Apparatus for monitoring suspended particles in a liquid

Claim 1

Apparatus for monitoring the presence of suspended particles in a liquid, comprising: means defining an examination chamber, inlet means at one end of the chamber for a liquid to be monitored, a wall defining a weir at the opposite end of the chamber, the examination chamber having a floor which is inclined to the horizontal, the weir defining a constant liquid level in the chamber in use of the apparatus, a housing located above the examination chamber and above the liquid level therein, a light source mounted in the housing, reflector means for directing a light beam from the source vertically downwardly in parallel rays for normal incidence into liquid flowing through the chamber to effectively prevent liquid surface reflection, and photoelectric detector means liquid-protectively mounted inside the housing directly vertically below the light source for detecting back-scattered light scattered in an inwardly upward direction from suspended particles illuminated by the beam in said liquid flowing through the chamber, the inclination of said floor being such that any of said light rays reflected normal to said floor is outside the field of view of said photoelectric detector means.