Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

So, in order to drain the exhaust manifold you will need to open the venting valve (n) and the Drain valve (o) on the exhaust manifold...


Don_

[tore]

Don.
I guess the venting valves belongs to the anticorrosion system. E.g. you are draining the seawater in the coolingmantels. We did not make use of the anticorrosion system and had only minor problems.
Tore 

[Don Prince]

Hello Mr. Tore,


I guess where my confusion begins about the cooling water system involves the jacketing of the exhaust manifold. Some of the draining valves are taking water and possibly some air from the cooling water jacket space. However, the vent and the drain for the exhaust manifold has to pass through the water cooling jacket to the inner chamber of the manifold in order to function properly.


Therefore, valve (n) the vent valve line, the safety valve line, and the drain valve (o) line must pass through the water cooling jacket into the exhaust manifold chamber in order to function properly...


What do you think?


Regards,
Don_

[tore]

Don.
This is only for draining the sea cooling mantels in the system not the possible seawater from the leakages of the main exhaust flapvalves. In a confined space like the coolingmantels you need a vent to be able to drain properly.
Below is an image of the reliief valve of the exhaust reciever, as you see pretty close to the maneuverstand and could be unpleacent for the man operating the engine.

[Don Prince]

Hello Mr. Tore,

I have the same view of the Diesel engine that you have item listed the components in your previous posting. However, with the magic of the Paint.net application, I can bring some components to light! Could what I have uncovered be the components in Plate 13 that I had marked as well? The lower handle looks like a black "L" shaped handle and the drive shaft extends under the diesel engine exhaust manifold end cap near the operator.

Regards,
Don_

Addition:
If you look at this drawing that you had done several years ago (last posted). The exact same valves are identified as the vent valve (n) and drain valve (o). However, I believe these valve actuators are located near the safety valve at the forward end of the exhaust manifold, and not in the relative position as shown in the schematics.

[Don Prince]

Hello Mr. Tore,

The top valve in my previous posting looks to be a cooling water drain valve per Simon's drawing (see the red circle)...

Regards,
Don_

[Don Prince]

Hello Mr. Tore,


Do you have a photo of what valve is connected to pipe #7 on the u-historia photo?


Regards,
Don_

[tore]

Don
I have been looking into my files and the only I found is the image below.
Tore

[tore]

Don.
Somehow the lower part  of my image was cut off. Here is another try.
Tore

[Don Prince]

Hello Mr. Tore,

I didn't realize that U-historia has two #7 items listed...  I took one of Simons drawings and it looks like the line in "Yellow" drains the the Main internal exhaust valve chamber of flooded seawater???

I was just attempting to get that established...

Regards,
Don_

[tore]

Don,
I leave it to Simon to comment on his drawing, but guess you remarks on draining the snortmast and startig is correct with a few minor things. Basicly the starting procedure is the same as for any start. As you normally shall have some water in the chamber between the outer and inner main exhaustvalve. However if you have a massive intrusion of water you might experience a filling of the exhaustmanifold with a possible filling of some cylinders as you have explained. In any start you blow through the cylinder with open indicators cocks and the engine shall turn a few revs, you don`t  open the indicatorcocks to "make it easier to turn the engine", the reason is to blow out possible water in the cylinder through the open indicator cocks to prevent waterstroke. The starting airpressure of 30 kg/cm2 is ample to run the engine easy on air only, but you want to prevent water strokes, hence you want to get rid of the water in the cylinder which might created a major damage by a reciprocating engine. Only in extreme cases you crank the engine by hand, not normally, as air shall do the job easy having an experienced engineer at the starting handle bowing out the trapped water in the cylinders flooded.
I noted some place you mentioned we dived with the snortmast raised, that is a misunderstading, we normally raised the snortmast submerged but raised the mast for maintenace surfaced, see the image below, however we did we never run the engines with the mast raised on the surface as the mast did not have any cooling and the greaseingpoints could be ruined.
Tore

[Don Prince]

Hello Mr. Tore,

Thank you for the corrections...

#1) Starting the Diesel engines with controlled air pressure makes perfect sense (The only cylinders that should be flooded with seawater had their exhaust valve open when the Diesel engine was stopped - flooding occurred via the cylinder head exhaust chamber and the exhaust manifold seawater intrusion)...

1. HP air is admitted on a piston in a power stroke (drives it down the cylinder liner & turning the crankshaft).
2. Any piston in the exhaust stroke will force any seawater out of the liner via the open exhaust valve.
3. Any piston in the intake stroke will take in pressure hull air via the open intake valve.
4. Any piston in the compression stroke will force air out through the open test cock.

After the first 2 full turns of the crankshaft there should be practically no more water in the flooded cylinder liner depending upon the flooding state of the exhaust valve chamber in the cylinder head. Eventually, all flooding water will be forced into the exhaust manifold with HP air and drained into the bilge via the open drain valve...

#2) OK... You raised the schnorchel mast submerges as Aaron suggested. So, you had to drain the Schnorchel mast air supply section into the bilge to clear the water and open up the air supply.

The schnorchel exhaust mast is still flooded up to the tower deck exhaust shut-off valve? U-995 had the Type II schnorchel with the bend in the air supply, and the straight connection from the schnorchel exhaust shut-off valve and through the blowing valve and then to the Main External Exhaust Valve. The exhaust system on the Type II schnorchel doesn't seem to have a draining capability? 

This was the question that I was attempting to understand... What was the starting procedure to deal with the flooded schnorchel exhaust system at the schnorchel exhaust shut-off valve?

Regards,
Don_

I thought that just starting the Diesel engine on air like normal, and when the internal exhaust system got up above 0.5 atmospheres (like blowing the ballast); then opening the Schnorchel exhaust shut-off valve and switching to fuel oil (ignition)?

However, Aaron has documentation of a special HP airline attached to the exhaust manifold to blow the schnorchel exhaust mast...

[tore]

Don.
The snort exhaustpipes have indeed a draining capacity as they are connected via shut off valves to the drainchamber between the inner and outer main exhaustvalves port and starboard. When draining the raised snortmast you can open one of these shut off valves and drain the water into this drainchamber and you have a normal situation like a leaking outer main exhaust flapvalve, hence you drain the water in the drainchamber to the bilge and discharge it overboard.

Tore

[Don Prince]

Hello Mr. Tore,

I agree that the drain capacity is there as you described... However, the schnorchel exhaust pipe outlet is about 0.5 meters below the seawater's surface level. You can drain the schnorchel's exhaust mast all day and never empty it because it will constantly be refilled by the surface water! Therefore, the Schnorchel's exhaust mast must be blown and then start the Diesel engine immediately to maintain the opened exhaust capability with the exhaust pressure...

Regards,
Don_

[Raymic1]

Hello Mr. Tore and Don
Hope you are all well?
During my research, I noticed these brackets.
I have asked this question recently on some Uboat Facebook sites and even the curators of U995 are unsure as to what these brackets on U995 were used for.
I have identified 3 of them so far onboard U995 from pictures, one under the Switchboard, one in the Galley, and One in the Forward Torpedo Room. There may be more I haven't found as yet.
No one is 100% sure if they are Kriegsmarine or Norwegian add ons.


And I see on my U570 Photo that there is NOT a bracket, although U570 Switchboard is early war Round type and U995 is late war Rectangular.


Some suggestions have been


1.Original Fire Extinguisher holders, either Kriegsmarine or Norwegian,  although they seem a bit small
2.Flashlight holders, although the Kreigsmarine Flashlights were generally square shaped.
3.Filters or spares holders
3.Crew Emergency Oxygen holders.


Can you shed any light on this mystery bracket at all?
thanks
Raymic (Mike)