Abstract: The invention relates to a connecting flange for analytical instruments for investigating a fluid flowing in a pipeline, having a disk-shaped installation ring which comprises two substantially planar end surfaces, an outer jacket surface and a inner jacket surface which defines an axial passage, the installation ring having at least one radial drillhole opening into the outer jacket surface, to which an analytical instrument can be connected and the process for installing the instruments. The invention also relates to an analytical probe having such an analytical instrument, and also to the use of this analytical probe in a process for preparing alkyl (meth)acrylates by reacting (meth)acrylic acid with alkanols.

Abstract: The invention relates to a connecting flange for analytical instruments for investigating a fluid flowing in a pipeline, having a disk-shaped installation ring (11) which comprises two substantially planar end surfaces (12, 12?), an outer jacket surface (13) and a inner jacket surface (14) which defines an axial passage (15), the installation ring (11) having at least one radial drillhole (16) opening into the outer jacket surface, to which an analytical instrument can be connected. The invention also relates to an analytical probe having such an analytical instrument, and also to the use of this analytical probe in a process for preparing alkyl (meth)acrylates by reacting (meth)acrylic acid with alkanols.