Gauge function-Differential Pressure Gauge

Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules


Dec 11, 2015
Not sure where to post this. The Me262 had a set of gauges called Differential Pressure gauges FL20515. My question is, did they function like a EPR gauge? Thanks for your help. Fl.20515 Differenzdruckmesser, 1944


  • Fl20515-2.png
    42.8 KB · Views: 17
Differential pressure gauges have two inputs. One input port is for the actual pressure sense like fuel pressure and the other input port is for a different pressure, usually lower then the first port. Like on a turbocharged engine, to get the correct fuel pressure reading, you need the gauge to know what the upper deck pressure is coming off the turbo as the fuel pressure regulator also has the upper deck pressure acting on the fuel pressure regulator. Depending on how the gauge is made, the lower pressure puts pressure on the measuring sensor diaphram inside the gauge. Conversely, the oil pressure does not need a differential pressure gauge as the oil pressure is not dependent on altitude or manifold pressure as fuel pressure is in a turbocharged engine.
I found a schematic of how the various gauges were attached to and monitored the BMW004. It is my limited understanding that a EPR gauge displays the ratio of two pressures, one on the inlet and the other near or at the outlet. If this is correct than the differential gauge seems to function in a similar manner. From what I can gather it seems that 0.4 was the "normal" reading. So going further then, it seems to me that the difference between the inlet and outlet pressures was this 0.4 kg/cm2. This is about 5psi. I have no idea if this reasonable for an engine such as the BMW004. Thanks for the dialogue.


Users who are viewing this thread