Tores mailbox VIIC and VIIC/41 operation and technical details

[NZSnowman]

Simon.
Compensating water selector valve saddle fuel/MBT 2&4. May be an execution as below and possibly a removable T bar extension?
Tore

This was how I had always imagined it was. Under the deck and with a removable ‘T’ handle. I got the idea a few years back after seeing the same valve in your other post.

I will try to do some drawing of my idea and post them this weekend.

[Don Prince]

Hello Mr. Tore and Simon,


I looked at the starboard side of U995 and the hole for the compensating water to the sea are questionable... I have attached the images...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I have a very dumb question that is bugging me since this current discussion began...  Please see the drawing and straighten me out again. What am I missing?


Kind regards,
Don_

[tore]

Don, It is not a dumb question and the arrangement of the two pipes is an assumption. The only answer I can give is the footvalve of the system is a double seated valve with two possible positions either to connect the fueltank with the header tank in the fuel configuration to provide compensating water or to put the ballasttank in connection with the sea. The only reason I can see for the latter configuration is to have a relief/safety arrangement for a possible blowing of the ballast tank with the Kingstons shut thus prevent overstressing the tank. Otherwise you are right in you statement about the fuelcontamination prevention of the sounding system during fuelling.

Tore

[NZSnowman]

Tore, does the opening to the sea needs to be at the bottom of the saddletank?

In the photo below you can very clearly see a pipe opening (Blue arrow).

[Don Prince]

Hello Mr. tore,


I have a NAVPERS 16160 manual for the US Fleet Type Submarine and they have Ballast and Water Compensated RFO tanks as well.  They have a valve inside the pressure hull that channels the water to a pipe that extends to the bottom of the tanks.


I have a problem with Skizzenbuch pages 81 through 83 where  I'm not sure if it is accurate? I possibly need to change the drawings on all 3 pages and the text on page 83.


"The compensating water pipes goes from the header tank to a small chamber (about 1.5 % of the tank volume) at the bottom of the tank, from this chamber a short pipe goes into the tank bottom and an equalizing pipe directly to the sea. The two connections are controlled by a double seated selector valve operated from the casing. The valve has only two positions, either to the fuel tank or direct to the sea. When in the fuel oil tank configuration the Kingstons are shut and the selector valve open to the fuel tank and thus shut to the sea (see the diagrams on page 78)."


1. Indicates a small chamber near the bottom of the tank
2. A short pipe that goes to the bottom of the saddle tank
3. A equalizer pipe directly to the sea
4. The two connections are controlled by a double sealed selector valve from the casing
Plan 10 shows the selector valves (b), but there is no indication that the valve is internal to any tank. Thus the thought of the selector valve being under the deck casing, but I'm not sure...
I did a guess drawing with 1 pipe and the selector valve under the deck.  The selector valve has 3 positions:
1. Off
2. Water to the tank
3. Test/water overboard
What do you think?

[Don Prince]

Hi Simon,


Could you please email me that photo without the arrows if you have one?  I need a larger size for resolution if possible...

I pulled Skizzenbuch from my dropbox so I could make changes on pages 81 - 83 (I don't want my managing editor getting it yet)...

Regards,
Don_

[tore]

Don.
I Guess 4.    ...... double sealed selectorvalve......is a misprint. I am not sure of the three positions of the selector valve 1. Off?
I guess you have only two positions either to the tank or to the sea.
Tore

[Don Prince]

Hello Mr. Tore,


OK, I changed the drawing...


Regards,
Don_

[NZSnowman]

Hi Simon,


Could you please email me that photo without the arrows if you have one?  I need a larger size for resolution if possible...

I pulled Skizzenbuch from my dropbox so I could make changes on pages 81 - 83 (I don't want my managing editor getting it yet)...

Regards,
Don_

Sorry Don, that is the only one I have

I got it from Siara (http://models.rokket.biz/index.php?action=profile;u=44) many years ago. I never seen it in a book or anywhere on the Internet.

[tore]

Simon.
I don`t see any particular reason to have the outlet at the bottom of the tank, might be you have found a solution by your photo.
Tore

[Don Prince]

Hello Mr. Tore,


I uploaded Skizzenbuch back to dropbox.  If at all possible would you review pages 81, 82, and 83 because I modified your drawings and updated the text to reflect the changes... Actually there was not that much to change.


Regards,
Don_

[NZSnowman]

Here are some early modelling of the valve.


Fig. 1. Top view. Images has been resized. Click to view original image.


Fig. 2. Port view. Images has been resized. Click to view original image.


Fig. 3. Images has been resized. Click to view original image.


Fig. 4. Images has been resized. Click to view original image.


Fig. 4a. Images has been resized. Click to view original image.


Fig. 5. Deck hatch closed. Images has been resized. Click to view original image.


Fig. 5a. Deck hatch open. Images has been resized. Click to view original image.


Fig. 5b. Deck hatch open. Images has been resized. Click to view original image.

[Don Prince]

Hello Mr. tore,


If I remember correctly, you said U-926 Kya had a damaged MBT 3 which was done by accident...


OL Hellmut Rehren was the CO who joined the Kriegsmarine back in 1939 and worked his way up the ranks until 1943 when he became a OL. He was given command of U-926 in February 1945 and had to surrender his 1st command on 9 May 1945.  I'm willing to bet that he or his EO were NOT very happy about that prospect.


The type VII C has 12 HP storage canisters and it would be very simple to shut the Kingstons and the emergency vent valves and vent valves, and then blow MBT 3 while running on the surface to surrender with the hatches open.  If the pressure of 16 bars from the 1st attempt didn't blow the end caps off the ballast tank (not likely), then recharging the HP canisters and the 2nd 16 bars surely would do the job...


Formula...


PV = PV


Canister pressure is 201 bars at 3.936 m³
MBT 3 volume is 47.75 m³ (Pressure would be = 16 bars) if all is blown into the tank.


Regards,
Don_

[tore]

Don.
I`ve checked Skizzen book page 81 thru 83 and have marked off my findings as per images below. I guess a misunderstanding has ocurred as to the gate valves in the MBT 2&4 ventingsystem. You don`t have both gatevalves and cumbersome blindflanges in the system, you have gatevalves instead of cumbersome blindflanges. As you know a gatevalve is almost  an easy removable blindflange.
Tore