DR-3 Design Report-3 Why Use Analytical Fittings Instead of Industrial Ones

Why use analytical fittings instead of industrial ones and why use improved analytical fittings instead of standard analytical fittings in high performance systems ?

The well known double ferrule assembly has a ‘’swaging’’ action, i.e. it compresses the tube in some points and increases tube outside diameter beyond those points, as shown in Figure 1. This design is ideal for industrial application like in high pressure system and/or when there is a high level of vibration. The oversize section of the tube beyond the front ferrule makes it very difficult to come out of the fitting even if the nut loosens over time. This creates a safe assembly. This type of fitting is virtually used in all process plants today. The general acceptance of this design and its ease of availability have led analytical system designers to use it also in analytical instruments and sampling systems. These designs have worked well for many analytical systems by early standard and the available instrument limit of detection.

However by today standards such fitting design appears to be problematic for instrument manufacturers, system integrators and sampling system builders.