Reading a QAL1 certificate: does it actually cover TPM and opacity on your biomass boiler?

Every analyser we’d consider recommending carries a QAL1 certificate — proof it was tested to EN 15267 by an accredited body and found fit for some application. What a certificate doesn’t say, in bold letters on the front page, is whether that application is yours. Two systems can both be validly certified and still not be equally suited to a biomass boiler in Malaysia. The difference is in the detail most buyers never read past page one.

QAL1 certificates are public documents — every one referenced here is registered and searchable at qal1.de, published in the German Federal Gazette by the German Environment Agency (UBA). You don’t need to take a supplier’s word for what’s on one. Search the manufacturer and model you’re being quoted, open the certificate, and read it yourself.

Why a biomass boiler needs both, from one system

We’ve covered this in detail in CEMS for biomass boilers: once your measured dust load reaches 2.5 kg/hour, two provisions of the Clean Air Regulations 2014 converge on the same stack. The Second Schedule sets a Total Particulate Matter limit of 150 mg/m³ at 12% CO₂ for solid fuel and requires continuous monitoring at that threshold. Regulation 12(3) separately requires a transmissometer for opacity: any premises that emits 2.5 kg/hour of dust or more, or has the potential to emit smoke darker than Ringelmann Shade No. 2, must install and operate one. In practice, for most biomass boilers it’s the same 2.5 kg/hour figure that decides both obligations at once — one system needs to cover both.

That makes the certificate’s answer to a simple question decisive: does this analyser actually produce an opacity reading, or only a dust concentration?

Check 1 — what does it actually measure?

The DOE CEMS Guidelines (Version 8, 2025) list the recognised particulate-monitoring techniques and what each one can report (§3.1, Table 3.2). Two are relevant here, and they behave differently:

Optical extinction (transmissometer). A beam crosses the duct and the loss of light — the extinction — is measured directly. Because opacity is a measure of light loss across a path, this technique reports transmittance, opacity and dust concentration from the same measurement. The Guidelines note a typical usable range of roughly 10 to 2,000 mg/m³, and specifically flag that high-moisture flue gas can affect accuracy — adding, in the Guidelines’ own words, that “this type of emission typically occurs at biomass boiler which uses fuel with high moisture content.” Malaysia’s own regulator guidance names biomass boilers as the reason this matters.

Scattered light (backscatter). A beam is fired into the gas stream and the light reflected back toward the source is measured. The Guidelines describe this technique as giving “a measure of particulate concentration… after calibration with SRM,” reported to suit low particulate concentrations. It has no path across the duct to measure a transmittance loss over, so it has nothing to report as opacity — the certificate for a system built this way lists dust concentration only.

Before anything else, the certificate’s “measured values” or “certified components” section tells you which family you’re looking at. If opacity isn’t listed, it isn’t measured — no matter what else the datasheet promises.

Check 2 — what range is it certified to?

A QAL1 certificate doesn’t just say an analyser works. It states the specific range over which it was tested and found compliant, and that range has to sit sensibly against your Emission Limit Value — the same principle behind MS 2564’s rule that “the certification range is always related to the daily ELV,” which we cover in the QAL1 post. A certificate is not a blanket license to measure anything; it’s a statement about a tested window.

Transmittance-type certificates typically state their range in extinction units (Ext), not mg/m³ directly, because the mg/m³ equivalent depends on the actual measurement path length across your specific duct — that conversion is fixed on-site during QAL2, not printed once on the certificate. A reference conversion is usually given at one path length (for example, a stated range might read “0–0.1 Ext ≙ 15 mg/m³ dust at a 5 m measurement path”), alongside several wider certified ranges extending well beyond it.

Scattered-light-type certificates, by contrast, are usually stated directly in mg/m³ — no path-length conversion needed, but also no flexibility beyond the figure printed.

Two real certificates, read side by side

Both of the following are current, valid EN 15267 / QAL1 certificates for products actively sold into the Malaysian market. One is the SICK DustHunter T100 — the double-pass transmittance system we install on biomass boilers. The other is a competing product; we’ve left its name off, because the point of this exercise isn’t who makes it, it’s what its own certificate says.

Malaysia’s Second Schedule sets the biomass TPM limit at 150 mg/m³ — not 20, not 60.

The DustHunter T100’s ranges aren’t reducible to one number line the same way — extinction units need the installed path length to convert — but the widest of its five certified ranges extends ten times past its stated reference point, which comfortably brackets a 150 mg/m³ application in a way the competing system’s single 0–20 mg/m³ range does not.

What this means before you sign a quotation

Two checks, in this order:

1. Does the certificate list opacity, or only dust? If your boiler needs both under Regulation 12(3) and the Second Schedule, a dust-only certificate can’t be the whole answer — you’d need a second instrument, or a different analyser.
2. Does the certified range reach your ELV, with margin? Look up your own Second Schedule row — 150 mg/m³ for general solid fuel — and check it against the certificate’s stated range, not the sales brochure’s.

Both checks take five minutes. Before you sign anything, go to qal1.de, search the exact manufacturer and model on your quotation, and open the certificate yourself — don’t rely on a datasheet’s summary of what it says. We cover the physical side of a compliant installation — what’s actually mounted on the stack — in Anatomy of an in-situ CEMS install, and the broader extractive-vs-in-situ decision in how a CEMS actually measures.

Evaluating a quotation and want a second opinion on whether the certificate actually fits your boiler? Talk to us — we read these certificates against the DOE CEMS Guidelines we helped write, before anything gets installed.

This article is general guidance, not legal advice. Certificate details are drawn from currently valid, publicly registered EN 15267 / QAL1 certificates at qal1.de; verify the current status of any certificate directly before relying on it. For obligations specific to your facility, refer to the current Clean Air Regulations 2014, the DOE CEMS Guidelines, or speak with us directly.