Don.
Regulating tanks.
The description used by quoting the translation of the German divingmanual resembles what we previously have discussed under Q tanks nothing particularly wrong but difficult to understand for the readers speaking English.
I have made another attempt to describe the regulating tank system as follows:
The regulating tanks are provided for compensating the submarines daily change of weight and buoyancy due to consumption, leakages, seawaterconditions (salinity and temperature) and displacement changes with regards to compression of the pressurehull during deep diving.
There are four regulating saddletanks, two ( reg. tanks 2 port and starboard) each having a capacity of 7.600 m3 and two (reg. and f.oil. tks no 1 port and stb.) each having a capacity of 4.700m3. The latter tanks can be used as reserve fueloil tanks.
All the tanks are made pressureproof having a testpressure of 14 kg/cm2. If the differential pressure between two adjacent tanks exceeds 14 kg/cm2 f. inst in the reg. tank 2 between Q and reg./ fuel oiltank 1 the two latter tanks should be put under some pressure to avoid exceeding the max. differential pressure and rupture of the bulkhead between the tanks.
All the tanks have graded waterlevel gauges in the controlroom showing the prevailing watercontents. All tanks can be operated by the main drainage pump, aux trim and drainage pump as well as airpressure.
When diving a pair of regulatingtanks are made ready for flooding and shallow water discharging by air. The other tanks connected to the main drainage pump in two stage configuration ready for for discharging at greater depths and the tanks are put under airpressure app. 10-12 kg/cm2.
When cruising at periscope depth a decreasing of weight is done by admitting pressure air to the tank in shallow water configuration pushing the water out of the tank thus avoiding to use the main drainage pump set to deep discharging of the deepdiving regulating tanks.
An increasing in weight is done by filling the tanks via the fine filling seavalve and flowmeter.
When going deeper the pressurehull is compressed and the displacement is becoming smaller hence the buoyancy is less. This has to be compensated by discharging water from the regulating tank in deep dive mode. The required capacity would be appr. 100l/10m, but usually more is discharged to compensate for leakages.
Plate 7 shows the regulating tank system, however the real system deviates somewhat from plate 7.
Below I have tried to sketch an image to show how I assume the system works.
The fuel/regulating tank 1 port and stb. (red) are selected as the flooding/ discharging shallow water tanks. Flooding is done via the fine flood seavalve and meter, the discharge is done by admitting air pressure to the tanks (red pipelines), forcing the water either through the normal sea valve or the seavalve to MBT 3.
The regulating tanks no 2 port and stb. (yellow) are in deep water configuration having the main drainagepump impellers in series and the tank airpressure up to 14 kg/cm2. Discharge pipe (yellow) directly via the normal overboard valve or via MBT 3.
The above suggestion is one of several possible configuration indicating the working of the system. I have left out the fuelconfiguration of the regulating/ fueloil tanks for simplification.
