Inline Water Flow Indicator DN25
Threaded Paddle Flow Switch · DN25 / 1 inch · NPT / BSP / BSPT · 1.6 MPa · IP65
Inline Water Flow Indicator DN25 — Threaded Paddle Type
The CA-FIRE DN25 inline water flow indicator is the dedicated small-pipe variant of our paddle-vane flow detector family. Instead of clamping onto the outside of the pipe with a saddle, the unit threads directly into the pipe run at both ends — making it the only correct choice for 1-inch / DN25 sprinkler branches where saddle-mount units cannot fit. Supplied with NPT, BSP or BSPT thread options to match your regional installation standard.
What Is an Inline Water Flow Indicator?
An inline water flow indicator — also searched as "in line water flow indicator" or "threaded paddle flow switch" — is a flow detector that installs directly in the pipe run with threaded connections at both ends. Water must pass through the body of the indicator, where a paddle vane sits permanently in the flow path and actuates a micro-switch when water begins to move.
This format is different from the more common saddle-mount style, which clamps onto the outside of the pipe. Inline units are used on small-diameter sprinkler branches (typically DN25 / 1 inch) where saddle-mount units would be physically too large to fit. The electrical output, alarm flow behaviour and FACP connection are the same as any paddle-type flow indicator.
Inline DN25 or Saddle-Mount? Choose by Pipe Size
The choice between inline DN25 and saddle-mount ZSJZ is not a performance trade-off — it is determined entirely by the diameter of the pipe you are installing on. Use the guide below to specify correctly the first time.
- Single-zone residential sprinkler systems
- Small office or hotel-room branch lines
- Light-hazard retail fit-outs (cafes, boutiques)
- Retrofit zones with small-bore pipe only
- Secondary branches feeding 2-6 sprinkler heads
- Any pipe where a saddle U-bolt physically will not fit
- Main sprinkler risers (DN50 to DN300)
- Branch mains in commercial buildings
- Floor-level zone indicators in high-rises
- Warehouse and factory sprinkler branches
- Any pipe run where saddle mounting avoids pipe cutting
- Retrofit projects where pipe must stay pressurised
Inline DN25 Design Features
Specify Your Thread Standard
Three thread options cover every international sprinkler code. The thread type is machined at the factory and cannot be field-converted, so confirm at order stage based on your project specification.
Full Technical Specifications
Single-size unit — one spec table covers everything. Wiring, signal output and FACP behaviour are identical to the ZSJZ saddle-mount family, so installations mixing saddle and inline units can use common electrical drawings.
| Parameter | Specification |
|---|---|
| Model | ZSJZ-DN25 (inline threaded) |
| Nominal size | DN25 / 1 inch |
| End connection | Female threaded, both ends |
| Thread options | NPT · BSPT · BSP (specify on order) |
| Body material | Brass (standard) or nickel-plated steel (optional) |
| Paddle material | Stainless steel flexible vane |
| Gasket / seal | EPDM rubber O-ring |
| Working pressure | 1.6 MPa (16 bar / ~230 psi) maximum |
| Alarm flow rate | 15 L/min (equivalent to one open sprinkler head) |
| Media temperature | 4°C to 70°C |
| Ambient temperature | −10°C to +55°C |
| Switch type | Hall-effect micro-switch, sealed |
| Contact form | Two sets of normally closed (NC) contacts |
| Contact rating | DC24V 1A / AC220V 0.5A |
| Enclosure rating | IP65 |
| Cable entry | M16 × 1.5 threaded cable gland |
| Retard delay | Factory-set, ~20 seconds |
| Mounting orientation | Horizontal or vertical (flow arrow must match direction) |
| Standards | Manufactured to GB 16280; compatible with NFPA 13, UAE Civil Defence, SASO, SIRIM, SABS installation practice |
Where DN25 Inline Flow Indicators Are Used
Factory-Direct Export Terms
The DN25 inline unit has the lowest MOQ floor and fastest lead time in the CA-FIRE water flow indicator range. Bulk pricing tiers kick in at 500 pieces and again at 2,000 pieces — ideal for residential estate developments and multi-tower hospitality projects.
