US 4,687,327 AGranted

Oil mist monitor

AssigneeThe Dow Chemical Company

InventorMichael R. Wheeless

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Abstract

An instrument for measuring opacity of oil mist for lubrication purposes is set forth. In the preferred and illustrated embodiment, the apparatus is preferably installed in a pipe cross, opposing legs of the cross conduct oil mist past the opposite two legs supporting an opacity measuring system. Utilizing a bridge voltage supply to power an amplifier forming a reference voltage for reference diodes, a first photo cell is provided with a reference light from LED created light directed to the reference. A second LED directs light through the oil mist. The quantity of light is measured by a second photo cell reflecting the light absorbence of the sample, and the output of the two measuring devices is determined in a differential amplifier, driving a meter movement. The direct current signal is at a safe current range for use of the transmitter in a hazardous environment and is inversely proportional to the percent transmission of the signal.

For use with an oil mist genrating apparatus forming an oil mist conveyed along a conduit with an air flow to apparatus using such an oil mist, oil mist monitoring apparatus comprising:

(a) a laterally extending open interior housing means adapted to be positioned at a location to conduct air borne oil mist thereacross;
(b) first monochromatic light forming means in said housing means for forming light illuminating said housing means across the oil mist passing therethrough;
(c) first light detector means in said housing means located to detect light from said monochromative light forming means across the oil mist passing through said housing means and forming a first output signal;
(d) a cooperative joinder to said housing means including, first and second separate flange mounting means adapted to join to said housing means to position and locate said first monochromatic light forming means and said first light detector meansand for directing light across said housing means;
(e) second light forming means providing reference light wherein said first light forming means and said second light forming means are similar to each other to form light in equal quantity in response to equal light forming currents;
(f) second light detector means positioned to detect reference light from said second light forming means;
(g) light opaque container means enclosing said second light forming means and said second light detector means to prevent internal light from entering therein and further positioning said second light detector means to view said second light forming means and forming a second output signal;
(h) means mounting said first and second light forming means in sufficient proximity to each other for exposure to common temperature variations;
(i) circuit means electrically comparing said first and second output signals to provide an output signal inversely related to opacity of the oil mist in said housing means;
and
(j) output means provided with said output signal to indicate oil mist opacity.

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Abstract

Claims15