Talk:Injector

A Link To The Past
The ' eductor-jet pump' link just sends you back to this page. What the cabbage? — Preceding unsigned comment added by 69.171.96.6 (talk) 15:12, 28 January 2013 (UTC)

Move
Moved to article. --Dore chakravarty 05:04, 5 December 2005 (UTC)

atmosphere link?
In the second paragraph the word "atmosphere" links to a disambiguation page, what does it mean in this context? Bergsten 21:28, 6 December 2005 (UTC)


 * The said word refers to Earth's atmosphere please. --Dore chakravarty 22:37, 6 December 2005 (UTC)


 * Thanks! Bergsten 22:38, 6 December 2005 (UTC)

Suggested merger
I suggest that Injector and Steam injector be merged. Biscuittin (talk) 09:45, 9 December 2007 (UTC)


 * I just finished merging Steam ejector into this Injector article. I agree with you that Steam injector should also be merged into this article. I will try to do it sometime in the near future. Regards, - mbeychok (talk) 21:16, 5 January 2008 (UTC)


 * Why? Firstly, you have done this without prior notice or discussion, which I believe is normal with merges. Secondly, In doing so you have disposed of useful information such as the use of ejectors in providing the vacuum for steam locomotive braking systems. It may not interest you, but someone else probably had a good reason for writing it. If you are going to do a merge, please don't throw away perfectly good content.
 * I do not disagree with the idea of merging these three articles, I just want to be sure that the result will be an improvement. Also, I have been vaguely intending to put more detail in Steam injector, such that it might be enough to justify splitting it back out. Bill F (talk) 02:11, 11 January 2008 (UTC)


 * As suggested by User:Biscuittin above, a proposed merger tag was placed on the Steam injector article and it was merged into this article about a half-hour ago.


 * I sincerely regret that you are disturbed by having both the Steam ejector and the Steam injector article merged into this article. All three articles covered pretty much the same content. I assure you that I spent about 8-10 hours on each of the two mergers in order to make sure, to the best of my ability, that no content was summarily left out of the merges.


 * Please read this Injector article thoroughly and carefully and I think you will be pleased with how I handled the merges. If you are not pleased, then feel free to make whatever edits you feel to be needed. Regards, - mbeychok (talk) 02:41, 11 January 2008 (UTC)

I'm of the view we should try and separate injector and ejector. The two contrivances carry out two totally different jobs. The only link between the two is utilisation of the Bernoulli effect. 7severn7 (talk) 21:59, 24 January 2010 (UTC)


 * I agree. Globbet (talk) 23:30, 25 January 2010 (UTC)


 * I apologise for being quite late to respond to 7severn7 and to Globbet. First, let me say that this article is not about "contrivances" ... there is nothing contrived about the "device" described in this article.


 * As someone once said "a rose is a rose by any other name". The device described in this article has many names (injector, ejector, steam injector, eductor, jet pump, thermocompressor, aspirator and perhaps others as well) ... but they are essentially all one and the same device. The device is used for many different purposes as explained in the section on modern uses. We do not need separate, standalone articles for each of the uses or for each of the various names of the device. mbeychok (talk) 20:48, 26 February 2012 (UTC)


 * Of course they're not the same device. Injectors and ejectors might use the same principle, but they have one incontrovertible difference: the outlet pressure of an injector must be greater than its supply pressure. This leads to their additional internal complexity. Andy Dingley (talk) 21:00, 26 February 2012 (UTC)


 * "Of course they are not the same"?? Even though they "use the same principle" as you admit?? Let us take some examples:
 * There are centrifugal compressors, reciprocating (positive displacement) compressors, scroll compressors, rotary screw compressors, etc., etc. ... they vary in design and in complexity, but they are all compressors.
 * There are shell and tube heat exchangers (variants:parallel flow, cross flow, counter-current flow), plate heat exchangers, kettle-type reboilers, surface condensers, etc., etc. ... they also vary in design and in complexity but they are all heat exchangers.
 * There are centrifugal pumps, positive displacement pumps, gear pumps, lobe pumps, etc., etc., ... they also vary in design and complexity but they are all pumps.
 * There are various makes of automobiles such as Ford, Toyota, Mercedes, Rolls-Royce, Honda, Volkswagen, etc. Then there are autos fueled by gasoline, or fueled by diesel oil, or run by electricity, or hybrids (gasoline and electricity). But they are all automobiles despite many differences in design and complexity of design.
 * I spent over 60 years as a chemical engineer designing oil refineries, petrochemical plants and power plants, all of which involve injectors for many different uses. But I guess that means nothing to someone in the class of 2007, right??


 * Please don't start discussions with an attitude of "Of course, you are wrong". You might try "I disagree" or "I think you are incorrect". In other words, don't be so cocksure of yourself. mbeychok (talk) 21:54, 26 February 2012 (UTC)


 * What do heat exchangers have to do with this? Nor for that matter, your 60 years as a chemical engineer - that's a sheer irrelevance. We work here by sourcing from external sources, and by consensus. It looks like three people here think that injectors and ejectors are sufficiently different to warrant separate articles. So did the patent office, granting Giffard a patent for his new injector even though the ejector was already a well-known device. A patent that was so controversial at the time, as its claim to generate a higher output pressure than input was seen as tantamount to a perpetual motion machine!
 * I am uninterested in your personal qualifications and pointlessly verbose comparisons with compressors and car engines. Do you actually have any references that injectors and ejectors are indistinguishable? Or that anything described as an ejector can act as a Giffard injector does? Andy Dingley (talk) 23:18, 26 February 2012 (UTC)
 * They seem to work by exactly the same principles, they even share the same diagram in the Wiki; this is not a distinct topic.GliderMaven (talk) 00:05, 27 February 2012 (UTC)
 * Only superficially. An injector condenses the driving steam, using its latent heat as well as kinetic energy. It also requires an overflow, without which it cannot start, and, for efficiency, a one-way valve to prevent air ingress through the overflow once operating conditions are established. Other devices generally do not involve a change of phase in the operating fluids. Globbet (talk) 00:36, 27 February 2012 (UTC)
 * I do not think it's in the interests of the users to split it in this way. They are still, very substantially, the same device, they work in the same kind of way, and they do the same kind of thing.GliderMaven (talk) 02:34, 27 February 2012 (UTC)
 * It's a bit like turning a vacuum cleaner from suck to blow and claiming it's a different device.GliderMaven (talk) 00:05, 27 February 2012 (UTC)
 * "they even share the same diagram in the Wiki; this is not a distinct topic."
 * Please come back with a real reference, not just quoting a filename.
 * The underlying problem here seems to be our octogenarian expert's assumption that the chemical industry was all that ever used injectors. Yes, if you're working at low pressure and have a supply of high pressure process steam available, then an ejector and an injector have little difference other than their detail proportions.
 * Now consider it again for the problem of boiler feedwater. How does an injector working at boiler pressure increase the pressure of its delivery such that it's greater than the supply pressure? This can't be done with the simple ejector that you describe, hence Giffard's invention of the more complex boiler feedwater injector. That is not the same simple device. Andy Dingley (talk) 00:40, 27 February 2012 (UTC)
 * According to the definition given at the beginning of this article, they are the same device. And that's all the matters for this article.GliderMaven (talk) 02:34, 27 February 2012 (UTC)
 * If there's not enough room in this article to cover it fully (which as it happens doesn't actually seem to be the case) then you could subarticle the steam injector off this one, so that you do not completely remove it from this one.GliderMaven (talk) 02:34, 27 February 2012 (UTC)


 * "According to the definition given at the beginning of this article, they are the same device. And that's all the matters for this article"
 * Been here long? You claim that the article is referenced from itself? Andy Dingley (talk) 03:01, 27 February 2012 (UTC)


 * No, the article and all articles in Wikipedia are scoped by themselves. At the top of every article is a description of what that article covers. Go read the scope of the article. Unless you're going to rewrite that description, the steam injector is covered by THIS article. Good luck with that, having read it, that looks reasonably hard, but may be possible.GliderMaven (talk) 04:56, 27 February 2012 (UTC)


 * From his comments made here, it appears that Andy has not taken the time to read the entire introductory section. mbeychok (talk) 06:34, 27 February 2012 (UTC)


 * I not only read it, I started re-writing it to make it clearer for a de-merged scope between injectors and ejectors. You reverted this immediately, without discussion. Andy Dingley (talk) 10:56, 27 February 2012 (UTC)

(unindent)Andy, did you not note that I carefully said (above) that "...they are essentially all one and the same device"? I did not say they were identical. Have you forgotten that you admitted they "... might use the same principle" ?? Are you deliberately being obtuse when you say that you don't understand the corollary with heat exchangers, compressors, pumps and autos? Each of those words encompasses various types of the same basic principle ... heat exchange, compression of a gas, pumping of a liquid and automotive power. Wikipedia has one article covering all types of heat exchange, one article covering all types of compressors, one article covering all types of pumps ... even though the various singular types within each category may serve different uses and are not identical with each other. So why are you so fixated on the point that they are not identical in every aspect?

By the way, all injectors do not use steam ... there are many other fluids used as their motive fluid. The same holds true for ejectors, eductors, aspirators, etc., etc.

It is your type of attitude that eventually drives people away from Wikipedia. mbeychok (talk) 01:26, 27 February 2012 (UTC)


 * How many articles do we have on compressors? On heat exchangers? Are you seriously suggesting that we merge petrol engine and diesel engine into automobile engine?
 * As to attitude, then yours is evidently that anyone who doesn't have 60 years experience (and a thorough disregard for external references) should be excluded. The only other person who agrees with your viewpoint also thinks that the difference between an ejector and an injector is as simple as "like turning a vacuum cleaner from suck to blow ". Andy Dingley (talk) 01:41, 27 February 2012 (UTC)
 * Cut out the ad-hominen attacks, right here, right now, or you're going to be appearing on the relevant civility page.GliderMaven (talk) 02:34, 27 February 2012 (UTC)


 * Andy, WP has one article entitled Gas compressor ... with links to any other sub-articles on specific types of compressors. The same is true of Heat exchanger and Pump. If you feel that some specific type of injector/ejector/eductor/jet-pump/thermocompressor/aspirator/etc. needs a separate sub-article, then go ahead and write it and link to it from this article as suggested by GliderMaven ... but please don't mention that "... of course, it is not the same as ...". mbeychok (talk) 04:30, 27 February 2012 (UTC)


 * There's no problem with an overall article for gas compressor and sub articles for the many sub-types. That's a good structure for complicated topics. The problem here is that you're trying to make gas compressor (or its analogue, injector) the only article, and repeatedly merging in any separate articles, even while others are in the middle of re-writing them. That's just edit-warring.
 * If you go that route, then I would be happy with an overall article at injector, one on the primarily suction producing devices at ejector and (most importantly to separate) another article for the physically distinct Giffard device at feedwater injector.
 * As the article stands, it describes the overall situation as if there is one, and only one device, and it opens with the sentence, "An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermocompressor is a pump-like device". This is a nonsense, and is confusing to readers who arrive hoping to find what the difference is between injectors and ejectors, only to be told that there isn't onee.
 * I admit, my interest here is more about steam locomotives than chemical engineering. I don't know the abundance of Giffard injectors in chemical engineering, but AIUI, they're not used - it's easier to simply use a higher supply pressure than the delivery needs (and thus a simple two cone ejector), because such a pressure is commonly available. For the steam locomotive situation though, locomotives are frequently fitted with both injectors and an ejector, devices that are quite different and used for entirely different purposes. This merged article fails readers who are seeking the difference beetween the two. Andy Dingley (talk) 10:53, 27 February 2012 (UTC)

Andy has neatly identified the difference with his example from locomotives: there are two completely separate functions with very different methods of operation. The topic is sufficiently distinct from general engineering to warrant specialised articles. The merger was totally misconceived and should be reverted.--Old Moonraker (talk) 12:25, 27 February 2012 (UTC)
 * Andy, when did I "repeatedly merge in any separate articles, even while others are in the middle of re-writing them." ??? If you will look above, the original merger was done once on January 5, 2008 after it was first suggested by Biscuittin. That was 4+ years ago. I subsequently left WP for about 4 years and have only very recently come back to see if it had changed. Sadly it has not. Why are you fabricating lies about me? Is that how you hope to get your way?


 * As for your statement "This is a nonsense, and is confusing to readers who arrive hoping to find what the difference is between injectors and ejectors ...", I doubt that. After all, that doesn't seem to have happened during the last 4+ years. Probably because of the lack of interest in steam locomotives by most people other than hobbyists. mbeychok (talk) 16:29, 27 February 2012 (UTC)


 * That'll be here, "Deleted the very major revisions unilaterally made by Andy Dingley without any prior discussion on the Talk page and without reaching a concensus about unilaterally doing so." after three people on the talk page had disagreed with your merge. Andy Dingley (talk) 16:44, 27 February 2012 (UTC)


 * As stated above, the merger was first suggested by Biscuittin and I did not act unilaterally. You accused me of "repeatedly" reverting. That is not true. You accused me of doing so while "others" were re-writing the article. That is also not true. I reverted you singularly (not plural "others") and I did it once, not repeatedly. I did so for the reason stated ... that you unilaterally tore the article apart and deleted major portions of it without prior notification and before we began this discussion here on the Talk page. So I repeat my question, why are you fabricating lies about me?


 * Once more, all forms of the device variously called injector, ejector, eductor, eductor-jet pump, thermocompressor, aspirator, etc. utilize a convergent-divergent nozzle and all of those forms can and do use various fluids (either gas or liquid) to provide the motive energy required to accomplish their various usages. One need only to look at an injector and at an ejector to see that they both use essentially the same principle and essentially the same convergent-divergent types of nozzles. They all use the Venturi effect which is a particular case of Bernoulli's principle. I stand by my statement that injectors, ejectors, eductors, eductor-jet pumps, thermocompressors, and aspirators are essentially the same device. Any knowledgeable engineer or physicist would undoubtedly agree with that statement. This is my last word on this subject. I have better things to do with my time and I resent being the target of your lies about my behavior. mbeychok (talk) 18:23, 27 February 2012 (UTC)

More info for downstream equipment
Do you think this article would benefit from more stuff on downstream equipment from these ejectors? Not sure if this to much information for an article such as this. These systems are notoriously difficult to operate and design. However, these issues probably do not apply in all areas of ejector appplication. Toothtools (talk) 21:38, 27 June 2008 (UTC)

Steam injector
Such "steam injectors" take advantage of the latent heat released by the resulting condensation of the motive steam.

In which way does the steam injector take advantage of the latent heat? The latent heat will pre-heat the water before injection, but the same principle should also work with a fluid that has no latent heat. What is needed is a change in density by condensation. --Hokanomono ✉ 08:24, 11 June 2014 (UTC)

copied from User talk:Andy Dingley:
 * This isn't to do with injectors in general, but specifically for the Giffard boiler feedwater injector. This manages the "impossible" trick of injecting water under pressure by using a lower supply pressure than that in the boiler (or at least, one that is no higher). The extra energy needed to achieve this comes from condensing some of the steam supplied to drive the injector, releasing its latent heat. Incidentally it's well-known that locomotive injectors stop working with hot feedwater - the reason (far less commonly known) is that they're now too hot to condense some of the supply steam and thus release the energy needed.
 * Unfortunately WP has lost the previous article on boiler feedwater injectors, as one editor took it upon themselves to rewrite injector from the narrow POV of the chemical industry, and the assumption that a supply pressure can always be available which is higher than the delivery pressure needed. The current article is now unreadable, inaccurate and unsourced crap, guarded by a dedicated edit warrior.
 * If you're after a technical discussion of feedwater injectors, I'd suggest Semmens & Goldfinch's How Steam Locomotives Really Work as one of the most recent and probably most accurate explanations. Andy Dingley (talk) 15:02, 17 June 2014 (UTC)
 * Evidently WP's a good platform for publicising their self-published book though: Articles for deletion/Fundamentals of Stack Gas Dispersion Andy Dingley (talk) 15:07, 17 June 2014 (UTC)
 * Your second change is quite wrong too. The purpose of this excess energy (and why it's needed at all) is to increase the pressure of the injector delivery, such that it exceeds the boiler pressure. It has nothing to do with preheating the feedwater. Andy Dingley (talk) 15:39, 17 June 2014 (UTC)

end of copied section

I understand that condensation is nescessary. Work is pressure × volume, therefore steam (large volume) can easily pump in water (small volume). Of course you need to invest the latent heat in the boiler in order to get steam and drive the rankine cycle, but I think it is misleading to say that the latent heat released would be the source of the excess energy. The energy balance would be fine in an open cycle, too. At atmospheric pressure the change of volume is responsible for only 8% of the latent heat of vaporization. --Hokanomono ✉ 20:51, 19 June 2014 (UTC)

Nathan 4000 Non-lifting injector
The photo of the Nathan 4000 Non-lifting injector at the top of this article is pretty useless. It's unclear what part of the photo is actually an injector. Has anybody got a better one? --Roly (talk) 19:01, 28 November 2014 (UTC)

On the assumption that there's nothing particularly special about the Nathan 4000; how about this generic Steam Injector photo? --Roly (talk) 19:13, 28 November 2014 (UTC)


 * In the absence of any comment, I have replaced the image as suggested. --Roly (talk) 17:43, 1 April 2015 (UTC)

better Introduction
Before immediately just jumping into how they work, it would be good to explain the point of the device. *Why* are they used? e.g. instead of other types of pump? What is the result that's being sought?

The description says "...creates a low pressure zone that draws in and entrains a suction fluid. After passing through the throat of the injector, the mixed fluid expands and the velocity is reduced which results in recompressing..."

Which sort of hints that the purpose of the device is also for "mixing" fluids, but it sounds like it went through low pressure, and then "recompressed"... why "do and undo"? what is the end result? What has changed? Is the mixed fluid then also diffused (with some of the remaining added kinetic energy, perhaps to keep it mixed with even more air to not recondense?) Please explain.

There is too much "what's going on" and not enough "what's the point" in the introduction.

Is it "just a pump", or is it something more? (There's not much about "Injectors" in the general article on "pump"s.)

(The "Modern uses" section is just a list, but it doesn't explain how this device manages to satisfy these particular needs any differently/better than some other choice of pump... it just somehow does.)

When should one consider using an injector in a design for something that needs a pump? 104.5.72.176 (talk) 16:09, 26 July 2015 (UTC)


 * It would be better to delete this whole article and start again, although that's unlikely to happen. Mbeychok made some very bad and strongly opposed changes to these articles that have ruined them, but then had his friendly admin (who didn't understand a word of either) threaten blocks on anyone who reverted them. As a result, "injector" is now seen as a minor variant of the chemical plant ejector and Giffard's injector is no longer covered. Andy Dingley (talk) 16:58, 26 July 2015 (UTC)


 * I think we might revisit the issue now and see what editors who now watch the talk page think. Without re-engaging with the contentious issue of page merges, we could rewrite this page - as the IP notes, the lead is hopeless (in particular, you could be forgiven for thinking the injectors on steam locomotives just get water up to the clack valve and something else shoves it through) - starting with the Giffard injector and the significant fact that you can get water into a boiler using steam at lower pressure than the boiler itself. I would be strongly in favour of such a rewrite. Pinkbeast (talk) 15:59, 28 July 2015 (UTC)
 * I think this should be re-split. Injector, Ejector, Feedwater injector or Boiler feedwater injector (it's not just steam locos) and even Ejector (vacuum brake) for steam loco brakes. Andy Dingley (talk) 16:14, 28 July 2015 (UTC)


 * There's an argument for that too, but it wouldn't hurt to rewrite it - the words would still be useful after the split and the split would be more contentious. Pinkbeast (talk) 16:39, 28 July 2015 (UTC)


 * This doesn't seem to have gone anywhere. If I get the time I'll chase up my copy of OUP "How steam locomotives really work" and rewrite the unsplit page. I would not argue with a split, I'm just too lazy to do it. Pinkbeast (talk) 19:04, 13 August 2015 (UTC)

Recent reverts
Recent edits removed:

"The addition of heat to the flow of water lessens the effect of the injected water in cooling the water in the boiler compared to the case of cold water injected via a mechanical feed pump."

describing this as redundant, and the following comparison to a feed pump was dismissed with "no need to compare to a pump". I do not feel it is remotely redundant; feed pumps were (as is discussed in the article) widely used on locomotives before the invention of the injector and the injector's superiority to them (thermal efficiency, limited number of moving parts, and ease of adjustment of the water input) is entirely germane to this article. I invite comments from other editors. Pinkbeast (talk) 23:16, 31 October 2016 (UTC)
 * Comparison with feed pump certainly needed from a loco point of view, but I would have my doubts about restoring the sentence removed, which surely only applies when using exhaust steam (I'm only an ex-chemical engineer and therefore too much thinking makes my brain hurt, but if the injector is not running on exhaust steam where has the heat added to the feed water come from, other than from the water in the boiler?). From a chemical engineering point of view, a comparison between ejectors and pumps should be of interest, but would read significantly differently ('no moving parts' means you can use any number of corrosion-resistant materials you would struggle to make a reliable pump from). Generally I think the page does need to separate out the railways stuff from the chemical engineering stuff; the points to be made about one application are different from the points to be made about the other.Rjccumbria (talk) 00:32, 6 November 2016 (UTC)
 * You're quite right if the injector is run on steam direct from the boiler (a "live steam" injector), but of course that is avoided where possible. Two injectors are normally provided (and two mechanisms of some sort for refilling the boiler _must_ be provided) and at least one will normally run on exhaust steam. Since ordinarily water consumption and making exhaust steam go hand in hand, it's usually possible to refill the boiler using an exhaust steam injector. Pinkbeast (talk) 01:44, 7 November 2016 (UTC)
 * Ok, I follow; but the proviso about using exhaust steam could do with being explicit. And the more I look at the article the more I feel it needs taking in hand. As I think a previous WP-ian has pointed out on the talk page, an injector requires the motive fluid to be a condensible vapour; hence the last sentence of the 'Operation' section is spot-on for ejectors (and captures one of their principal advantages) but utter tish (and, indeed, tosh) for injectors. Rjccumbria (talk) 19:25, 7 November 2016 (UTC)

Desired improvement: the general injector and the theory of it
It would be very could if this article had more information on the theory of injectors and (easily applicable) formulas for dimensioning (theoretical formulas, and practical "cookbook" formulas taking various non-ideal inefficiencies into account). It may be good to divide this into four different regimes (in fact the articles should be generalized linking to or treating the steam injector a special case), gas-gas, gas-liquid, liquid-gas and liquid-liquid injectors (steam being gas of course).150.227.15.253 (talk) 11:19, 28 January 2019 (UTC)

Hard to understand
I found this article hard to understand and confusing. Now I know why. The article was the result of a merger that was never cleaned up. Without explaining how a simple jet pump works, the article starts with something much more complicated, and the simple version only comes later. The water injector for a steam engine is a very specialized jet pump, and the article should tell how it builds upon a simple jet pump. Comfr (talk) 18:50, 25 October 2020 (UTC)

"Eductor-jet pump" listed at Redirects for discussion
A discussion is taking place to address the redirect Eductor-jet pump. The discussion will occur at Redirects for discussion/Log/2021 March 31 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Cnilep (talk) 06:44, 31 March 2021 (UTC)