Hello Mr. Tore,
For the GW diesel engine - would it be fair to say the safety valve works as follows:
1. The safety valve provides for high pressure relief seen at the lube oil pump head.
2. If the oil filter was getting plugged then the oil pump would see an increase in back pressure.
3. At some point the safety valve would reach the 'Cracking Point" where there would be a small flow of lube oil to the collection tank. The cracking point is generally far below the popping point.
4. If the oil filter problem continues to get worse, then at some point the safety valve will do a full vent flow or "Pop."
5. The pipe for the safety valve is not huge, but it should be large enough to create a pressure drop.
6. The safety valve is designed so that it will not recover from a full vent flow (Pop) until the pressure went down below the cracking point.
7. The lube oil pipe to the servomotor and the governor should sense the pressure drop and react by shutting down the diesel engine.
The MAN diesel engine uses the safety valve to short the lube oil pump output to the lube oil input. I believe they are achieving the same result (a pressure drop). I have the schematics for the type IX U-Boat and the MAN 9 cylinder diesel engine and it does not have a reducing valve 1.5 < 3.0 atu in the lube oil system schematic.
I have done a lot of research on the safety valve...
If I assume the the GW 6 cylinder engine is at mid range rpm, then the attached lube oil pump pressure head is about 3 atu... Is that correct?
The reducing valve at 1.5 < 3 atu will create some back pressure when reducing its pressure output without an adequately sized vent line, but I guess the system can handle that back pressure with pipe lengths and passing through various components.
What do you think?
Kind regards,
Don_