As connection lines between leak detector and interstitial space plastic hoses/pipes or metallic pipes can be used.
Connection lines must be resistant to pressures and the stored product and have to fulfill explosion protection requirement if neccessary.
Over the entire course of connection lines, the full inner diameter shall be kept. Pressing and kinking has to be avoided.
All lines have to be protected in a suitable way against mechanical and thermal influences and placed with continuous slope towards the interstitial space.
For vacuum leak detection systems: in case of low points in the connection lines condensate traps must be installed in all low points in all lines.
The pneumatic connection lines are to be marked in colour to avoid mistakes:
suction/pressure line: white or clear
measuring line: red
exhaust line: green
The European standard for leak detectors orders for leak detectors using air as a leak detection medium an inside diameter of 6 mm and for leak detectors using Inert gas as a leak detection medium an inside diameter of 4 mm. These instructions are valid for distances between leak detector and interstitial space of up to 50 meter. In addition to that, the diameter of the connection lines has to be adequately enlarged.
SGB recommendation for leak detection systems based on air: up to 50 m: 6 mm internal diameter, up to 100 m: 8 mm internal diameter, up to 150 m: 10 mm internal diameter.
An overview of line and connector combinations can be found here: Suitable connectors for hoses and pipes