The Oil mist detector takes continuous samples from the main engine crankcase and check whether the sample concentrations of mist are well below the level at which a crankcase explosion can take place. The oil mist is drawn into the instrument with the help of small fan, which takes suction from each crankcase through sampling tubes provided on each crankcase.
The oil mist detector consists of a small rotator with which it takes sample from one cylinder at a
time and the rotator then turns to the next after approximately 4 seconds. The sample from the rotator goes to the measured cell and the reference cell takes sample from rest of the crankcase to evaluate the difference in oil mist.
An overall mist density of the crankcase is also measured by comparing the samples with the fresh air once every rotation of the sampling valve is done. A beam of light from a common lamp is reflected through mirrors and output is measured from a photocell.
Under normal conditions the output from the reference and measured contact is same and hence no deflection is measured. However, a deflection in the output gives an alarm indication and the valve rotator stops at position to know which chamber has high mist concentration.
The oil mist detector consists of a small rotator with which it takes sample from one cylinder at a
time and the rotator then turns to the next after approximately 4 seconds. The sample from the rotator goes to the measured cell and the reference cell takes sample from rest of the crankcase to evaluate the difference in oil mist.
An overall mist density of the crankcase is also measured by comparing the samples with the fresh air once every rotation of the sampling valve is done. A beam of light from a common lamp is reflected through mirrors and output is measured from a photocell.
Under normal conditions the output from the reference and measured contact is same and hence no deflection is measured. However, a deflection in the output gives an alarm indication and the valve rotator stops at position to know which chamber has high mist concentration.
Comments