Gas analyser, smoke meter or combined unit?

gamme complète d'équipements de mesure des émissions CAPELEC

Three devices, three different measurements

A gas analyser and a smoke meter are not two variants of the same device: they measure distinct parameters on distinct engine types. The combined unit, for its part, is not a third measurement but a combination of the two in a single unit.

The exhaust gas analyser measures the composition of the gases emitted by a spark-ignition engine: it is designed for petrol engines, including LPG and CNG depending on the device.
The smoke meter measures the opacity of the smoke emitted by a diesel engine, i.e. the attenuation of a light beam passing through the exhaust gases.
The combined exhaust analyser combines these two functions into a single unit, with a common interface.

In other words: the question is never ‘analyser or smoke meter?’ but ‘what types of engines does my business deal with, and how should the workstation processing them be organised?’

Matching engine types to the necessary equipment

The configuration is determined by the actual composition of the vehicle fleet you are managing, both now and in the medium term.

Activity	Measurement requirement	Configuration to be considered
Fleet mainly petrol	Exhaust gas composition.	Gas analyser.
Fleet consisting mainly of diesel vehicles	Smoke opacity, and, depending on the market, particle count.	Smoke meter, possibly supplemented by a particle counter.
Mixed fleet	Both measurements, at the same test station.	Combined unit, or separate devices if the organisation’s requirements justify it.
Mixed fleet with high throughput	Both measurements, with a fixed turnaround time.	Combined unit integrated into the data-entry station, to minimise handling.

Less common engine types deserve attention: equipping a centre solely for the majority of the fleet leads to vehicles being turned away or the need to improvise a measurement station a few months later.

Separate or combined units?

Where both measurements are required, both approaches are valid. The choice between them depends more on the layout of the workstation than on the measurement itself.

	Separate devices	Combined
Workstation footprint	Two units to be positioned and supplied with power.	A single unit, reduced footprint.
Work organisation	Two interfaces, two procedures for the operator.	A single interface, standardised procedures.
Flexibility	Each unit can be moved or replaced independently.	The entire system is upgraded as a single unit.
Availability	A fault only affects one measurement.	A system outage affects both measurements.
Scalability	A unit can be added later, depending on available space.	To be sized from the outset, depending on the model’s functions.

The exact functions and measurements covered vary by model: see the ranges of gas analysers, smoke meters and combined exhaust analysers.

Capelec’s emissions control ranges

Each range is available as a gas analyser, a smoke meter or a combined unit: first choose the measurement, then the working environment.

Range	Principle	Versions	Who it’s for
CAP3201 Series	Standalone unit, LCD screen and built-in printer	CAP3201 G (gas), CAP3201 O (smoke meter), CAP3201 GO (combined)	Vehicle inspection and workshops
CAP3500 series	Mobile, tablet-controlled on a compact trolley	CAP3500 G (gas), CAP3550 O (portable smoke meter), CAP3500 GO Workshop (workshop combination unit)	Workshops, MRA and pre-inspection
CAP3600 series	PC-based, 23–27″ touchscreen kiosk, encrypted data transmission	CAP3600 G, CAP3600 O, CAP3600 GO, CAP3600 GO Workshop	Light commercial vehicles, lorries and 2-, 3- and 4-wheeled vehicles, workshops, production sites

For particle count measurement, see the CAP3070 particle counter.

Organisation of the workstation and interfaces

An emissions testing station is not just a piece of equipment: it is a workstation. Points to consider regarding its layout:

Access to the exhaust pipe depending on the vehicles being tested — position, height, accessibility from the workstation.
Ventilation or extraction of exhaust gases in the room.
The connection to the data-entry workstation, to avoid having to re-enter results manually.
The storage of probes and hoses, which affects their service life.

Maintenance and running costs

In addition to the initial investment, these devices require regular maintenance, which adds to the running costs:

The periodic checks specific to each type of measurement.
Consumables and wear parts: filters, probes, hoses, depending on the model.
Software updates in line with protocol changes.

These details are specified for the chosen configuration. See contract subscription and repairs.

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Can a smoke meter replace a gas analyser?

No. The two devices measure different parameters on different types of engines. They are complementary, but never interchangeable.

Is a particle counter also required?

This depends on the requirements applicable in your market and the types of engines you deal with. Particulate number measurement is not a substitute for opacity measurement: see our guide smoke meter and particle counter.

Is a combined unit slower than a dedicated device?

The measurement time depends on the model and the procedure, not on the principle of the combined unit. In practice, the time saved by using a combined unit stems mainly from the single interface and the elimination of the need to switch between workstations.

How can these devices be integrated into an existing system?

The available interfaces depend on the models and your installation. This aspect forms part of the assessment, particularly when replacing a device on a line that is currently in operation.