How Boreal Laser Measures Gas Inside a Pipe, Stack, or Duct

Boreal Laser measures gas inside a pipe, stack, or duct by pairing a GasFinder3 Analyzer with a measurement head designed to sit in or on the process stream. For in-situ and extractive analysis, the company lists two heads for this job: the Stack/Duct (SDX) Probe, which makes a direct, non-contact measurement within a stack or duct for quantitative or feedback-control applications, and the Insertable (IPX) Probe. Both are part of the same GasFinder3 measurement-head family, so the analyzer does the laser measurement while the head defines how the light reaches the gas.

The measurement principle behind every head

All GasFinder instruments and measurement heads use Tunable Diode Laser Absorption Spectroscopy (TDLAS). A laser is tuned across an absorption feature of the target gas, and the amount of light absorbed over the path is used to determine gas concentration. Boreal Laser describes the result as a quantitative measurement of a specific target gas, and positions the technology for toxic, combustible, hazardous, and greenhouse gases in industrial hazardous-area applications.

The practical consequence for in-pipe work is that the measurement is optical: the gas is measured along the laser path rather than by pulling a sample to a remote sensor. That is why the SDX probe is described as direct and non-contact for the gas inside a stack or duct.

Stack/Duct (SDX) Probe: direct in-stack measurement

The SDX Probe is the head to choose when the gas of interest is flowing through a stack or duct and you want the measurement made in place. Combined with a GasFinder3 Analyzer, it creates a direct, non-contact measurement within the stack or duct, and Boreal Laser lists it for quantitative or feedback-control applications.

Two conditions follow from that description:

• Quantitative use means the reading is intended to represent concentration, not just a yes/no alarm. If you need a number for reporting or process decisions, this is the stated use case.
• Feedback control means the measurement can feed a control loop. Before committing, confirm with your regional distributor that the response time and interface of the configured analyzer/head pair match your control system's requirements, since the source material does not publish those figures.

Because the probe measures across the stack or duct, the installation geometry matters: the laser path must cross the gas you want to measure. Ask your distributor to confirm the path arrangement for your duct size and access points.

Insertable (IPX) Probe: in-situ and extractive analysis

The IPX Probe is listed under the same in-situ and extractive analysis category. The source describes it as an insertable probe combined with a GasFinder3 Analyzer, but does not spell out its optical path or its exact split between in-situ and extractive use. Treat the following as the decision framework rather than a specification:

If your priority is a cross-stack quantitative reading for control, the SDX is the clearly documented option. If your priority is inserting a probe into a pipe or vessel, the IPX is the head Boreal Laser lists for that role, but you should get the path length, mounting, and sample-handling details from the distributor before specifying it.

What to confirm before you specify

The source material establishes the architecture (GasFinder3 Analyzer plus a measurement head) and the intended applications, but not the numbers. Before ordering, ask a regional distributor — Boreal Laser states its products are sold, commissioned, and supported by regionally focused technical sales organizations — for:

1. The detectable gases for your target molecule, using the company's products-by-gas listing.
2. Path length and mounting requirements for your pipe, stack, or duct dimensions.
3. Whether the IPX configuration is in-situ or extractive for your process, and what that means for sample conditioning.
4. Outputs and response behavior if the reading will drive feedback control.
5. Hazardous-area certification for your installation zone, since the company positions these instruments for industrial hazardous-area applications.

Why this architecture suits difficult in-pipe applications

Boreal Laser attributes its adoption in 48 countries to quantitative performance in difficult applications, a fail-safe design, and maintenance-friendly operation. For in-pipe work, the relevant mechanism is that an optical, non-contact measurement inside a stack or duct avoids routing the gas to a separate analyzer location. The trade-off is that the optical path must be engineered for the specific stack or duct, which is why the head selection and site survey come before the analyzer configuration.

For a concrete case: a plant that wants a continuous concentration reading from a duct to trim a process setpoint would pair a GasFinder3 Analyzer with an SDX Probe and confirm the control interface with the distributor. A plant that needs to insert a probe directly into a pipe for analysis would start from the IPX Probe and settle the in-situ versus extractive detail with the distributor.