These mark-tubes are well-suited for flow measurements. The measuring rangein the centre of the capillaries has only approx. 10 µm wall-thickness.However, the funnels are made up of thick-walled material. It makes it mucheasier to assemble the double funnelled mark-tubes into a liquid closedloop.

To adapt these capillaries, thin hoses are suitable. They can beplaced with liquid Teflon (PTFE) on both sides of the funnels.

Following some underlying data about our double funnelled mark-tubes:

• funnel outside-Ø 3.0 mm
• funnel inside-Ø 2.4 mm
• total length 80 mm
• measurement range Ø 0.5/0.7/1.0 mm
• measurement range length 30 mm
• Substrate borosilicate glass ( 0500 )