Abstract: Exemplary embodiments of the invention provide a plastic conduit or pipe having a free conduit cross-section, in particular for accommodating feeds, the free conduit cross section including multiple layers, wherein a first layer is formed from PVC, a second layer is made of a polymer and a bonding agent layer is arranged between the first and second layers.

Abstract: An apparatus for determining the effect of dilution and/or diffusion of the gaseous components of a gas flow passing through a gas permeable test object is claimed. The apparatus comprises a source of calibrating gas, a laminar resistance coupled to the source of calibrating gas with the gas flowing through the laminar resistance, and a volumeter is coupled to the laminar resistance for measuring the volume of gas flowing therethrough. The gas from the laminar resistance flows through the test object to a gas concentration measuring device for receiving and for measuring the concentration thereof. A bypass device is provided for bypassing the flow of gas around the test object, and a suction device draws gas from the source to the measuring device.