A powder coating shop is a listed stationary source
Under Annex No. 2 to Act No. 201/2012 Coll., on Air Protection, the application of powder plastics falls under code 9.11.
For this code, the Act sets no minimum capacity threshold for classification as a listed source. A powder coating shop may therefore fall under code 9.11 even with a relatively small annual consumption of powder coatings.
Before starting operation, the operator must hold a valid operating permit issued by the regional authority. Code 9.11 is also marked in column C of Annex No. 2, so operating rules are also part of the permit.
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| Area | Requirement for a powder coating shop |
|---|---|
| Source classification | Code 9.11 – Application of powder plastics |
| Operating permit | Yes |
| Operating rules | Yes |
| Dispersion study automatically under code 9.11 | No |
| Compensatory measures under code 9.11 | No |
| TOC emission limit under the Decree | At a designed consumption of powder plastics ≥ 10 t/year |
| One-off measurement | According to the emission limits and the conditions of the operating permit |
In permitting, the whole coating line must be assessed. Besides the booth itself, it may include surface pre-treatment, a drying oven, a curing oven, cooling, filtration equipment and possibly separate combustion sources.
What enters the air during powder coating
When powder coating is applied, emissions consist mainly of fine powder particles. The booth is therefore usually operated under negative pressure and the extracted air passes through a filtration system.
In modern systems, part of the powder that does not adhere can be captured and returned to the process. Residual particles must be captured by the final filtration.
Further emissions may arise during curing of the powder coating. During heating and curing, organic substances may be released from the powder coating, which for legislative purposes are expressed as total organic carbon – TOC.
Any gas heating of the oven, chemical surface pre-treatment, blasting, grinding or other process operations connected with coating must be assessed separately.
Emission limit at a consumption of 10 tonnes of powder plastics per year
Annex No. 5 to Decree No. 415/2012 Coll. sets the following specific emission limit for the application of powder plastics:
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| Total designed consumption of powder plastics | Pollutant | Emission limit |
|---|---|---|
| 10 t/year or more | TOC | 50 mg/m³ |
Under the Decree, the TOC emission limit applies to the curing and cooling of products.
The decisive factor is the total designed consumption, not the actual consumption in one particular year. If a line is designed, for example, for 15 tonnes of powder coatings per year, it cannot be assessed as below the limit in terms of the emission limit merely because it consumed 7 tonnes in the first year of production.
And what about TSP measurement?
In powder coating shops, the largest quantity of solid particles arises during the application of the powder itself. The question of measuring TSP – particulate matter is therefore very common in practice.
However, in point 4.4, Decree No. 415/2012 Coll. sets no separate specific TSP emission limit for code 9.11. It directly sets only a TOC limit of 50 mg/m³ at a designed consumption of powder plastics of 10 t/year and higher.
This does not mean, however, that dust emissions from the application booth do not need to be addressed.
If no specific emission limit is set for the source, the general emission limit may apply. Annex No. 9 to the Decree sets a general emission limit of 100 mg/m³ for TSP at a mass flow above 1,250 g/h.
In addition, the regional authority may set its own specific emission limit for TSP in the operating permit and at the same time determine the method and frequency of its verification. Under Section 4 of the Act, a specific emission limit is set in particular with regard to best available techniques and local conditions.
The decisive factor for a specific coating shop is therefore always the valid operating permit. It must make clear whether TSP is measured, at which stack, with what limit and at what interval.
How often emissions are measured
Decree No. 415/2012 Coll. classifies the activity of applying powder plastics under point 4.4 among sources for which the relevant one-off measurement is, as standard, carried out once every 3 calendar years.
When the source is first put into operation, the one-off measurement must be carried out no later than 4 months afterwards. The same four-month deadline also applies after a change of raw material or after an intervention in the design or equipment of the source that may lead to a change in emissions.
The specific scope of measurement must correspond to the operating permit. For a coating shop with a designed consumption above 10 t/year, the curing and cooling stack will be particularly important for the determination of TOC. If the permit sets a TSP limit for the extraction of the application booth, this stack is also measured.
When planning the measurement, the technology must be operated in a representative state and at an appropriate output.
Filtration of the application booth
The quality of filtration is a crucial operating parameter for a powder coating shop. Powder that is not captured on the product or in the recovery system must be captured before the extracted air is discharged.
Modern booths use, for example, cartridge or other high-efficiency filters. The design of the equipment differs significantly between manufacturers, so it is advisable to rely on the guaranteed parameters of the specific equipment.
When preparing documentation for the permit, we recommend knowing:
- the designed flow rate of extracted air, the type of filtration and the outlet dust concentration guaranteed by the manufacturer,
- the method of monitoring filter clogging, for example differential pressure, the regeneration method and the interval for their inspection or replacement,
- the handling of captured powder and the share of powder that is returned to the process.
These data are important for the expert report, the operating rules and, where applicable, for setting a control operating parameter.
Recirculation of filtered air
Some powder coating booths make it possible, after cleaning, to return part of the air to the production hall. From an energy perspective, such a solution may be advantageous, because the amount of heated air discharged from the building is reduced.
However, recirculation must also be assessed from the perspective of the work environment and employee exposure to dust. The requirements for the quality of workplace air are governed by other regulations than the emission limits for outdoor air.
The fact that filtration meets the conditions of the permit for the source of air pollution therefore does not automatically determine whether the air is suitable for return to the workplace.
Beware of the curing oven
The curing oven is an important part of a powder coating line. In it, the powder coating is heated to the prescribed temperature, melted and cured.
From the air protection perspective, it is necessary to distinguish between emissions arising from the curing powder and emissions arising from fuel combustion.
If the oven is heated by natural gas, the design of the system and the rated thermal input of the burners must be known. Depending on the technical solution, the combustion part may be a separate stationary source, which must be correctly classified in the permitting documentation.
The technical documentation must therefore state in particular the burner input, the heating method, fuel consumption, flue gas routing and the relationship between combustion and process stacks.
Pre-treatment may be a separate part of permitting
The quality of the powder coating depends on surface preparation. A plant may therefore include degreasing, phosphating, passivation, pickling, rinsing, blasting or other operations.
These technologies must be assessed separately. Depending on their capacity, the chemicals used and the technical solution, they may have their own emission requirements or may constitute another listed stationary source.
When reconstructing an old coating shop, a common mistake is to prepare the permit only for the new powder booth without reviewing the whole pre-treatment and curing section.
Operating rules are mandatory
Code 9.11 is marked in column C of Annex No. 2 to the Act. Operating rules are therefore a mandatory part of the operating permit of a powder coating shop.
The operating rules must correspond to the actual design of the technology. They should describe the process from the preparation of the product through the application of powder to curing, the emission abatement equipment, stacks, filtration checks, malfunction conditions and the responsibilities of operators.
The rules for operating the filtration equipment are particularly important. The document should determine how the operator recognises correct functioning of the filter, when regeneration or replacement of filter elements is carried out and how to proceed if they are damaged.
The operating rules are approved by the regional authority as part of the operating permit.
What must be correctly described in the permit
A well-prepared permit should make it possible to link the individual process parts unambiguously with the corresponding stacks.
Scroll the table horizontally to see all columns.
| Process part | Typical data for the permit |
|---|---|
| Powder coating booth | Capacity, powder consumption, extraction, filtration |
| Powder recovery | Method of capture and return of powder |
| Booth stack | Height, diameter, flow rate, TSP concentration |
| Curing oven | Temperature, capacity, operating time |
| Curing stack | Flow rate, TOC, method of emission discharge |
| Gas heating | Number of burners, thermal input, fuel |
| Cooling | Method of cooling and emission discharge |
| Pre-treatment | Chemicals used, baths, extraction |
| Measurement points | Accessibility and technical design for authorised measurement |
A uniform designation of stacks is very important. The same numbers should be used in the operating permit, the operating rules, the emission measurement report and the summary operating records in ISPOP.
Operating records and ISPOP
Because a powder coating shop is a listed source, the operator keeps operating records and submits the F_OVZ_SPE form annually via ISPOP.
The records track, for example, the annual consumption of powder plastics, the operating hours of the source, the quantity of emissions, data on the filtration equipment and the results of authorised measurements.
The summary operating records are reported by 31 March for the previous calendar year.
For a powder coating shop, it is advisable to also monitor over the long term the ratio between purchased powder, actual consumption, recovered material and filtration waste. These data help in checking the material balance and unusual changes in emissions.
The most common mistakes in permitting a powder coating shop
It is particularly problematic to adopt a general technical description from the supplier without the data needed for air protection.
The designed annual powder consumption, the guaranteed concentration downstream of the filter, the stack flow rate, the fan output or the parameters of the gas-fired curing oven may be missing.
Another common mistake is automatically mistaking a powder coating shop for a conventional paint shop using organic solvents. Powder coating has its own code 9.11 and its own rules.
Before the line is put into operation, it is therefore advisable to review the whole technological unit and its link to the existing permit of the plant.
What you can send us and what we will verify
For the assessment of a powder coating shop, you can send us:
- a technical description of the line, the designed consumption of powder coatings, and technical data sheets of the booth, filtration and curing oven,
- a diagram of extraction and stacks, air flow rates, guaranteed concentrations downstream of the filters, burner thermal input and information on surface pre-treatment,
- the existing operating permit, operating rules, expert report, emission measurement reports or the project documentation of the new line.
We will verify the classification of the individual parts of the technology and the requirements for the operating permit, operating rules, emission limits and TSP or TOC measurement. For a new or modified coating shop, we will prepare the necessary documentation and also point out the parameters that it is advisable to request from the technology supplier before installation.
You will find more information on the page Operating permit – NATURCHEM.
Related legislation
Act No. 201/2012 Coll., on Air Protection
Decree No. 415/2012 Coll., on the Permissible Level of Pollution and Its Determination