DSP Couplings

A DSP coupling (Demi-raccord Symétrique à Pression) is a French-standard fire hose fitting conforming to NF S61-704 (delivery) and NF S61-705 (suction). It is the primary fire hose coupling standard throughout France and Francophone markets. DSP couplings are symmetrical — both halves are identical, so any DSP coupling connects to any other DSP of the same size without orientation checking.

The defining feature of DSP couplings is the built-in self-sealing valve. Every DSP coupling half contains an internal valve that opens automatically when two halves are connected and closes automatically when they are separated. When disconnected, the valve seals the open end of the hose — no water escapes from either half. This means a charged, pressurised hose line can be disconnected and reconnected without stopping the pump, without losing water, and without creating water hammer. No other common fire hose coupling standard (Storz, BS336, Barcelona, Gost) includes this feature as standard.

The full CA-FIRE firefighting coupling range includes DSP alongside all other major international standards.

CA-FIRE manufactures DSP couplings in three sizes:

DSP40 — Lug Ø 92 mm: smaller delivery coupling for 38–45 mm bore attack hose. Used on first-intervention hose reels, lightweight attack lines and building fire hose cabinet reels throughout France. Standard for French residential and commercial building fire protection systems.
DSP65 — Lug Ø 116 mm: larger delivery coupling for 65–75 mm bore main attack hose. The most widely used DSP size in the French fire service (Sapeurs-Pompiers), found on all fire truck primary attack lines and building wet riser connections. DSP65 is the dominant size in Francophone fire markets.
AR100 — Lug Ø 160 mm: large-bore suction coupling to NF S61-705 for 100–110 mm bore suction hose. Used on fire pump inlet connections from open water sources. Less common than DSP40 and DSP65 but required for large pumping appliances and portable pump systems.

For most procurement enquiries serving the French fire service or Francophone building market, DSP65 will represent the majority of volume, followed by DSP40 for first-intervention hose reels.

Yes — provided both couplings conform to NF S61-704 (DSP40 or DSP65) or NF S61-705 (AR100) and are the same size, they will be dimensionally interchangeable for connection and disconnection regardless of manufacturer. The lug geometry, locking ring dimensions and face seal seat are defined in the French standard precisely enough that compliant couplings from different manufacturers will physically connect.

However, it is important to note that the self-sealing valve mechanism must also be functional for the coupling to perform correctly under operational conditions. CA-FIRE DSP couplings are function-tested to verify both the dimensional compliance and the valve operation. When purchasing DSP couplings from any supplier, confirm that the self-sealing valve mechanism has been tested and is functional — not just that the coupling is dimensionally compliant.

DSP40, DSP65 and AR100 are three different sizes in the DSP/NF S61 family — they are not interchangeable with each other. The lug diameter is different for each size (92 mm, 116 mm and 160 mm respectively), and a DSP40 coupling will not engage with a DSP65 coupling, and vice versa.

Additionally, DSP40 and DSP65 are delivery couplings to NF S61-704 (designed for positive pressure / pressurised hose service), while AR100 is a suction coupling to NF S61-705 (designed for negative pressure / vacuum suction service). The AR100 has a heavier body construction to resist vacuum collapse on large-bore suction hose. Using a DSP40 or DSP65 delivery coupling on suction hose is not recommended as they are not rated for sustained vacuum service.

When specifying DSP couplings for a project, always confirm the size and application (delivery or suction) with reference to the project's fire protection schedule.

DSP to BSP thread: CA-FIRE manufactures DSP female thread (DSPF) and DSP male thread (DSPM) adaptors in DSP40 (G1½", G2") and DSP65 (G2½", G3") with BSP thread ends. These allow DSP-coupled hose to connect to BSP-threaded pump outlets, nozzles and landing valve connections — the most common connection requirement in French fire system installations.

DSP to Storz: DSP and Storz couplings use incompatible connection geometries — a DSP65 coupling will not connect to a Storz DN52 or DN65 coupling without an adaptor. Mixed DSP × Storz adaptors are available from CA-FIRE on request for export projects requiring compatibility between French and European standard hose.

DSP to Barcelona: Similarly, DSP and Barcelona couplings are not directly compatible. Mixed DSP × Barcelona adaptors are available on request for projects serving both French and Spanish-speaking markets — common on infrastructure projects in North Africa.

DSP coupling maintenance involves two main components: the face seal (the gasket between the two coupling halves at the interface) and the internal valve seal (the seal on the self-sealing valve mechanism inside the coupling body). Both seals are NBR as standard and are consumable maintenance items that should be inspected and replaced at regular intervals in accordance with French fire service maintenance schedules.

Common causes of DSP coupling failure: valve seal wear causing the valve to leak when the coupling is disconnected (water dribbles from the open end); face seal deterioration causing leakage at the coupling interface when connected; and locking ring wear causing the coupling to release under pressure. All three issues are addressed through routine seal replacement.

CA-FIRE stocks replacement face seals (code B5205xxx) and valve seals (code B5206xxx) for DSP40 and DSP65 in NBR and Viton. Seal kits are available for distribution to French and Francophone market customers requiring after-sales service capability. Contact CA-FIRE for complete maintenance kit specifications and pricing.

To receive an accurate quotation for DSP couplings, please provide the following when contacting CA-FIRE:

1. Coupling type — hose tail (DSPT/ART), female BSP thread (DSPF/ARF), male BSP thread (DSPM/ARM) or blank cap (DSPC/ARC).
2. Size — DSP40 (Ø 92 mm), DSP65 (Ø 116 mm) or AR100 (Ø 160 mm).
3. Hose tail bore — internal hose diameter in mm (for hose tail couplings).
4. Thread specification — BSP thread size (G1½", G2", G2½", G3", G4") for thread adaptors.
5. Seal material — NBR (standard) or Viton.
6. Quantity — pieces per SKU.
7. Special requirements — replacement seal kits, OEM packaging, French-language documentation.

Contact CA-FIRE at sales@ca-fire.com, via WhatsApp, or via the contact page. Response within 24 hours.