Oxygen in U-boat - U-boat Officer's Reply

[SquareSteelBar]

Originally Posted by Stiebler

@Oblt Strand, SSB:
Lt Paas says in his two different accounts:
30 atmospheres for compressed air.
20 atmospheres for compressed oxygen...

..."It is correct that on board the submarines, besides the compressed air-bottles, had also bottles with pure oxygen. Both bottle-types had a pressure of 20 atmospheres = Bar..."

[Stiebler]

@SSB:
Yes, you are correct, he seems to have changed his mind a little from the first communication.

Stiebler.

[JayDee]

After a short look in my books, there seems to be a bit of confusion here...
I am quite sure that the high pressure air system actually had 205 atü = 205 bar.
For the oxygen bottles I found 150 atü (for Type XXI).

Data for Type IXC:
- High pressure air: 5840 l in 16 bottles @205 atü
- High pressure compressors: 1x 8,5 l/min @205 atü Diesel, 1x 14 l/min @205 atü electric
- Oxygen: 650 l in 13 bottles

Data for Type XXI:
- High pressure air: 7660 l in 23 bottles @205 atü
- High pressure compressors: 2x 10 l/min @200 atü Diesel, 1x 16 l/min @200 atü electric
- Oxygen: 1500 l in 30 bottles @150 atü
(U-2513, U-3008: 1200 l in 24 bottles, U-2540: 1150 l in 23 bottles)
- Some more oxygen in chemically bound form ("IG-Briketts")

Some general data for Type XXI (probably partly also valid for other types):
- Soda lime cardridges were used if CO2-level went above 1,5% (after about 11 hours if crew was not very active)
- Enough soda lime for about 19-23 days was on board)
- Oxygen was added if oxygen level dropped to 17% (after about 27 hours if crew was not very active)
- Oxygen supplies lasted for about 150 hours / 6 days

EDIT: Verification:
Type IX high pressure system: http://www.uboatarchive.net/DesignSt...ypeIXC-S49.htm
Type IX CO2 removal / oxygen system: http://www.uboatarchive.net/DesignSt...ypeIXC-S38.htm
Type XXI high pressure system: http://www.uboatarchive.net/DesignSt...ypeXXI-S49.htm
Type XXI CO2 removal / oxygen system: http://www.uboatarchive.net/DesignSt...ypeXXI-S38.htm

Greets, Jan

[Stiebler]

@JayDee:

That is extremely valuable information, JayDee, and the U-boatArchive.net references are clearly to near-contemporary (1946) American reports taken from seized German documents.

This information must be much more accurate than that remembered by survivors after the passage of 60 years.

Eg, for the Type IX boats, "For oxygen renewal a total of 13 flasks, each containing 50 liters of oxygen under 160 atmospheres (2275 p.s.i.) pressure, are installed. 44 sets of emergency breathing apparatus are carried on board."

Well done!

Stiebler.

[LGN1]

Hi JayDee,

could you please tell me the titles of your books? I'm always looking for good books about u-boats (operations and technical data) and I'm wondering whether you can recommend some books I don't know yet. Thanks!

Regards, LGN1

PS: The VIIC handbook mentions 10 oxygen bottles with 50ltr and 150atü. Unfortunately, this data does not help us much because we don't know accurately the volume of the boats and the oxygen consumption of the crew

@Stiebler: I meant the 1940 Norway campaign (Weserübung).

[JayDee]

Glad I could help you!

@LGN1:

Eberhard Rössler:
- Geschichte des deutschen U-Bootbaus, Vol. 1 & 2
The "standard" literature. I think this is (or was) available in English, too.

The next ones are more a reference if you want to built a model of a certain uboat, lots of pictures, some plans, some technical data, but not a lot of text. Not available in English IIRC. These are the ones I have:

Fritz Köhl, Alex Niestle: Vom Original zum Modell:
- Uboottyp VIIC
- Uboottyp IXC

Fritz Köhl, Eberhard Rössler: Vom Original zum Modell:
- Uboottyp XXI
- Uboottyp XXIII

Eberhard Rössler: Vom Original zum Modell:
- Vom Original zum Modell:Uboottyp XVII - Walter-Uboote -
- Die grossen Walter-Uboote, Typ XVIII und XXVI

Jan

[JayDee]

Originally Posted by LGN1

The VIIC handbook mentions 10 oxygen bottles with 50ltr and 150atü. Unfortunately, this data does not help us much because we don't know accurately the volume of the boats and the oxygen consumption of the crew

Sorry, I can only help with some vague volumes...
Pressure hull of Type IXC: 748,35 m³ (- 72,94 m³ of internal fuel / oil / trim water tanks IF these are full, - unknown volume of internal installations: "x")
Same data for IXC/40: 761,50 m³ (- 76,37 m³ - "x")
For VIIC: 674 m³ (- (97,73 m³ + volume of Tauchzelle 3, unknown to me) - "x")
For XXI: 1161 m³, or 898 m³ with all internal installations. Sadly, I don't know if these 263 m³ or about 23% include any (full) tanks, or if it is just the internal installations, machinery etc. (and therefore the "x" in the calculations above).

Jan

[Ligne Maginot]

Originally Posted by Stiebler

@Everyone:
Could we please keep this thread on-topic, for the benefit of any future researcher trying to discover authentic eye-witness information about U-boats? That is why I started this thread. Many thanks.
Stiebler.

I'm sorry, but it is a categorical imperative to keep it afloat (almost kantian meaning).

Best regards.

[JeromeHeretic]

Look at this movie:

They talk about high pressure and low pressure system. High pressure was used in big depth, low pressure system was used in small depths, but both systems was suplied from the same high pressure tanks, low pressure was created from high pressure by pressure dividing valve.

Yes, of course this movie is about US submarines, but in german it was principialy done in the same way. Maybe values of used pressure was a bit different.

[Sailor Steve]

[BigWalleye]

Steve, I think Ligne Maginot was intentionally necroposting to resurrect this thread. It's a very interesting and useful thread. I never would have searched for it, because I didn't know that such information existed. But I was glad to see it and learn from it. Information like this, especially the first-person recollection, is precious and easily lost. I realize SubSim has to pay for bandwidth, but IMO, this was a worthwhile use. To stand behind my words, I just kicked in another sawbuck.

[Ligne Maginot]

Maybe Steve in his infinite wisdom already knew this information, but I don't. Nor the new members. If there is a problem, for my next subscription, I will pay double.

Attentively Doctor Frankenstein.