Measuring head for in line determination of the size of moving particles in transparent media

Measuring head for in-line determination of the size of moving particles in transparent media, comprising a tube-shaped measuring head body which has a parallel-walled opening, open on one side, in the region of its front end, located in the measuring space, for holding an optical measuring point with two measuring windows, the optical measuring point consisting of an illuminating device arranged in an opening wall and a light receiving device provided in the opposite opening wall, the light receiving device is connected to an opto-electronic converter device, whereby the particle flow is located between the illuminating device and the light receiving device, the measuring head includes a rinsing device for cleaning the optical measuring point, whereby the rinsing device consists of a rinsing medium source, a channel leading as far as the opening inside the tube-shaped measuring head body for delivery of the rinsing medium, and discharge openings in the region of the opening,

• the rinsing device is characterized by a rinsing insert (9;
• 16) that can be inserted into, attached in, and replaced in the parallel-walled opening (3), the rinsing insert partially or completely supplements the cross-section of the tube-shaped measuring head body (1) in the region or the opening (3), seen in axial cross-section,
• the rinsing insert furthermore possesses an inlet opening (13) connected with the source of a rinsing medium by way of the channel (14) and with the discharge opening (7) that opens perpendicular to the measuring windows (4;
• 5) of the optical measuring point, and two discharge openings (15;
• 21) for the rinsing medium connected with the inlet opening, the discharge openings run perpendicular to the measuring windows (4;
• 5) of the illuminating device and the light receiving arrangement, respectively.