These tubes are composed of a surface profile wire that is spirally wrapped around axial support profiles and attached to each other by resistance welding.
Direction
The direction of the filtering flow determines the position of the surface profiles in relation to the support profiles.
The flat side of the surface profile is on the outside of the tube when the flow is from out to in (FOTI)
The flat side of the surface profile is on the inside of the tube when the flow is from in to out (FITO). This is also called a reversed profile.
Possibilities
The designation of a slot tube with radial external wire describes its construction as follows:
Surface wire / Support wire x number of support wires
Example: 12S/Q25 x 8
This means that the profile wire is 12S. The support wire is Q25 and there are 8 support wires, equally spaced around 360°