GUIDE

From probe to emissions report

The complete CEMS chain: representative sampling, a line without losses or condensation, sample conditioning, analysers, flue-gas state measurements, DAHS, calibration gases, quality assurance and a secure archive.

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MEASUREMENT CHAIN

Eight links, one chain

80% of CEMS failures are the probe, the line and the sample filter, so the review starts at the source.

01Sampling probe
Installed in the duct at a point that meets the standard; with back-purge and a ceramic or SS filter at the inlet. Material SS316L, titanium for aggressive media; probe temperature up to 400 °C.
02Heated line
PTFE line heated to 120–180 °C, up to 100 m long. A line below dew point loses SO₂ and HCl; purging runs automatically on a timer and extends the service interval.
03Sample conditioning
Gas cooler (Peltier cooler-dryer) and a 2–5 µm sample filter in a conditioning cabinet with a chiller. A spare filter cuts downtime.
04Gas analysers
The method is chosen for the component and the range: NDIR for CO, CO₂, SO₂ and NOₓ; UV fluorescence for SO₂; chemiluminescence for NOₓ; FID for total organic carbon; paramagnetic or zirconia for O₂. The range is chosen from the actual figures, not "with margin".
05Flue-gas state and dust
Concentrations are referred to the same temperature, pressure, humidity and O₂, so the gas state is measured as well. The dust monitor (laser, triboelectric or optical with window purge) is fitted after the filter and before the ID fan: a jump in the reading means a torn bag.
06DAHS: data acquisition and transfer
PLC cabinet, operator panel, Modbus RTU/TCP and OPC UA, UPS and lightning protection. Reports are generated for 20 minutes, hour, day and month; the channel is Ecoonline.uz (Uzbekistan) or ASM (Kazakhstan).
07Calibration and quality assurance
A stock of calibration gases, auto-zero, zero/span checks and annual QAL2 / AST verification to EN 14181. Accuracy ±2% of full scale.
08Archive and reporting
Local archive of at least 3 years: without a stable link the data are not accepted, and the archive saves you when the link drops. The communication link is duplicated.

PARAMETERS

Key figures by link

Link

01 / 05Probe and line

Typical parameters: Probe up to 400 °C; line up to 100 m, heated to 120–180 °C; filter 2–5 µm; timed purge
What to check: Dew point, purge, spare filter, leak-tightness

Standards: USEPA 40 CFR 60/75, EN 14181, ISO 14956, QAL1/2/3. Under Oʻz MSt 195:2024 the measurement frequency is at least once per minute and the response time (T90) no more than 45 seconds.

WORTH KNOWING

Common mistakes

80% of CEMS failures are the probe, the line and the sample filter
A line below dew point loses SO₂ and HCl
The analyser range is chosen from actual figures, not "with margin"
A jump in the dust reading is the first sign of a torn bag
Without a stable link the data are not accepted; a local archive saves you when the link drops
The sampling point must meet the requirements of the standard
A CEMS does not replace cleaning; it only measures
The system does not run without regular calibration and span gases

AQMS

Without met data the result cannot be tied to a source

An AQMS monitors ambient air quality at the sanitary-zone boundary and in residential areas: PM10 / PM2.5 / TSP dust monitors, ground-level gas analysers (SO₂, NOₓ, CO, O₃) and a climate-controlled shelter. The data are accepted by the regulator and show the contribution of your site specifically; an AQMS works in tandem with the CEMS.

Weather station: ultrasonic wind sensors (0–60 m/s, ±0.3 m/s), temperature, humidity, pressure and precipitation sensors, a 2 or 10 m mast with lightning protection; the height is set by the method statement. Power from the mains with a UPS, solar panels optional; communications by GSM, fibre or radio link. Sensors are heated where icing occurs.

SERVICE