🌿 Dust in waste gases (low concentrations) — manual gravimetric method

Environment PN-EN 13284-1

Overview

EN 13284-1:2017 specifies the standard reference method (SRM) for the measurement of low concentrations of dust in ducted gases — below 50 mg/m³ under standard conditions (dry gas, 273.15 K, 101.3 kPa). It was developed and validated above all for gases from waste incineration plants (field tests with particular regard to concentrations of about 5 mg/m³), but it may be applied to other stationary sources and to higher concentrations; where the gases contain unstable, reactive or semi-volatile substances, the result depends on the conditions of sampling and of the treatment of the filter. The 2017 edition replaced EN 13284-1:2001; part 2 of the standard concerns the quality assurance of automated measuring systems for dust. In Poland the regulation of the Minister of Climate and Environment on the requirements for carrying out measurements of emissions indicates PN-EN 13284-1 (or PN-Z-04030-7) as the reference method for dust in the control of continuous measurements.

Valid results are obtained only where the gas stream at the place of measurement has a sufficiently settled velocity profile (EN 15259), where sampling is carried out without disturbing the stream, with a sharp-edged nozzle directed upstream under isokinetic conditions, where the samples are taken at a set number of points of the sampling plane (the distribution of the dust is not uniform), where the sampling system is leak-tight and designed so as to avoid condensation, chemical reactions and deposits in front of the filter, where the filtration is carried out at a suitable temperature (the temperature of the stack or the recommended at least 160 °C), where the deposits from in front of the filter are taken into account, where the value of the field blank does not exceed 10 % of the lowest emission limit value or 0.5 mg/m³ (whichever is the greater), and where the expanded uncertainty from the uncertainty budget does not exceed the requirements of the objective of the measurement — for regulatory purposes 20 % of the emission limit value.

Method principle

A stream of sample gas is taken from the main stream at representative measurement points over a measured time, with the stream controlled isokinetically (the velocity and the direction of the gas entering the nozzle equal to the velocity and the direction of the gas in the duct) and with a measured volume. The dust entrained with the gas is separated by a pre-weighed flat filter, which is then dried and weighed again; the deposits in front of the filter in the sampling system are also recovered (by rinsing) and weighed. The increase in the mass of the filter and the mass of the deposits from in front of the filter are attributed to the dust from the gas sampled, which makes it possible to calculate the concentration. Two configurations are permitted: in-stack filtration (the filter in a housing directly behind the nozzle; a very short section between the nozzle and the filter, the diameter of the filter usually up to 50 mm, a flow of about 1–3 m³/h; the temperature of filtration equal to the temperature of the gas, a risk of clogging where there are droplets) or out-stack filtration (a suction tube and a filter housing of controlled temperature, filters of 50–150 mm, a flow of 1–10 m³/h; obligatory where there are droplets in the gas). All the parts in contact with the gas — of stainless steel, titanium, quartz or glass, with smooth surfaces and a minimum number of joints.

Applications

• Periodic measurements of dust emissions from waste incineration and co-incineration plants and from large combustion plants
• Calibration and control (QAL2, AST in accordance with EN 14181) of automated measuring systems for dust — the reference method indicated in the regulation on measurements of emissions
• Measurements of dust emissions from industrial installations (cement works, steelworks, boiler houses) downstream of dust-removal equipment
• Parallel sampling of dust for the determination of metals (EN 14385) and mercury (EN 13211) in the same isokinetic system
• Checking of the effectiveness of fabric filters and electrostatic precipitators at low concentrations

Key parameters

Standard

Standard number

PN-EN 13284-1:2018-02 (EN 13284-1:2017)

Title (PL)

Emisja ze źródeł stacjonarnych — Oznaczanie stężenia masowego pyłu w zakresie niskich wartości — Część 1: Manualna metoda grawimetryczna

Title (EN)

Stationary source emissions — Determination of low range mass concentration of dust — Part 1: Manual gravimetric method

Step-by-step procedure

1. Planning

   Plan the measurement in accordance with EN 15259 (the measurement section and the sampling plane, the number and the position of the points of the grid, the sampling ports, the platform). Agree with the plant the objective, the dates, the duration and the operating conditions of the installation (a steady state maintained during the sampling). Calculate in advance the expected mass of dust, so that the blank is attainable and the filter is not overloaded (annex E). Choose in-stack or out-stack filtration (where there are droplets — out-stack).

2. Preparation of the filters and of the blank

   Condition the filters and weigh them with weighing control; prepare a field blank (the whole procedure without sampling the gas) — it must be taken in every campaign.

3. Preliminary measurements and leak test

   Measure the velocity, the temperature, the pressure and the composition of the gas (O₂, humidity) at the points of the grid, choose the nozzle for isokineticity; carry out a leak test of the system.

4. Sampling

   Sample isokinetically in turn at each measurement point (grid measurement), maintaining the temperature of filtration and recording the volume, the temperature and the pressure at the gas meter; for sampling of 30 min in large ducts use two systems at the same time.

5. Recovery of the deposits and weighing

   After sampling rinse the parts in front of the filter (the nozzle, the suction tube), evaporate the rinsings and weigh them; dry the filter and weigh it with the same weighing control procedure as before the sampling.

6. Calculations and test report

   Calculate the volume flow of the sampling and the concentration of dust from the sum of the mass on the filter and of the deposits from in front of the filter, convert it to standard conditions, dry gas and reference O₂; draw up an uncertainty budget (annex G) and a test report (clause 11), noting the lack of a suitable place of measurement or unstable operation of the installation.

Required equipment and apparatus

Health and safety (OHS)

• Work on the stack platform and at the sampling ports of hot gases — protection against falling, heat-resistant gloves
• The heated parts of the system (the filter housing ≥ 160 °C) may cause burns; insert and withdraw the probe wearing gloves
• Use the solvents for rinsing the deposits in a fume cupboard; treat filters with dust from incineration plants as potentially toxic

Frequently asked questions