3.　Characteristics of the system on experiment and actual ships

　

3.1　Experimental research

The followability of the air and oil pressures to the water pressure were measured by the experiment of AIRGUARD 3AS as shown in Fig.7. The air and oil pressures follow up meaningfully in case of not only "without shaft vibration" but also "with shaft vibration" according to the change of the water pressure. Where, #1-Dummy (Water) and #3-Dummy (Oil) correspond to the pressures of the sea water and stern tube respectively.

(1)　Without Shaft Vibration

(2)　With Shaft Vibration (15Hz±0.4mm)

Fig.7　Experimental Data of Pressure Follow-up

The temparatures of seal rings were also measured as shown in Fig.8. Irrespective of the change of the sea water pressure, the temperatures are always constant and sufficiently low, because of the constant differtial pressures for each seal ring, -15 kPa for #1 S/R, 40 kPa for

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