Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Tore, do you have any drawings/pictures of the exhaust outlet control valves? I know that this area is very complex and I would love to add some of this detail.

Simon
Do you mean the main exhaustvalves with grinders etc?
Tore

[NZSnowman]

Yes, any pictures or drawing of the outside.

[tore]

Simon
Main exhaustvalve system.
I am afraid I don`t have much pictures, but I guess we have to work us through the system from the main engine outlet to the silencer. In that case it might be better to comment on what you got based on your present drawings and possible photos and then to find out the details as we have done before. In the meantime I keep looking for details on my end.
Tore

[NZSnowman]

I only have two photo's from this area of the boat, very very rare to find photo's of this part of the boat. Maybe Maciek has a few pictures?

These are from U-250





http://www.town.ural.ru/ship/ship/tc14.php3

[tore]

Simon.
Main exhaust system.
You are right  there are not much pictures or drawings to find on the  subject. The system consist of an inboard exhaustvalve in a watercooled housing going through the pressurehull. The valvedisc has a wormdrive connection for rotating the valvedisc ( grinding ) which is operated from the engineroom by hand, and a wheel for shutting the valve. You can find a picture on the U historia webside. On one side you see a square shaftend protruding out of the housing , that is the connection for handturning of the wormdrive. After the inboard valve the watercooled pipe makes a bend towards aft having a branch off pipe going forward to the ballast tank blowing panel in the controlroom and to the snortmast, I`m sure you know all about that, valves and pipejoining etc. There is an outer main exhaust valve  pretty much the same as the inboard valve but the rotation ( grinding) of the valvedisc is done by pneumatic motor having the worm drive spindle through the pressure hull. The valve is shut by a handwheel in the engineroom up under the pressure hull. On the bad photo and drawing below I have tried to indicate the components. The outer exhaustvalve is used for adjusting  the exhaust pressure in the ballast tank during exhaustblowing. After the outer valve the pipe turns into a silencer which from outside look like a watercooled barrel and the flanged to a smaller barrel which is a spark arrestor before going through the casing side.
Tore

[tore]

Simon.
Outer exhaustpipe.
I guess I should add that on the U historia picture you`ll see 3-4 drainpipes which drain the exhaustpipe both from the space between the outer and inner exhaustvalve as well as after the inner valve. These drains were frequently used and ended up in a funnel box at the lower aft engineroom bulkhead, in fact I believe together with the coolingwater drainage from the outlets of the engines as we discussed previously. On the picture you will see a bigger pipe connected, I believe this is the direct engine coolingwater pipe connection. See coolingwater sketch.
Tore

[NZSnowman]

Tore, when I was reading your post and see the words "The system consist of an inboard exhaustvalve in a watercooled housing going through the pressurehull." I just remember I have a few more pictures 

These are of U-534 a Type IX.

[NZSnowman]

Simon.
That may be.  I think I have seen a drawing of the compensating box in the bottom of the saddletank. See below,  I made a rough pencil sketch indicating where to look for it you have more materials to look into than me.
Tore

This could be that pipe on the U-534

[NZSnowman]

Simon
Fuel compensating saddle ballasttanks
The valve b is a valve only in use when you select the mode you want to use the saddletanks,as fuel tanks or ballasttanks. It is a double seated valve with only two positions  either in direct contact with the head tank in the conningtower when the saddletank is used as fueltank or in direct contact with the sea when the saddletank is used as ballasttank. I believe it is controlled from outside the pressurehull under the casingdeck as it is not often used. I think it is a hatch in the deck for access.
Tore

Thanks Tore.

I have checked all my photo's and checked dive videos and found no evidence of these pipes. So this morning I started checking deck hatches and I think I can location the positions they enter the saddle tanks using the hatches. I will use this as my glide for the drawing.

Do you think the open end to the sea would have a pipe screen over the end to stop sea weeds etc entering the system?

I think I may have an explanation why I can not found any evidence of these pipes. I previous imagine those pipes would run just above the pressure hull, but now I believe there is not enough room, so the Germans run those pipes just under the wooden deck. As both the decking of U-352 and U-1021 are gone, this is why I can not found these pipes in the dive videos.

I had forgotten I had these photo's. Here are the small pipes running just under the decking

[tore]

Tore, when I was reading your post and see the words "The system consist of an inboard exhaustvalve in a watercooled housing going through the pressurehull." I just remember I have a few more pictures 

These are of U-534 a Type IX.

Well Simon I guess that`s it. I presume the VIIC and IX were pretty much alike on this detail. The cooling pipebends follow the same pattern as previously discussed, bypassing the flanges and other coolinwater jacket obstructions. Apart from these pipes every detail is hidden inside the pipe and housing.
Tore 

[tore]

Simon.
That may be.  I think I have seen a drawing of the compensating box in the bottom of the saddletank. See below,  I made a rough pencil sketch indicating where to look for it you have more materials to look into than me.
Tore

This could be that pipe on the U-534

Simon. Interesting detail, it certainly could be the box, I only miss the pipe out of the box. The idea was to have a buffer preventing contamination into the compensating system. Howewer the most important pipe for that was the fueloil venting pipe  which ended some 10 cm from the bottom of the ballast/fueltank. When fuelling, the ventcock was open and a guy watched the water coming out and stopped the fuelling when he discovered fuel coming out, but as the pipe ended 10 cm above the tankbottom you could never force fuel into the compensatingpipe as the fuel was flowing through the ventpipe leaving some 10 cm of water in the tankbottom saving the compensating system. This was  before pollution and environment questions was a topic. Anyhow see to it that your fuel ventingpipe is not leading all the way to the bottom
Tore

[tore]

Simon.
Compensating expansionbox.
As to my yesterdays post I have given it a second thought. I believe the device and connecting pipe on the picture is too small for being the box. Estmating the capacity of the tank to be some 12 tonnes of fuel I guess it should have a volume about 150-200 liters ( almost an oilbarrel).
Tore

[tore]

Simon.
Reverting to your drawing of the main ventconnection for saddle fuel/ballast tank 4 stb.and port. The intermediate valve is a blocking gatevalve for each saddle fuel/ballast tank permanently shut when in fuelmode. In view of a possible risk for somebody to ship this valve, I believe the wheel was removed.
Tore

[tore]

Trimvalve.
We are frequently missing a cross section drawing of the various components to get a better understanding how the various systems works, Simon has provided us with a genuine cross section of the doubleseated valve which clearly demonstrate the working of the valve. Although I believe the photo is from a IX, I guess it is the same for VIICs.
On the unusual photo below I believe you see a cut through of the aft port side of the control room showing the trimpump with the doubleseated trim valve.  The double seated valve could have only two positions, directing the water from fwd to aft or aft to fwd trimtanks. Allthough the display gives a first class demonstration of the working, it is an expensive way of showing it.
Tore

[NZSnowman]

Simon.
Reverting to your drawing of the main ventconnection for saddle fuel/ballast tank 4 stb.and port. The intermediate valve is a blocking gatevalve for each saddle fuel/ballast tank permanently shut when in fuelmode. In view of a possible risk for somebody to ship this valve, I believe the wheel was removed.
Tore

Fixed. Thanks, Tore.