🌿 Dust in waste gases — measurement of concentration and mass flow rate by the gravimetric method (PN-Z-04030-7)

Environment PN-Z-04030-7

Overview

SCOPE FROM THE PKN CATALOGUE CARD, QUOTED VERBATIM (our translation): "The standard concerns manual measurements in the range of dust concentrations in waste gases from 0.001 to 100 g/cubic m. The method may be used for the calibration of automatic measurements. Requirements are given for three types of measurements: accurate, technical and indicative. The Annexes and Additional information give guidelines for determining auxiliary quantities and for assessing errors. Auxiliary tables and diagrams of typical measuring systems are included".

THE MOST COMMON MISTAKE: THIS IS NOT A STANDARD ON DUST AT THE WORKPLACE. The PN-Z-04030 series covers several sheets with very different subjects. Sheets 05 and 06 concern the determination of total and respirable dust at workplaces by the filtration-weighing method — and it is they that are cited in workplace environment testing. Sheet 7 concerns something else: dust in WASTE GASES, i.e. emission from a stationary source. Confusing these sheets is easy, because the series number and the first elements of the title are common, and the difference begins only in the third element. A laboratory that enters "PN-Z-04030-7" for testing air at a workplace cites a document outside the scope.

THREE TYPES OF MEASUREMENT — AND THIS IS THE ESSENCE OF THIS STANDARD. The card lists requirements for accurate, technical and indicative measurements. These are not synonyms or degrees of care of the person performing them: they are three different sets of requirements, on which depends how many measurement axes and points must be covered and what uncertainty the result carries. Citing the standard number alone without indicating the type of measurement does not yet say what was actually done.

REQUIREMENTS FOR THE MEASUREMENT SITE. In Poland the standard is the basic document deciding where a measurement cross-section may be located in a duct. A trade study devoted to measurement sites lists that the standard specifies: the location of the measurement cross-section, the conditions required for chimney flues discharging to the atmosphere, the rules for selecting the measurement cross-section when meeting these conditions is impossible, and the minimum number of measurement axes — and on that depends the number of sampling ports that must be made in the duct. The latter has direct investment consequences: ports are drilled in an existing stack and cannot be "added" during the measurement.

RELATIONSHIP WITH THE EUROPEAN METHOD. For low dust concentrations PN-EN 13284-1 applies — the European reference method for concentrations below 50 mg/m³, described separately in this database. The Polish regulation on emission measurements permits PN-EN 13284-1 or PN-Z-04030-7 for checking continuous measurements, which means that both documents live in parallel, each in its own concentration range: the national standard starts from 0.001 g/m³, i.e. from 1 mg/m³, and reaches 100 g/m³, so it also covers concentrations much higher than the range of the European method.

CALIBRATION OF AUTOMATIC MEASUREMENTS. The scope explicitly permits the use of this method for the calibration of automatic measurements. For a plant with an installed continuous dust monitor this means that the manual gravimetric measurement is the reference method against which the readings of the instrument are checked — not a test competing with it.

WHAT WE DO NOT GIVE. We do not have the text of the standard — PKN makes it available for a fee (36 pages, KT 280 Air Quality, ICS 13.040.40, publication date 30-12-1994). Therefore WE DO NOT GIVE: specific distances of the measurement cross-section from flow disturbances, the minimum number of axes and points for the individual types of measurement, the dimensions of the ports, formulas for the mass flow rate or limit values of errors. All these numbers are the content of the standard and its annexes.

Method principle

A probe ending in a nozzle is inserted through a port in the duct wall and a stream of gas is drawn through a filter element on which the dust is retained. The condition for correctness is isokinetic sampling: the velocity of the gas entering the nozzle must correspond to the velocity of the gas in the duct at that point, otherwise the stream separates on particles of different inertia and the sample ceases to be representative. The mass of dust is determined by weighing the filter element before and after the measurement, and the concentration — by relating this mass to the volume of gas passed, converted to reference conditions. The dust mass flow rate is calculated from the concentration and the volumetric flow rate of the gases in the duct. The standard divides measurements into accurate, technical and indicative, setting different requirements for each of them; it also contains auxiliary tables and diagrams of typical measuring systems.

Applications

• Measurements of dust emission from stationary sources — boiler houses, heating plants, industrial installations
• Calibration and checking of automatic dust monitors installed on flue gas ducts
• Assessment of the effectiveness of dedusting equipment — measurement upstream and downstream of the equipment
• Design of measurement sites: choice of cross-section, number of axes, number and location of ports
• Measurements at concentrations higher than the range of PN-EN 13284-1 (the national standard reaches 100 g/m³)

Key parameters

Standard

Standard number

PN-Z-04030-7:1994

Title (PL)

Ochrona czystości powietrza -- Badania zawartości pyłu -- Pomiar stężenia i strumienia masy pyłu w gazach odlotowych metodą grawimetryczną

Title (EN)

Air purity protection — Tests for dust content — Measurement of dust concentration and mass flow rate in waste gases by the gravimetric method

Step-by-step procedure

1. Establishing the type of measurement

   Accurate, technical or indicative — further requirements depend on this. The type is recorded in the report.

2. Selection of the measurement cross-section

   In accordance with the requirements of the standard regarding the location of the cross-section; when they cannot be met, the standard gives rules for the substitute procedure.

3. Preparation of the filter element

   Drying and weighing before the measurement.

4. Measurement of gas parameters

   Velocity, temperature, pressure and humidity in the cross-section — data for selecting the nozzle and for calculations.

5. Isokinetic sampling

   Suction through the nozzle at a velocity corresponding to the velocity of the gas at the sampling point, at points distributed along the measurement axes.

6. Weighing and calculation

   Re-weighing of the filter element, calculation of the concentration at reference conditions and of the dust mass flow rate. WE DO NOT GIVE THE FORMULAS AND LIMIT VALUES — they are in the content of the standard.

7. Report

   Full designation of the standard with the year, type of measurement, location of the cross-section, number of axes and points, conditions in the duct.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The measurement is carried out on an operating flue gas duct — hot gases, risk of burns, work often at height at the stack
• Waste gases contain carbon monoxide and other toxic substances — monitoring of the atmosphere and protection of the team are required
• Opening a port on a duct under overpressure causes an ejection of hot gas and dust
• SUBSTANTIVE NOTE: citing this standard for testing dust at a workplace is citing a document outside the scope — sheets 05 and 06 of the PN-Z-04030 series are appropriate there

Frequently asked questions