> Securiton DFU 911S dust filter unit with protection flap
> Source: https://pap.fi/en/tuote/securiton-dfu-911s/
> Full site in machine-readable form (in Finnish): https://pap.fi/llms-full.txt
> Pages in English: https://pap.fi/llms.txt

# Securiton DFU 911S dust filter unit with protection flap

Product code 61412

Dust filter installed in the sampling pipe for dusty and dirty areas. Extends smoke sensor service life and reduces false alarms. The flap triggers a fault if the filter is missing.

-   Replacement cartridge RFC 911
-   Filter service life monitoring in the ASD detector
-   Spring flap triggers an airflow fault if the filter is missing (NS 3960:2019)
-   Not for deep-freeze, outdoor or very humid areas

## Product description

DFU 911S is Securiton’s dust filter unit, installed in the sampling pipe in dusty or dirty areas. According to the manufacturer, it significantly extends the service life of the smoke sensor, airflow sensor and fan and reduces false alarms. The two-part housing opens with lock clamps for replacing the RFC 911 cartridge. The DFU 911S has a spring flap in the housing base that triggers an airflow fault when no filter is fitted (requirement of NS 3960:2019). The flap also protects the detector during cartridge replacement.

The filter is preferably installed below the detector, immediately before it: at least 10 cm away for ASD 531/532 and at least 20 cm for ASD 533/535. The detector can monitor the application-specific service life of the filter and signal a fault when it needs replacing. According to the catalogue, the unit is not suitable for deep-freeze, outdoor or very humid areas.

## Technical data

- **Product code:** 61412
- **Manufacturer:** Securiton
- **Manufacturer’s code:** DFU 911S (11-2300103-01-01)
- **Product group:** Aspirating smoke detection › Filters and maintenance
- **Replacement filter:** RFC 911
- **Pipe connection:** Ø 25 mm
- **Operating temperature:** 0…+60 °C
- **Material:** ABS blend, UL 94-V0
- **Dimensions:** 210 × 111 × 137 mm (H × W × D)
- **Weight:** 490 g
- **Compatibility:** ASD 531, ASD 532, ASD 533, ASD 535, ASD 2000

## Documents

Original manufacturer documents (PDF).

### Technical datasheets

-   [Datasheet: DFU 911, DFU 911S](https://pap.fi/liitteet/valmistajat/securiton__DFU911_DS_T140705en_b.pdf) PDF · English · 191 kB
-   [Product catalogue (series): sampling pipe materials ASD 531–535 (DE/EN)](https://pap.fi/liitteet/valmistajat/securiton__ASD531-535_AM_T131194ED_k.pdf) PDF · multilingual · 1.4 MB
-   [Product catalogue (series): SecuriSmoke ASD 2026 (Securiton)](https://pap.fi/liitteet/valmistajat/securiton__SecuriSmoke_ASD_PC2026_F301en_c.pdf) PDF · English · 2.5 MB

### Brochures

-   [Brochure: DFU 911, DFU 911S](https://pap.fi/liitteet/valmistajat/securiton__DFU911_DFU911S_FLYER_en.pdf) PDF · English · 1.1 MB