Two smoke methods dominate outside the NBS chamber. For cables, IEC 61034 burns a cable sample in a 3-metre cube and measures how much light the smoke obscures horizontally across the cube - the figure that low-smoke cable specifications are written around. For building materials, ASTM D2843 measures smoke density in a dedicated chamber as a percentage obscuration. Motis supplies both configurations: the 3MC three-metre cube and the XP-2 for ASTM D2843.
How the Smoke Density Tester (3-Metre Cube & ASTM D2843) works
In the 3-metre cube, the cable specimen is laid horizontally above an alcohol fire tray inside the cube. A light source and photocell face each other across the cube at the standard height, and the software records the fall in light transmission as smoke builds, reporting the minimum transmission reached. In the D2843 chamber, the specimen burns in the chamber and smoke density is derived from light absorption along the measurement path.
Key specifications
| Cable method | IEC 61034 (3-metre cube); BS 6853 also listed for this configuration |
|---|---|
| Building material method | ASTM D2843 (XP-2) |
| Principle | Light transmission / attenuation through accumulated smoke in a defined volume |
| Reported values | Minimum light transmission (IEC 61034); smoke density rating as percentage obscuration (ASTM D2843) |
What the test reports
- Minimum light transmittance during the test (cables)
- Smoke density value and curve (building materials)
- Time-resolved obscuration record for both methods
Applications
Cable manufacturers demonstrating low-smoke performance for CPR and specification work, and building product laboratories working to US methods, are the main users. For chamber-based specific optical density to ASTM E662 or ISO 5659-2, see the NBS smoke density chamber.
Frequently asked questions
Which standard should I order against?
Order against the standard your reports must cite. The instrument platform is shared across the listed standards, but fixtures, software templates and calibration routines differ, so name the standard (and its year) in your inquiry and the configuration will be matched to it.
Which smoke test do my customers ask for?
Cable buyers usually name IEC 61034 transmission values; aviation and rail buyers name ASTM E662 or ISO 5659-2 optical density, which is the NBS chamber; US building work may name ASTM D2843. Match the instrument to the method in your specification, and tell us the method in your inquiry.
Can one laboratory run both cable and material tests?
Yes; the two configurations are separate instruments with different volumes, and many laboratories run the cube for cables and the NBS chamber for materials. We can quote them as a package.
Configuration, installation and support
Every Smoke Density Tester (3-Metre Cube & ASTM D2843) is supplied as a configured system, not a bare instrument: the test chamber or frame, the burner or heater assemblies named in the method, the measurement chain and the control software with the report templates for IEC 61034, ASTM D2843. Before quotation we confirm the installation conditions with you - floor loading and ceiling height for large rigs, exhaust and extraction routes, gas and fuel services, and power supply - because a fire test instrument only produces defensible data when the room around it is right. Commissioning covers assembly, calibration of the measurement chain against the method's own checks, and training of your operators on running the test and maintaining the apparatus. Spare ignition parts, thermocouples and other consumables for the first period of operation can be included in the supply, and the instrument is supported with calibration and maintenance services after installation.
What to include in your inquiry
To quote the Smoke Density Tester (3-Metre Cube & ASTM D2843) correctly the first time, send: the standard and edition you will test to (IEC 61034, ASTM D2843); the materials or products you will test and their sizes; the configuration options you already know you need; and the destination laboratory's location and available services. If you are building a new fire laboratory rather than adding one instrument, say so - this apparatus is often planned together with the other instruments in its category, and a combined layout and exhaust plan is cheaper than three separate ones.