driven fully loaded trains non-stop at fetes or anywhere else. I'm not saying it can't happen, but it's never happened to me. I'm not trying to make the case against low pressure working, there isn't one. However, I'm not convinced that it's a big deal. If you've only got 25psi on the clock, putting on an injector is going to kill the little pressure you've got, and you'll be back on an electric blower in no time. Waiting a couple of minutes for the pressure to come back, even if you're on the bottom nut with the water is a better strategy in my opinion. Don't forget that I've got an axle pump, so as soon as the locomotive is on the move, it's easy to get water in the boiler. I'll certainly try to get the injectors to work as low as possible, but it's not a deal breaker. |
|
Gary L
Elder Statesman
Posts: 1,208
|
Post by Gary L on Jan 30, 2021 13:34:57 GMT
Below 40psi... So, you have a full train load of punters, and you've done 2 laps with them stopping at the station for the next load of punters queuing up in a long queue. You've got probably the bottom row of tubes blocked because you've been running the loco for 4 hours or more passenger hauling, and the coal is not the best quality. It is redeemable - you don't want to disappoint the punters and the kiddies who want to have a ride behind a real live steam miniature loco instead of behind a substitute electric battery contraption - so at 30psi or even 25psi you whack on the blower, refill the tender or tanks to give you a bit of time to recover. And you put one of the injectors on as the gauge glass level is low. The fire, carefully managed perks up, as does the water level in the glass and when you have prevaricated a bit further by a quick oiling round, you are ready for a further 2 laps non stop with your paying punters that keeps the club solvent, and you haven't disappointed any of the kiddies who wanted a ride behind a real miniature steam loco. I'm sure you can dream up situations where it would be helpful for an injector to pick up at 25psi. However, it's never been a problem in the few years I've driven fully loaded trains non-stop at fetes or anywhere else. I'm not saying it can't happen, but it's never happened to me. I'm not trying to make the case against low pressure working, there isn't one. However, I'm not convinced that it's a big deal. If you've only got 25psi on the clock, putting on an injector is going to kill the little pressure you've got, and you'll be back on an electric blower in no time. Waiting a couple of minutes for the pressure to come back, even if you're on the bottom nut with the water is a better strategy in my opinion. Don't forget that I've got an axle pump, so as soon as the locomotive is on the move, it's easy to get water in the boiler. I'll certainly try to get the injectors to work as low as possible, but it's not a deal breaker. Not a major issue either way, but a pump is a bigger killer of boiler pressure than an injector due to feeding (relatively) cold water. As someone (Julian I think) pointed out earlier, the injector will only feed a dribble at low pressures, but if your water is close to the bottom nut, that is what you need. A flood of cold water wouldn't help. Having said that, Julian is a better driver than I am, if he can pull back from the situation described before the punters get bored and drift away! Gary |
|
|
|
Post by Roger on Jan 30, 2021 20:37:28 GMT
I've played around with a few spacers and a new Steam Cone today but without really learning much. So rather than waste lots of time on that, I thought I'd modify the scale injector design to make the regulation gap adjustable. It still retains the scale appearance, but the green flange is not part of a diameter that goes inside the blue end cap. The grey spot in the middle of the green part is a separate plug that's permanently attached and faced off so it doesn't show.  Adjustable injector by Georgia Montgomery, on Flickr And this is what's inside. The flange on the blue part goes in up to the body face so that the cutouts for the steam and water can be machined where they line up. This solves a problem I had with the original design where I ended up making a basket type of spacer because I couldn't guarantee where it end up, and might block the inlet. So the end stop for the One Piece Cone is the end of the blue piece.  Adjustable injector sectioned by Georgia Montgomery, on Flickr The Green part is threaded M5 x 0.5 (fine) to the right of the steam inlet, and the whole cone moves in or out from the position shown. The only thing I'm not that pleased about is the 0.5mm section O-ring on the steam cone for the inner seal. However, I can't see a way to use a 1mm section one at the moment. I may see if I can shoehorn that in and sacrifice a little of the water inlet cross section. We'll see. Anyway, this will make experimenting much easier. It will let me find the sweet spot quickly for any setup and let me explore the effect of the internal arrangement at the outlet end including the clack.  Adjustable steam cone by Georgia Montgomery, on Flickr |
|
jma1009
Elder Statesman
Posts: 5,922
|
Post by jma1009 on Jan 30, 2021 21:39:29 GMT
Hi Roger,
I didn't "dream up" that "scenario".
You ought perhaps to look again at the Roy Amesbury design of injector that he described for his 'President' GWR ex French loco in 5"g in ME in the early 1980s.
Cheers,
Julian
|
|
|
|
Post by chris vine on Jan 30, 2021 21:53:50 GMT
Hi Julian,
I am interested in your comment on WD40.
Why is it a bad thing to put it in an injector?
Thanks
Chris.
|
|
|
|
Post by andyhigham on Jan 30, 2021 21:56:16 GMT
Because it will get into the boiler, contaminating the water and priming issues
|
|
|
|
Post by coniston on Jan 30, 2021 22:02:53 GMT
Just as an aside Roger, I see you must be using a Tannin scale and corrosion inhibitors in the water judging by the colour of it, I guess to prevent rusting of the boiler? Dad once convinced me to try some Multitreat TC in my Simplex, after about half hour in steam the injector completely packed up adn I had to retire to the steaming bays to clean it out, even then it took a couple of future steamings with only plain water to get it working dry again. I'm not saying it was entirely the fault of the treatment, it may be have been complete coincidence or the treatment may have disturbed something else in the boiler but since then I have never used that treatment in a copper boiler and never had any problems. Just to be clear the boiler had been descaled a couple of months before and steamed on several occasions between the descaling and the incident.
My point is that as your 1501 has a copper boiler and presumably you wont be needing the treatment then would it be useful to run some test with plain water? or maybe soft water depending on what you intend to run with?
as I said just a thought.
Chris D
|
|
|
|
Post by Roger on Jan 30, 2021 22:07:31 GMT
Just as an aside Roger, I see you must be using a Tannin scale and corrosion inhibitors in the water judging by the colour of it, I guess to prevent rusting of the boiler? Dad once convinced me to try some Multitreat TC in my Simplex, after about half hour in steam the injector completely packed up adn I had to retire to the steaming bays to clean it out, even then it took a couple of future steamings with only plain water to get it working dry again. I'm not saying it was entirely the fault of the treatment, it may be have been complete coincidence or the treatment may have disturbed something else in the boiler but since then I have never used that treatment in a copper boiler and never had any problems. Just to be clear the boiler had been descaled a couple of months before and steamed on several occasions between the descaling and the incident. My point is that as your 1501 has a copper boiler and presumably you wont be needing the treatment then would it be useful to run some test with plain water? or maybe soft water depending on what you intend to run with? as I said just a thought. Chris D Hi Chris, Yes, it's just for the Steel boiler, I won't be using any in the Copper one. This stuff doesn't seem to be clogging things, so maybe it's different to the one you used. |
|
|
|
Post by Roger on Jan 30, 2021 22:42:54 GMT
Hi Roger, I didn't "dream up" that "scenario". You ought perhaps to look again at the Roy Amesbury design of injector that he described for his 'President' GWR ex French loco in 5"g in ME in the early 1980s. Cheers, Julian Hi Julian, The only thing I've got of Roy Amesbury's is the article with the title 'Amesbury injector improvements'. I don't think I've see the design you mention. |
|
|
|
Post by keith1500 on Jan 30, 2021 23:03:26 GMT
All this talk about whether or not an injector should work below 40psi;
Don’t loose sight of the upper limit. For there is a worst case scenario to endure where your locomotive has performed well, you have good fire and a low water level. The safety valve lifts but the injector doesn’t want to work and your water level is going down fast.
Fascinating work. Interesting drawings and you are much braver then me sharing your trials and tribulations ....
Keep up the good work.
Cheers
Keith
|
|
|
|
Post by David on Jan 30, 2021 23:07:22 GMT
you are ready for a further 2 laps non stop with your paying punters that keeps the club solvent, and you haven't disappointed any of the kiddies who wanted a ride behind a real miniature steam loco. Or you can go into a siding so you don't risk stalling halfway around the run and holding everyone up and let the next real miniature steam loco take the passengers. Most drivers aren't good enough to do what you're suggesting, and most clubs (for now) won't have just the one steam loco in a pack of electrics. Our club is changing, but most passenger days we still have almost all steam locos going except right at the start and end of the afternoon. I don't have a hand pump on my loco (or the nearly finshed mogul) but the world doesn't end if I have to slink off the mainline to get things back together before the next run. I just say I wanted a coffee. Even if I did have a pump I wouldn't be using it at 40psi other than to get enough water to see at the bottom of the glass and make steam with - I wouldn't be pumping up like mad for the next run. As for pumps in general, for some reason my club has much the same attitude towards any sort of pump you do. Given the potential for unreliability injectors present (and that I have suffered from for years because neither I nor anyone else figured out the cause until last year) I'm baffled by this. If I could be bothered to fit it I'd love an electric pump in the tender. You can't use the purism card because even though these small locos work about the same as a real one, there are compromises of every size and type everywhere on them. |
|
|
|
Post by Roger on Jan 30, 2021 23:17:12 GMT
All this talk about whether or not an injector should work below 40psi; Don’t loose sight of the upper limit. For there is a worst case scenario to endure where your locomotive has performed well, you have good fire and a low water level. The safety valve lifts but the injector doesn’t want to work and your water level is going down fast. Fascinating work. Interesting drawings and you are much braver then me sharing your trials and tribulations .... Keep up the good work. Cheers Keith Hi Keith, So far, the high pressure end hasn't been a problem in the development setup, but it's not the same as the scale body which has some severe limitations as to what you can do. The 8x injector is only 8mm diameter on the outside, it's much smaller than the usual 10x type. It's easy to do everything behind the scenes and pretend it was all plain sailing, but it wouldn't be honest. I think it's much better to share the thinking along the way, then we can all learn something from the experience. It also means that I can benefit from observations that others make. |
|
