Component line 05 / Aspirating smoke detection
Very early warning aspirating smoke detection: detectors, sampling pipe and passive accessories
Host detector units with multiple pipe runs, 25 mm sampling pipe and fittings, capillaries, in-line filters and the passive accessories that make a network work. Referenced to UL 268 and to the EN 54-20 classes. Supplied as components. The pipe network calculation and the class assignment belong to your designer of record.
Standard references only. The EN 54-20 class a network achieves is evidenced by the manufacturer's test report for that network, not by the detector alone.
The unit of measurement is per metre of the smoke path, which is why an aspirating system can be quoted far more sensitively than a point detector and still be honest about it.
Why a data hall needs to sample air rather than watch the ceiling
A point detector waits for smoke to reach it. In a data hall the cooling load keeps air moving, the smoke is diluted long before it arrives, and a ceiling detector can sit under a layer of clean air while a cable smoulders in a tray two metres away.
An aspirating system reverses the arrangement. A small pump in the detector pulls air from a network of sampling holes drilled along a pipe, so the detector goes to the air instead of waiting for the air to come to it. The same pipe can sample the ceiling void, the raised floor void and the return air grille, which is where the smoke actually travels in a hall with a hot aisle and a cold aisle.
Engineering note · transport time is a calculation
Air takes time to travel down a sampling pipe, and the more holes there are, the less air each hole contributes. Hole size, hole spacing, pipe length, the number of bends and the pump capacity all interact, and the result is the transport time from each sampling point to the detector. That calculation is the designer's work. It is also the reason a pipe network copied from another project usually underperforms, even when every component is identical.
01 / Specification
Datasheets
| Pipe runs | 1 to 4, model dependent |
|---|---|
| Detection principle | Laser light scattering, particle counting on higher models |
| Sensitivity | Adjustable, quoted in % obs/m |
| Sensitivity class | EN 54-20 class A, B or C, per the network test report |
| Alarm levels | Three or four, with day and night sensitivity settings |
| Airflow monitoring | Per pipe, with a flow fault output |
| Filter | Replaceable inlet filter, field serviceable |
| Outputs | Relay per alarm level, fault relay, 4 to 20 mA or Modbus |
| Supply | 24 V d.c., or mains with a local supply |
| Enclosure | IP54, wall or rack mount |
| Pipe outside diameter | 25 mm ≡ ¾″ |
|---|---|
| Material | ABS as standard, metal for high temperature or return air locations |
| Fittings | Elbows, tees, unions, reducers, end caps |
| Sampling holes | Drilled to the network calculation, typically 2 to 5 mm |
| Support | Clips at intervals stated in the installation instructions |
| Fixing method | Solvent weld, or push fit with unions for serviceability |
| Sampling point holder | Capillary type, for points away from the pipe run |
|---|---|
| Capillary tube | Supplied to length, with the holder and the label |
| In-line filter | For dusty or contaminated locations |
| Dust filter | At the detector inlet, replaceable |
| Exhaust deflector | Returns exhaust air to the protected space |
| Silencer | Reduces pump noise where the detector is in an occupied room |
| Drilling jig | Sets hole size and spacing from the calculation |
| Labels and brackets | Pipe identification and pipe clips |
| Sampling location | What it catches |
|---|---|
| Return air grille | The whole room, because all room air passes through it |
| Ceiling void | Cable and containment faults above the hall |
| Raised floor void | Power and data cabling under the floor |
| Room air | Local sources that never reach the return path |
| In-rack | The cabinet itself, where airflow is highest and dilution greatest |
Exhaust and pressure
Where the detector sits inside the protected space, the exhaust has to return to the same space. Discharging a detector's exhaust out of a sealed room slowly depressurises it and changes how the sampling holes behave, which shows up as a flow fault months later rather than as an obvious installation error.
02 / Model list
Model designations
Add what you need and the list is carried into the enquiry form. Give us the number of sampling zones and the approximate pipe length per zone and the detector can be sized against them.
| Model designation | Item | Detail | Notes | Add to model list |
|---|---|---|---|---|
| EMS-AS-HOST-1P | Detector unit | Single pipe run | Wall mount, IP54 | |
| EMS-AS-HOST-4P | Detector unit | Four pipe runs | Independent airflow monitoring per pipe | |
| EMS-AS-PIPE-25 | Sampling pipe | 25 mm OD, ABS | Supplied in 3 m lengths | |
| EMS-AS-FIT-KIT | Fitting kit | Elbows, tees, unions, reducers, end caps | One kit per pipe run | |
| EMS-AS-CAP-3 | Sampling point assembly | Capillary with holder and label | 3 m capillary as standard | |
| EMS-AS-FILT-IN | In-line filter | For dusty locations | Replaceable element | |
| EMS-AS-FILT-DUST | Detector inlet filter | Service item | Order with the detector | |
| EMS-AS-EXH-DEF | Exhaust deflector | Returns exhaust to the protected space | For in-room detectors | |
| EMS-AS-SIL-01 | Silencer | Pump noise reduction | For occupied rooms | |
| EMS-AS-JIG-01 | Hole drilling jig | Sets hole size and spacing | One per site |
03 / Scope
What this line ships, and what it does not
Ships from us detection components
- Detector units with one to four pipe runs, with airflow monitoring
- Sampling pipe, fittings, end caps and pipe clips
- Capillary sampling point assemblies with holders and labels
- In-line filters, inlet dust filters, exhaust deflectors and silencers
- Drilling jigs, service spares and replacement filters
- Datasheets, model list and the listing certificate with its document number
Not from us by others
- The pipe network design, hole sizing and hole spacing
- The transport time calculation and the sensitivity at each sampling point
- The EN 54-20 class assignment, which follows from that calculation
- Installation, pipe fixing, hole drilling and pipe labelling
- Configuration, alarm level setting and panel integration
- Commissioning and the acceptance test
04 / On site
Getting the network right
- Sample where the air goes, not where the ceiling is. In a hall with a raised floor and a hot aisle, the return path carries the whole room past one place. A sampling point there sees everything the room produces, which no ceiling grid of point detectors can match.
- Every hole costs the others air. Adding sampling holes to an existing run without recalculating reduces the flow at every other hole. This is the single most common reason an aspirating installation fails a sensitivity test after a late design change.
- Class is a property of the network. The EN 54-20 class is demonstrated for a specific pipe network, not for a detector in isolation. A detector capable of class A sensitivity on one run is not class A on any network someone draws later.
- Filters are service items. An in-line filter that is never changed raises the transport time and eventually produces a flow fault. Stock the elements with the detector, not after the fault.
- Exhaust goes back where it came from. Recirculating the exhaust inside the protected space keeps the room pressure where the design assumed it was.
Engineering note · aspirating and point detection together
Aspirating detection is usually the early warning layer, not the only layer. Where a project needs point detection for a specific code path, or heat detection in a plant area, those devices remain. Nothing on this page replaces a requirement that a standard places elsewhere.
05 / Questions
Aspirating detection, asked and answered
Why aspirating smoke detection in a data hall instead of point detectors?
High airflow dilutes smoke before it reaches a ceiling mounted point detector, and the cooling load keeps the air moving. An aspirating system draws air from many small sampling holes in the ceiling void, the floor void and at return air grilles, so it sees a diluted sample that a point detector would miss.
Do you calculate the pipe network?
No. We supply the pipe, the fittings and the detector. The pipe network, the sampling hole sizes and the transport time calculation belong to the designer of record, and the assigned EN 54-20 class is evidenced by the manufacturer's test report for that network.
What do the EN 54-20 classes A, B and C mean?
They are three sensitivity classes for aspirating smoke detection devices defined by the European standard. Class A is the most sensitive and is the class normally referenced where very early warning is the objective, particularly in spaces with high air movement. The exact sensitivity band for each class is set out in the standard, and the class an installation achieves is demonstrated by the test report for the actual pipe network.
Can we add sampling points after the network is installed?
Physically yes, but it changes the network. Every additional hole takes a share of the airflow, so the sensitivity at the other points falls and the transport time rises. Any change to a network should go back through the same calculation that produced it.
Do you supply the detector with a class A certificate?
We supply the detector and its own listing documents, with the document numbers attached. The EN 54-20 class claim belongs to a network and is made in the manufacturer's test report for that configuration. Any supplier offering a class A certificate for a detector on its own is describing something the standard does not provide.
Aspirating smoke detection
Send the zones and the pipe lengths
Tell us how many sampling zones, the approximate pipe length in each and whether the detector sits inside the protected space. The quotation comes back with the detector, the pipe and the accessory list.
- Pipe
- 25 mm OD ≡ ¾″, ABS
- Runs per detector
- 1 to 4
- Reference
- UL 268, EN 54-20
- Scope
- Components only. Network design by others.