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| Non lifting injector won't continue to hold... diagnosis? https://www.rypn.org/forums/viewtopic.php?f=1&t=31111 |
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| Author: | JohnHillier [ Sat Mar 26, 2011 9:01 pm ] |
| Post subject: | Non lifting injector won't continue to hold... diagnosis? |
First off, I didn't write down what manufacturer injector this is but I will fill it in when I get the chance. Basically everything picks up and starts to run just fine, but after about 2-3 seconds the overflow lets out whatever is not being pulled in... which is the problem. I've blown back the feed valve, pulled out the nozzle and cleaned it, and removed all the checks and inspected them with out problem. Any ideas? Warm water is also not the issue... nice and cold. |
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| Author: | John Deck [ Sat Mar 26, 2011 9:11 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
What size injector is this? There are a number of issues that could be causing your problems. You have addressed the obvious ones like dirt in the injector, check valve problems, hot water, what you need to look at is the check on the injector that is in the overflow. If it is worn it will not allow a vacuum to form and the injector will slobber or not pick up at all. Have you tried various combinations of steam/water flow? I know on Penberthy injectors if you do not adjust your steam and water flow they will slobber. |
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| Author: | DBH [ Sat Mar 26, 2011 11:18 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Did you check the feed strainers to see if they are clogged? Dave Huffman |
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| Author: | Nigel Anthony Hewer Day [ Sun Mar 27, 2011 3:16 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Try checking for air leaks and holes in the pick up pipe, it causes a loss of vacuum and the air drawn in prevents the full action of the injector cones. If there are cones which come into contact and for a seatings inside the injector when it picks up these must be inperfect condition. Any seals on the cones must be good or repaired/replaced. Remember the cones do wear out and become groved and pitted inside, in such instances the serface even when polished will show scratching which prevents the full velocities requiered being achived, here only replacing the cones will work. Never use anything realy abrasive on a cone. |
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| Author: | DBH [ Sun Mar 27, 2011 4:16 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
A non lifting injector is below the bottom of the tank so you are not worried about air leaks in the suction line. If there was a leak you would see the water leaking out on the ground when the injector is shut off. Dave Huffman |
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| Author: | Nigel Anthony Hewer Day [ Sun Mar 27, 2011 4:37 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
True,I admit that I wrote the coment in general terms for all injectors. I have seen non lifting injectors where the water valve is say on the tender and then conected to the loco by a rubber hose to the injector. The hose was slightly holled but not enough to show water and that was enough to affect the injector. I have also seen one off take from the tender feeding two items say a feed pump and injectors also cause problems with the difrent pressures and flow rates in the feed pipe work. |
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| Author: | J.David [ Sun Mar 27, 2011 10:26 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Hi John: A few thoughts: Are you certain that the boiler check valve is opening fully? Look inside the tank hose to see if the lining is loose or torn. Either could allow full flow until the injector begins forcing. Has the injector been recently re-piped or had a new steam valve installed? Insufficient steam flow could be an issue. Steam lines to injectors should have no elbows, tees, etc. and the steam valve at the turret shouldn't be of the globe valve type, these too restrict the flow. Does the injector on the other side of the locomotive function properly? Good luck! J.David |
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| Author: | JohnHillier [ Mon Mar 28, 2011 10:32 am ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Both injectors function and are tested daily however the engineers side steam leaks at the valve so it remains off until needed. I drained the tender and climbed inside to check the strainer which had a few paint chips but nothing to inhibit water flowing normally. The tank hose is also relatively new and not kinked. Boiler pressure also does not seem to affect the issue. There is a ball valve back up to the boiler checks in case of one of the checks failing to seat. There is also a drain valve on the delivery pipe itself which I often check with the injector not running and back up check valve open and find no pressure after the initial spurt of water when it is opened. Having said that I have a couple ideas on what the issue might be but won't get to work on them til tomorrow. Thanks for your help. |
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| Author: | DBH [ Mon Mar 28, 2011 11:06 am ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
One thing that comes to mind is your steam pressure matched to the injector. You may need to throttle the water supply down some to keep the injector running. DBH |
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| Author: | Dave [ Mon Mar 28, 2011 12:44 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
I'm confused. How can water that was not pulled in to the injector appear at the overflow? Also, some description of whether it is a lifting or nonlifting installation would be beneficial. The "pulled in" suggests lifting, but since it doesn't make sense in the first place........knowing what model of injector it is would also help narrow down the possibilities - for instance, if it has a seperate priming valve that leaking steam might cause loss at the overflow. Question: does the injector deliver while it wastes water, or does it break delivery entirely? dave |
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| Author: | DBH [ Mon Mar 28, 2011 1:20 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Dave, they are dealing with a non lifting injector. Yes it would be nice to know the brand & model to helpgive useful information. Guess we will have to wait for that info. DBH |
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| Author: | JohnHillier [ Tue Mar 29, 2011 6:31 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
It is stamped Simplex/Nathan. I couldn't make out the size, however today I found the delivery pipe has a lot of pressure built up (more than normal/more than just a quick release of steam and water) so I tried lightly tapping the boiler check and cycling between running the injector and then opening the delivery tube drain valve, which seemed to eventually allow the check valve to start loudly seating again which I hadn't been hearing. After trying this a few times things started running and sounding just fine. Hopefully we'll see if it lasts tomorrow. Thanks for your input. If you still have any advice or if the type of injector clued you to something that I missed I'd like to know. |
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| Author: | DBH [ Tue Mar 29, 2011 8:22 pm ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
Sounds like you might need to rebuild a boiler check valve. There is a reason it is sticking. Dave Huffman |
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| Author: | Dave [ Wed Mar 30, 2011 10:42 am ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
The back pressure could also be front pressure coming through leaky steam valve in the injector and building up in the feed pipe, or if the pipe runs along an unlagged part of the wrapper sheet perhaps boiling some water inside itself. I had a problem with a lifter and a check that just wouldn't for long - added a reducing T and a little drain valve just past the injector so i could leave it cracked to vent between injection, and shut it off after priming. It also made a convenient place to plumb in a hose for cleanup. dave |
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| Author: | DBH [ Wed Mar 30, 2011 10:48 am ] |
| Post subject: | Re: Non lifting injector won't continue to hold... diagnosis |
If the check valve works after tapping I still would say it is a check valve problem. At the very least I think the check should be taken apart & checked for damage. DBH |
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