RF-DIF-BN50SI – see when the filter is spent
Our proven RF-DIF-BN50 disposable in-line filter with a silica-bonded element and an indicating dye. When red appears on the outside of the element, it is time to replace the filter – no guessing, no premature changes, no forgotten filters. The silica-bonded element stays white when heated or dried, so a clean filter never looks dirty. Formerly article no. RF-N05-CK-SI.
How the indicator works
The gas flows from the inside of the element to the outside. Captured liquid contaminants – typically oil aerosol and droplets – collect in the depth of the microfibre media and migrate outwards as the element loads up.
On their way they take up the indicating dye and carry it to the outer surface. A red outer surface shows that the element is loaded through its full depth and liquid would soon pass downstream.
That is why the orientation matters: with the wrong flow direction the colour would appear on the inside, where you cannot see it.
Element light over its full length – filter in service.
Liquid is held in the depth of the media – outside still light.
Red visible on the outside of the element – fit a new filter in the same orientation.
Technical data
| Article | RF-DIF-BN50SI (silica-bonded indicator version of RF-DIF-BN50) |
| Former article no. | RF-N05-CK-SI |
| Body | Nylon, transparent, welded |
| Filter media | Borosilicate glass microfibre, silica-bonded, encapsulated, with indicating dye – stays white when heated or dried |
| Grade | 50 – 99.99 % @ 0.01 µm |
| Element | 12 × 32 mm |
| Connections | 2 × hose spigot Ø 6.35 mm (¼″), bore Ø 3 mm |
| Dimensions | Length 82.25 mm, body Ø 25.40 mm |
| Rating | 110 °C @ 0 bar – 50 °C @ 8.5 bar (temperature limit set by the nylon body, not by the silica-bonded element) |
| Flow direction | Inside → outside (mandatory) |
Typical uses
- Protection of gas analysers and sensors
- Sample and purge lines
- Pneumatic instruments and small consumers
- Point-of-use oil and aerosol removal on compressed air and gases
Good to know
- Why silica-bonded? Standard binder can turn slightly brown when an element is heated or oven-dried – customers then think it is damaged or dirty. The silica-bonded element stays white.
- The indicator shows loading with liquid contaminants such as oil. It is not a differential-pressure indicator – a filter loaded mainly with dry dust can block without turning red. In dry, dusty gas keep a change interval.
- Other efficiency grades with indicator on request.
- Check the chemical compatibility of the nylon body with your gas. For higher pressures or temperatures we recommend a stainless steel housing with differential-pressure gauge.
Want to try RF-DIF-BN50SI?
Tell us your gas, flow, pressure and the equipment you protect – we confirm the right grade and send an offer.