Author Topic: New Mills Pumping Station  (Read 25267 times)

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #345 on: May 18, 2022, 12:30:28 AM »
Hi MJM and Don. This seems to be a reasonable synopsis of the pump actions  and I am not able to take anything apart ..Yet... I was assuming that the outside curved parts on the end caps casting took the air up tp the top flanged part on the top of the condenser body to the large hand wheel Valve . I would have thought that the output check valves would have to be quite close to this valve to prevent the compressed air travelling towards the other end of the piston cavity !! The curved parts in the inlet holes may indicate that the piston is quite small ??..So thanks for the info and there must be lots of these pumps in use and in muse
 I have now collected some bar stock to construct the pump body but it will not be a functioning part unfortunately.

Willy

Offline Charles Lamont

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Re: New Mills Pumping Station
« Reply #346 on: May 18, 2022, 09:44:52 AM »
The outlet valves want to be close to the cylinder at each end to minimise the dead volume. This is fundamental to the design of an efficient of a compressor. On the induction stroke, the compressed air in the dead volume has to expand to below atmospheric pressure before the inlet valves can open. The smaller the dead volume in relation to the swept volume, the earlier in the stroke that happens, and the greater the volumetric efficiency. The outlet valves at the other end will stop compressed air in the manifold going back into the other end of the cylinder, so the only place the air is going is out through the big valve.

Some of the photos seem to show a quite complicated arrangement of baffles and passages around the apertures. Is it possible that the six valves include both the intakes and outlets, positioned accessibly for maintenance (removal for periodic re-lapping)? 
« Last Edit: May 18, 2022, 09:49:46 AM by Charles Lamont »

Offline ddmckee54

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Re: New Mills Pumping Station
« Reply #347 on: May 18, 2022, 09:19:34 PM »
I don't want to hi-jack Willy's thread, but this compressor has tickled my fancy for some reason.  I've done a little looking on-line for Hughes & Lancaster air compressors and haven't found much.  I have however found a number of advertisements in old engineering magazines for Hughes & Lancaster pneumatic sewage lift systems.  (Seems like these guys specialized in that?)  Can anybody point me in the right direction?

Don

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #348 on: May 18, 2022, 10:20:46 PM »
Hi Don , Don't worry about Hijacking this thread as I am really confused about what is happening ing inside this  "Box of tricks" and anything/every thing is welcome to understand what is going on here ...I like the 'dead volume'  analogy from Charles and I was thinking the same thing. ...This box has a huge volume to contain a relatively small "Dead Space'.  I too have reached the internet and have not found much myself  ?!!so please continue with more info ... So started on the parts tha will be soldered and screwed together....
Thanks

Willy
« Last Edit: May 19, 2022, 03:16:08 AM by steam guy willy »

Offline MJM460

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Re: New Mills Pumping Station
« Reply #349 on: May 19, 2022, 11:45:23 AM »
Hi Willy,

 It might help clarify the arrangement if you remember that the large block actually has four quite distinct internal spaces. 

Most obviously, the two compression spaces, one at each side of the piston.  These are the ones which need to have minimum dead volume when the piston is at the respective end, but have to be large enough to accept the whole intake volume at sub atmospheric pressure when the piston is at the other end.  They have to accomodate two valves, or sets of valves, to isolate them from the outside world without excess dead volume.

Then there is a chamber to bring the incoming air to the suction valves.  This has to be quite large to allow installation and servicing of the valves.  It generally has an opening with a cover over each valve again to assist in valve installation and servicing.  That inlet pipe from outside the building comes to this chamber.  The volume is not important as long as you can access the valves.

Finally there is the discharge chamber.  Obviously quite separate from the inlet chamber.  This chamber collects the air from the discharge valves and has the connection to the discharge pipe.  Again the volume is not important so long as you can service the valves, and it also has a cover over each valve to allow the necessary access from the outside.

Larger cylinders tend to have multiple smaller valves rather than a single large valve, and these valves require a lot of area for installation, so the inlet outlet collector chambers have to be large and this is reflected in the overall size of the block.

The basic arrangement of large reciprocating compressors has been refined a little from your example, but not significantly changed to this day.

I hope this clarifies the arrangement a little.

MJM460

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

Offline ddmckee54

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Re: New Mills Pumping Station
« Reply #350 on: May 19, 2022, 06:18:44 PM »
Willy:

I've hit a dead end.

I tried searching for "Hughes & Lancaster" + 1898 and got several hits.  The most promising was a lead to the March 21st, 1890 issue of "The Engineer" which had an article on a compressed air tram with illustrations.  My guess is that Hughes & Lancaster did the compressed air system.  That issue has been digitized and is available on PDF - to registered users.  I registered and tried to download the article, but they charge for the downloads.  I've got NO problem with that, and tried to sign up for the 3 download option.  Turns out my credit card will not allow such over-seas shenanigan's. 

I was hoping that in the article we might get a glimpse of the Hughes & Lancaster air compressors and maybe a different illustration.  Maybe somebody on your side of the pond can help out? 

But that article also might just be another dead-end.  I have NO clue why it is that I ALWAYS pick the odd-ball stuff to get interested in.

Don

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #351 on: May 20, 2022, 03:12:22 AM »
Hi MJM, thanks for this and it does clarify things greatly  yes the block is very large and is bolted firmly to the bed plate with no spaces anywhere underneath that are visible so an indication that the air intakes from the outside pipe, incidentally it is facing west towards the UK's prevailing wind ?!  As the pump is double acting I would have thought that the outlet valves would be very close to the vertical outlet pipe. these pipes are very large for some reason and all four pumps are connected to it.

Hi Don, I have used Graces Guide  quite a lot in the past when it was free but yes now you have to pay for it However it has e wealth of info in it with many worthy publications .  I may be able to find a copy of The Engineer  here in the UK ! Thankyou for your help though and we will see what transpires .

I have continued with the pump block lots of drilling and tapping to do

Willy

Offline MJM460

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Re: New Mills Pumping Station
« Reply #352 on: May 20, 2022, 12:56:46 PM »
Hi Willy, the discharge valves are of necessity near the heads of the engine so there is no extra dead volume between the cylinder head and the valves.  So the discharge chamber has to be about as long as the cylinder to collect from both ends.  The outlet pipe is usually connected to this chamber somewhere around the middle.  The distance after the valves to the discharge manifold is not very important.

A point about the discharge valves that might not be so obvious is the the discharge valves need to be at the bottom of the cylinder so that any liquid that enters the cylinder is discharged.  Quite a small volume of liquid can cause really serious damage to a reciprocating compressor if it is trapped in the cylinder.

Gravity has always been very effective at ensuring liquid water gathers at the bottom of the cylinder!

The inlet valves are then located in the only place remaining, at the top of the cylinder.

With the cylinder bolted down to the base, the discharge line might be at the side.  This complicates the shape of that discharge collector cavity.

The main issue with the inlet facing the prevailing wind is how much rain is collected by the pipe.  However usually rain can also come from other directions, so the inlet pipe needs to be arranged so that any water is always separated and drained before it reaches the compressor.

MJM460

« Last Edit: May 20, 2022, 12:59:54 PM by MJM460 »
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Offline ddmckee54

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Re: New Mills Pumping Station
« Reply #353 on: May 20, 2022, 05:53:48 PM »
MJM460

Keeping the discharge valve close to the cylinder is why I thought they were on the bottom half of the cylinder caps.  They would probably be installed from the inner side of the cap and discharge into the cavity in the bottom half of the cap.  That would eliminate any dead volume between the cylinder and the valve.  But servicing them in that location would be a royal pain.  That also assumes that there is a connection on the bottom side of the compressor to the air receiver/s.

IF that is where they are, you would have to remove the cap to service the discharge valves.  It looks like there is enough room that a clever serviceman could slide the cap away from the cylinder far enough to service the valves - still wouldn't have been any fun.  Getting that cap sealed up so it didn't leak any air wouldn't be any fun either.  I wonder if these are fairly low pressure air compressors?  To do their job of ejecting sewage, you'd need a lot of volume, but not much pressure.  They probably REALLY wanted to avoid making a poop cannon.

Then I started wondering just exactly what was under those side chest covers?  That would be a great place to put the discharge valves, they'd be relatively easy to service in that location.  BUT then you'd have all that volume between the valves and the cylinder cap that you'd have to compress, on EVERY stroke - that would cut your compressor efficiency WAY down.

Nope, I think the side covers are just there to cover the cooling jacket openings, it'd be easier to cast that way.  In one of the previous images, I believe it was IMG_0102 that shows a small-ish pipe connected to the bottom side chest on one side of the compressor.  In that same image you can see a similar sized pipe that is connected to the top of the side chest of the compressor in the background.  I'd be willing to bet dollars to donuts that those small-ish pipes are the cooling water inlets and outlets.

Don

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #354 on: May 21, 2022, 02:30:19 AM »
Hi MJM, Thanks for this and more info is making things a lot clearer, It will be good to make a sectioned drawing to find out what is actually happening ...perhaps finding some patent descriptions could be useful.  There must be some very clever porting in the castings as well !!
Hi Don , Yes I have found some useful pics that shows some pipes top and bottom that could be there to supply the cooling water There is a pressure valve on the casting that goes up to  175 psi. 5 bar  but I don't know if this is original ? There are two sets of these turbines and compressors so they could have enough downtime to make repairs and adjustments. These compressors were working g 24/7. so perhaps the efficiency was not that critical as the air was used intermittently to activate the Shone ejectors...letting the syphon system operate to move the sewerage.   
I have made the new parts ,silver soldering the separate items together.

Willy
« Last Edit: May 21, 2022, 02:41:32 AM by steam guy willy »

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #355 on: May 21, 2022, 02:51:23 AM »
A few pics of the shone ejector and the drain cock and Pressure gauge ....

"W"

Offline crueby

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Re: New Mills Pumping Station
« Reply #356 on: May 21, 2022, 02:57:54 AM »
Looked up the Shone ejector, found this video showing a cutaway view of it in action:


Offline MJM460

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Re: New Mills Pumping Station
« Reply #357 on: May 21, 2022, 12:59:22 PM »
Don, I think we are both heading the same direction.  I totally agree about the water chambers as well, confirmed the the extra pictures Willy has posted.  Makes for a very complex casting.

Chris, thanks for that video, it ads to the sketch Willy provided way back, and explains how the compressors work in the system.

MJM460





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Offline Charles Lamont

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Re: New Mills Pumping Station
« Reply #358 on: May 21, 2022, 09:34:20 PM »
I don't think we have got to the bottom of the inlet and discharge valves yet.

I think we are agreed that the curved shapes on the tops of the cylinder covers are passages communicating with the box on the top of the cylinder to the big valve, and that valve is the on the pressure side. I think we have also agreed that a sensible design would require all the valves, inlet and outlet, to be accessible for maintenance.

I don't accept that the discharge valves have to be at the bottom for clearing trapped water. It is a reasonable argument, but I don't think it is conclusive.

Now, in so far as I can see from peering into those six holes in the numerous photos, at least the top two chambers have pretty much got to lead to that curved delivery passage. Furthermore, the cylinder cover has a similar rectangular projection below, and I think it very likely that that is the air inlet to to the cylinder cover.

But this is where I get stuck. I had initially supposed that some of the six apertures would have housed the inlet valves and some outlet, but looking as closely as the photos allow, I cannot see walls that would be needed to separate inlets and outlets. On the contrary, from what can be seen, it looks to me as though all six apertures are probably connected. So if they are all for delivery valves, where are the inlets?
     
Incidentally, I would be quite happy with four inlets and two outlets, on the same principle as a three valve IC engine.

Alternatively, throwing in another spanner to flavour the pot, where are the over-pressure relief valves? Are those six holes perhaps just for safety valves, with the ins and outs somewhere else entirely? 
 

Offline steam guy willy

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Re: New Mills Pumping Station
« Reply #359 on: May 22, 2022, 02:17:33 AM »
Hi Chris, thanks for the video and it shows quite clearly how the system works ..it also led to other videos on the same theme .
Hi MJM , thanks or the reply and I would love to get back in the BLDG with a video probe and mirrors and also putting my fingers into the apertures to see how they connect ?!!
Thanks Charles , and more food for thought ...I will make some more sectional drawings to try and work out what is possible with the porting arrangements ??!!!  I may be able to locate the "ENGINEER" volume as the S.M.E.E. in London have a complete set ?? If the top curved portion goes to the top horizontal channel where the outlet hand valve is the air must also continue to the other ends curved portion to temporarily keep the outlet valves closed ...?!   so , the mystery continues  Thanks for all the comments and its good for our brain cells to stay young and active ??!!

Cheers
willy