Radial external wire
Radial external wire
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.
There are 2 types:
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°
Standard constructions (1)
| Profile | Support wires | Min. diameter | Min. slot width (2) |
|---|---|---|---|
| in mm | in mm | ||
| 4S | Q22 or Q25 | 20 | 0.015 (3) |
| 5S | Q22 or Q25 | 20 | 0.015 (3) |
| 6SC | Q22 | 20 | 0.015 (3) |
| 10S | Q25 | 20 | 0.015 (3) |
| 11S | Q22 or Q25 | 21 | 0.015 (3) |
| 12S | Q25 | 21 | 0.015 (3) |
| Q35 | 30 | 0.05 | |
| 18S | 22S or Q35 | 30 | 0.05 |
| Q25 | 25 | 0.03 | |
| D45 | 300 | 0.2 | |
| 10x3 | 300 | 0.2 | |
| 22S | 22S or Q35 | 45 | 0.05 |
| D45 or 10x3 or 25x3 | 300 | 0.2 | |
| 28S | Q35 | 215 | 0.2 |
| D45 or 10x3 or 25x3 | 300 | 0.2 | |
| 34S | Q35 | 300 | 0.2 |
| D45 or 10x3 or 25x3 | 300 | 0.2 | |
| 42S | Q35 or D45 | 300 | 0.2 |
| 10x3 or 25x3 | 300 | 0.2 |
(1) Special constructions are possible on request
(2) The minimum slot will increase when the diameter becomes bigger
(3) Depending on the slot tube diameter
Standard finish of the slot tubes:
- Grinding of the end surfaces
- Removal of loose profile ends
- Degreasing and pickling
Standard tolerances:
| Diameter < 164 mm | +/- 0,3 mm | |||
| Diameter >= 164 mm - <= 301 mm | +/- 0,5 mm | |||
| Diameter > 301 mm | +/- 2,5 mm | |||
| Length for OD <= 301 mm | +/- 2 mm | |||
| Length for OD > 301 mm | +/- 4 mm |
Special features
Variable slot openings are possible on all diameters
Continuous cylinders: by using a lot of support profiles, an axial slot can be obtained. These filter elements are called continuous cylinders.
Optional finish for the slot tubes:
- Fastening of loose profile ends
- Removal of burrs at profile ends
- Post machining for tighter tolerances
Slot tubes with end pieces:
Standard end pieces are always welded onto the support profiles. Other custom made end pieces can be fabricated on demand.
To protect slot tubes against collapse, reinforcements are optional.
Reinforcing a slot tube is possible through:
- More or stronger support wires
- By adding internal reinforcement
Support elements
If the slot tubes are used as a carrier for another filter medium, for example textile, round wire can be applied. These support elements can be welded with 1, 2 or 3 wires next to each other.
Technical information
- Diameter: ± 25 to 40 mm
- Standard profiles
- Spiral wire: Ø 0.8 mm
- Support wire: Ø 2 mm
Compared with conventional support elements (such as perforated tubes, wire mesh,…) Trislot support elements have the following advantages:
- A smaller contact between the support tube and the filter media results in a more active filter area, which creates a larger active filter media and a lower pressure drop.
- Thorough cleaning by back flushing is possible.
- Strong mechanical constructions
- Larger open area