Author Topic: New Mills Pumping Station  (Read 25272 times)

Offline MJM460

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Re: New Mills Pumping Station
« Reply #360 on: May 22, 2022, 01:03:07 PM »
Hi Charles, I am basing my comments on modern compressor design, and this will have developed a little from the historical machines Willy is modelling.  Also there minor differences in detail between manufacturers.

The attached picture (the third one) is a cut away drawing from Ariel, a compressor manufacturer in Columbus, Ohio,  and may help clarify how the valves are set up.  Certainly, Willys compressor has the valves in the heads, which are more awkward for servicing, and this makes for more options in carrying the gas to the inlet and discharge pipe nozzles, but the principle is the same.  Other manufacturers in USA and in Europe use very similar details.

The valves are actually seated at the inner compartment where the compression happens.  You can see how the arrangement causes minimal dead volume.  The valves are retained by sleeves, which in turn are held in place by the covers you can see on the outside.  The picture shows flanged covers, but these are relatively large compressors.  (The one shown is rated at about 5200 hp.)  I think the New Mills compressors have screwed in covers, by the look of some of the pictures.

On larger machines those retainer cages are quite heavy, and require a special jig to support the weight as they are withdrawn.

I can assure you that the inlet valves are at the bottom for the reason I gave, but of course, this may due to learning the lesson with historical machines built the other way.  We know now how to do it.

Unfortunately this machine does not have cylinder cooling, and that adds a further dimension to the cylinder casting complexity when it is included.  The New Mills machines do appear to have water cooled cylinders, which are not unusual.

I have lost touch with where the inlet and discharge pipes are located, perhaps Willy can set me straight there.

I hope this picture, and the diagram, even though a modern machine, help with understanding of of the parts of the older machines.

MJM460


The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #361 on: May 23, 2022, 02:27:20 AM »
Hi MJM, Thanks for this info and I am posting the photos again that have been photoshopped to give a clearer image of the internals. Do you have the text with the cut away drawing that indicates what the numbers refer to ?? I will do some drawings soon that are sectioned with what I can see from the pictures  ! 2 of the pictures show the head with the piston up against it and the other one is at the other end with no sight of the piston , The final pic shows the piston with some damage to it ??

Willy
« Last Edit: May 23, 2022, 02:30:32 AM by steam guy willy »

Offline MJM460

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Re: New Mills Pumping Station
« Reply #362 on: May 23, 2022, 01:08:40 PM »
Hi Willy, unfortunately I have not been able to find original prints of these diagrams, though I should have brochures packed away somewhere.  I have even been to the factory to witness a test run. Always a very informative experience.  I guess not being able to find them proves my wifeís point that I should throw them out!  So those diagrams are just pictures available on the web.  Obviously not supposed to find them useful, as they do not come up readable, nor do they link to readable pages.  Looks like a great search result until you actually need to read the drawings.  I did manage to read the words at the bottom, and they indicate that the diagram is supposed to be a suction valve on one side of the centreline, and a discharge valve on the other side of the centreline.  It is clear that superficially, they are quite similar.

I labelled the key parts with highlighter pens on one diagram, and on the cutaway.  They are legible on my copy and check with my labels.

Modern valves have two layers as shown, with plates and damper elements inside that open and close as required.  The discharge and suction valves look similar in this view, it is the arrangement of the internals that determine which is which.  Now days there are special provisions to ensure you canít get them the wrong way around.  Again the result of learning what doesnít work the hard way.

The retainer cage actually holds the valve in place.  The openings in the side of the cage allow the gas to flow in or out from the valve.  I donít know whether your machine has those or not, it is possible that the valves are simply screwed in place from the outside with a special tool, then the cap screwed in to seal the outer shell.  Definitely looks like a threaded hole on the outer surface.  The outer covers on the picture I showed are flanged which is now normal on larger machines.

I hope these pictures and explanations help you understand what you are looking at on your machine, even though they are not necessarily exactly the same.  The principle is definitely the same.

MJM460





The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #363 on: May 24, 2022, 01:21:45 AM »
Hi  MJM ,  Thanks for this and I will try and arrange another visit...I have found some more info on the web about the history of the site and also a fairly recent new use using an Archemedies screw to generate electricity ...also a pic of another pump bu Hughes and Lancaster. so thanks for the latest info ..
Willy

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #364 on: May 26, 2022, 02:55:02 AM »
So,... thanks for all the input about this air pumping machinery and now to making it ..the side covers top part and an end cover have been started on and lots more to scheme out ...
Willy

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #365 on: May 28, 2022, 02:00:14 AM »
A bit more work on the engine ...the end caps are made and now the curved bolting flanges need to be made,,,also the large holes need to be accurately drilled and tapped ...

Willy

Online crueby

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Re: New Mills Pumping Station
« Reply #366 on: May 28, 2022, 04:41:05 AM »
Coming together nicely!   :popcorn: :popcorn:

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #367 on: May 28, 2022, 12:25:32 PM »
Hi Yes but very slowly   Thinking about the transfer air valves ????? do they work sideways  ??????

Willy

Offline MJM460

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Re: New Mills Pumping Station
« Reply #368 on: May 28, 2022, 12:48:27 PM »
Hi Willy, it basically depends on the construction detail.  The important point is that the construction detail should not allow the valve plate to fall out of position at that neutral point where the air flow is close to zero, so no longer holding the valve fully open or closed.  They will likely need a light spring to make sure they close without too much reverse flow.  Have you got a sketch of the valve construction, at least the construction detail you are planning to use?

Plate valves in a modern machine have a large number of small springs to ensure that each segment of the plate is pressed back against the seat as soon as the intended flow reduces to the point where the flow no longer holds it open.  Only light springs are used so the cylinder pressure does not have to be too much above the discharge line pressure to open them.

MJM460



The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #369 on: May 29, 2022, 01:49:45 AM »
Hi MJM , Thanks for the reply  and the reason I asked is that I think that as the round openings are half way closed off in the castings it looks like the closed off portion has openings that may go up to the top of the main casting via the curved outside part of the piston cover to go to the shared main hand valve . the two photos show both ends of the cylinder covers one with thepistonallmost fully closed and the other end open to the cylinder. I have made a drawing to show how the 6 openings may connect with the cast in porting passages,,?? the valves in these 6 openings would have to be sideways on to operate ,  and that is where my comment came from. Also in your picture of the engine there is a spring on the piston rod  ? there is also a spring on this engine ??. So , there must also be a spring valve on the air input side and this may been on the lower part of the cylinder cap ??
so the construction continues ...

Willy

Offline MJM460

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Re: New Mills Pumping Station
« Reply #370 on: May 29, 2022, 01:06:56 PM »
Hi Willy,

I think you have the air flow correct for the discharge valves in your sketch.  Just turn the sketch upside down, for the inlet flow, but you have just not shown the actual valves.

I think you will find that the valves sit on that machined seat, not on the half ďclosureĒ which is a bit further in and allows flow to the entire valve face, with minimal extra dead volume.

I suspect the valves extend outside the cylinder surface because there is not enough room inside the cylinder diameter for adequate size valves.

The assembled valves are a bit like a disk with internal air passages.  Made in two layers, with a moving plate in between that is pushed off the seat by air flow, then reseated by a spring or springs when the flow would otherwise reverse.  They have been removed at some stage, perhaps to stop them rusting up while the machine was not in use.  Specific shapes have evolved since you machine was built, but the basic principle is no different to a leather flap over a hole in fireside bellows.  Just the leather flap would not withstand continuous 24/7 operation for three years as modern process compressor valves are expected to achieve (and do).

Based on my knowledge of modern machines, I suggest the valves are held down on that circular seat by a hollow cage which allows the airflow out into the collector chamber per your sketch.  The cage in turn is pressed down by a screwed cap which fits the threads you can see in your pictures.  A special tool to hold the lot together while the valve is inserted, as I mentioned before.

I wonder if your museum has a box of small parts for those compressors hidden away somewhere.  Hopefully with a full set of valves and some spares, or at least enough to allow some replacements to be machined up.  Hmmm, perhaps not such a small box!

The drawing I posted earlier does not have a spring on the shaft, those features are separate grooves in the seal casing, used for leakage collection and buffer gas injection, not a spiral, though I can understand the confusion at a quick glance.  Sometimes called chambers, though the form is more like a large groove which encircles the shaft.  The sealing element is divided into sections, separated by a lantern ring at each of those grooves to allow gas collection or injection.  External piping is fitted to pipe the gas in or out.  I can explain more of that if anyone is interested, but the arrangement is not required for an air compressor where some leakage is not so much of a problem.  But the drawing is for a process compressor for flammable or toxic gases, where leakage to the atmosphere is not acceptable, hence the more sophisticated seal.  The drawing also mentions water cooling but I donít think the detail of that is on the drawing.

I really donít a know what the spring around your piston rod gland is for, that one is still puzzling me.

MJM460


The more I learn, the more I find that I still have to learn!

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #371 on: May 31, 2022, 02:15:36 AM »
Hi MJM , Yes I see what you mean about the valves and I think the inlet valves are under the side plates ...there are only 12 nuts to undo so would be quite quick for any repairs. The building is not actually a museum as such and it remains as left when it last worked in the 50's...there was some preliminary work with a viewing platform back in the 80's but nothing more has happened since. I have looked and have not seen those valves anywhere. Yes the spring is a mystery could it be an automatic water relief valve ??
I have done some more work on the cylinder caps drilling the holes and tapping them  etc

Willy

Offline ddmckee54

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Re: New Mills Pumping Station
« Reply #372 on: May 31, 2022, 05:21:02 PM »
Willy:

My first thought when I saw the spring was that it was to keep pressure on the packing gland for the shaft seal?  But it would be pushing the wrong direction for that.

There are 6 valves in the top half of the cylinder cap, we can look through the openings where they would be installed.  We are assuming that there will probably be more valves on the bottom half that handle the flow in the opposite direction.  When you look in through the opening where the valve cage would be installed you see a circular line running through the opening.  You are assuming that the raised portion is the cylinder and the depressed portion is the piston.

Here's a "what-if" for you.  What if what we are seeing IS the piston? And what if the piston extends beyond the opening, AND it has a depression carved into it?  That depression could serve 2 purposes.  First, it would give you a place for the locking nut that will hold the piston onto the shaft.  And that depression just MIGHT be clearance for the valves that we are pretty sure are installed in the bottom half of the cylinder cap - the valves that handle the flow in the opposite direction.  I think we've been assuming that the valves on the bottom would be a mirror image of the valves on the top, but what if they aren't?  If the piston extends beyond the opening, that would give you full flow across the entire face of the upper valves.

Do you have any clue why the entire cylinder cap appears to be covered in grease?  That's always bothered me why they did that.

Don



Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #373 on: June 02, 2022, 01:03:45 AM »
Hi Don thanks for this insight and what we need to do is to get in there with some spanners !!!  The rear of the pumps are not actually connected to anything so that would be a good place to start. I don't know why the grease is there ..perhaps it is to protect the surfaces from rust because>>>>>>>>??

It is Strumpshaw steam engine Rally for the next 4 days so I will be there having fun  :whoohoo: :cartwheel: :)

Willy

Online crueby

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Re: New Mills Pumping Station
« Reply #374 on: June 02, 2022, 01:19:35 AM »
Have fun at the rally - and take pictures!!!