What this sector has to measure
Environmental monitoring instruments measure conditions that are reported to somebody else. That single fact reorganises the priorities: the method is usually fixed by a regulation, a permit or a standard, the calibration interval is prescribed rather than chosen, and the deliverable is a record that an authority or an auditor will accept rather than a reading that merely happens to be accurate.
The specification conversation therefore starts with the obligation. Which parameter, under which method, reported in which format and at what frequency - those answers determine the instrument class, the calibration arrangement and the data handling before any technical comparison is meaningful. An instrument that measures well but cannot produce an acceptable record does not satisfy the requirement, however capable it is.
The second theme is that environmental measurements are samples of a variable environment rather than readings of a controlled process. Air moves, water flows, noise reflects and weather changes, so siting and sampling strategy affect the result as much as the instrument does. Unlike a process measurement, there is frequently no later opportunity to correct the placement, which is why it belongs in the planning stage rather than in the installation.
Where the instruments sit
Ambient air quality
Site boundary and community monitoring of gases, particulate and dust. Instruments run continuously, and siting and exposure determine whether the record actually represents the area being reported on.
Stack and emission monitoring
Flue gas, particulate and flow measurement at the point of release. The method is normally prescribed, the sample has to be conditioned, and the record frequently forms part of a permit condition.
Water quality and discharge
Effluent, surface water, groundwater and process discharge. pH, conductivity, turbidity, dissolved oxygen and specific substances are measured, and continuous measurement is often required alongside periodic sampling.
Noise, meteorology and the site record
Boundary and workplace noise, wind and weather, and the general conditions around the site. These measurements often exist to explain or support the others, and they carry their own calibration requirements.
Instrumentation used in this sector
| Measurement | What is measured in this sector | Instruments commonly specified |
| Gas and vapour | Ambient and stack concentrations of carbon monoxide, carbon dioxide, nitrogen oxides, sulphur dioxide, volatile compounds and oxygen | Process and ambient analysers using electrochemical, infrared, photoionisation or optical methods, with sample conditioning designed for the dust, condensate and temperature present |
| Particulate and dust | Ambient particulate concentration, dust deposition, and particulate in a stack | Optical scattering and gravimetric samplers for ambient work, and optical or gravimetric measurement for emission monitoring, with the method fixed by the permit |
| Water quality | Effluent and surface water chemistry, including pH, conductivity, turbidity, dissolved oxygen and specific substances | In-line analysers and transmitters with sample conditioning, and comparable instruments at the sampling points where continuous measurement is required |
| Flow | Effluent discharge, surface water, and the flow in a stack or duct | Electromagnetic and ultrasonic meters for liquid, and differential-pressure or ultrasonic measurement for stack flow, where the velocity profile and the straight runs available dominate the result |
| Noise | Boundary, workplace and environmental noise | Integrating sound level meters with the correct weighting and time constant, plus an acoustic calibrator used before and after a measurement series |
| Meteorology and data handling | Wind speed and direction, temperature, humidity, rainfall, and the assembled site record | Weather station instruments alongside loggers and monitoring software that assemble the individual measurements into the record that has to be reported |
The applicable method, the calibration interval and the form of the record are normally prescribed before the instrument is chosen, and they should be stated in the enquiry.
How to specify for an environmental monitoring programme
- The obligation first: which parameter, under which regulation, permit or standard, reported to whom and how often. In this sector that answer shapes everything else.
- The prescribed method, because it fixes the technology, the calibration interval and frequently the data format, and an alternative method may not be acceptable however well it performs.
- Whether the measurement is continuous or periodic, since sampling strategy and continuous monitoring are different disciplines with different equipment and different records.
- The calibration arrangement: what reference material or service is needed, whether it is available locally, and who carries the calibration out.
- Siting and exposure, which cannot easily be corrected later and which determine whether the record represents the area being reported on.
- Data handling, including completeness, validation, storage and the format in which the record has to be produced.
- The power and communications available at the monitoring point, since remote locations frequently decide the configuration rather than the measurement.
- Whether the measurement supports a legal obligation or an internal management target, because the two justify different levels of rigour, documentation and equipment.
Standards and approvals that may apply
- The regulatory framework or permit that defines the parameters, the methods and the reporting frequency for the site.
- Emission and discharge limits, which determine the range and the resolution the measurement has to cover rather than a general preference.
- Ambient quality standards and monitoring methods, which govern the siting and the sampling arrangement as well as the instrument.
- Calibration and traceability requirements, including any accreditation the measurement or the supporting laboratory has to hold.
- We describe what an installation may have to meet. We do not claim that an approval is held for a product unless the certificate has been supplied to us, and the product pages follow the same rule.
Applications in this sector
