Aerox test centers for odour nuisance

AEROX® procedure to collect a proper odour sample

Rev. 030109

This handout describes procedures for performing odour measurements according to the Aerox standards. To determine an abatement efficiency, the guidelines in Sections 2, 3 and 4 below should be followed.

1. Indicative test with a small panel

In order to determine the difference in odour emissions between a treated sample and an untreated sample the following indicative test can be performed.

During a pilot test, treated and untreated samples can be collected from the pilot system using Nalophan sample bags. The best method is to collect both samples behind the Aerox-Injector, just before the fan. A sample barrel may be used to collect the samples.
By switching the Aerox -Injector pilot system on and off, treated and untreated samples can be obtained. These samples can be collected without pre-dilution and within a short period of time.
The samples can be smelled by a small panel, for instance 2 to 4 non-qualified persons, to determine whether there is any difference in odour sensation between treated and untreated air.

NOTE: It is not possible to determine an abatement efficiency using this qualitative test.

2. Guidelines for collecting an odour sample for olfactometric analyses

To collect a sample for proper olfactometric analysis, please adhere to the following guidelines:

All pieces of equipment that the sample comes into contact with should be made from Teflon, stainless steel, glass, Tedlar or Nalophan plastic. All other materials add odour to the sample.
For each sample a new filter should be used in the sampling equipment to exclude dust and fibres. It is preferable not to use a flat filter in order to avoid a layer of odorous dust on the filter.
Each sample should be diluted with enough odour free nitrogen to prevent condensation in the sample bag. Odour free nitrogen is obtained by using an active carbon filter and an absolute dust filter. During sampling an amount of nitrogen is mixed with the sampled air stream, and this should be done dynamically. The exact dilution factor should be measured for each sample. Dilution ratios of up to 10 times can be checked by measuring the oxygen concentration in a diluted sample compared to an undiluted sample. It is necessary to measure the oxygen concentration to a precision of 0.1% or better to do this. When larger dilutions are used the dilution system should be calibrated at site by measuring the pressures of the sampled air stream and the diluted air stream.
For each sample a new sample bag must be used.
Clean tubing should be used between the sampling port and sample bag for each sample.
Treated and untreated samples should be collected simultaneously in order to prevent influences from process fluctuations.
Before taking the sample the sample bags have to be pre conditioned. This can be achieved by flushing the sample bags for a short period.
The sample should be collected for at least 30 minutes in order to average influences from short term process fluctuations. A longer sample collection time will give a more representative average.
The sample should be collected using the "reversed lung" principle (up to 5 times dilution), or by means of the Venturi principle. These techniques ensure odorous air will not be cross-contaminated (by a pump, for example) during sampling.
Samples should be large enough for all necessary analyses in the laboratory.
The sample bags should be kept clean and transported in special protecting bags.
The samples should be stored at temperatures above 15ºC (59ºF)
Samples have to be analysed as soon as possible but never later than 30 hours after they were collected (according to the European Standard). The reason is the following: Over time, a sample will lose odour in the bag. A sample with more odour loses odour faster than a sample with less odour. As a consequence, if the samples are analysed after a long period, the difference between treated and untreated samples will become smaller. This is best seen in the adjacent figure, where the drop lines represent the difference between treated and untreated air.

3. Guidelines for certified olfactometric measurements

The samples which were collected following the guidelines in Section 2 above should be analysed according to the European Standard CEN 13725. For more detailed instructions we refer the reader to that document. Here only the most important points are highlighted. To perform a good analysis the following criteria should be met:

The odour panel should exist of at least 8, but preferably more persons.
The panel members must be selected by their ability to smell n-butanol. A person who can smell n-butanol at a concentration below 20 ppb is too sensitive. A person who cannot smell n-butanol at a concentration below 80 ppb is not sensitive enough. In both cases the person should not be used for analyses. Ideally the panel should have an average n-butanol detection level of 40 ppb, so a panellist who detects n-butanol at 50 ppb should be offset by a panellist who smells n-butanol at 30 ppb.
Every sample should be analysed twice by each panel member.
For each sampling point at least three independent samples should be analysed.
The average detection level of n-butanol of the panel, measured on the day of analyses, should be mentioned in the report.

4. Guidelines for indicative olfactometric measurements

An indicative olfactometric measurement is a stripped down version of a certified test. This is applied by some agencies and will reduce the costs significantly. Most of the time these indicative results cannot be used for the authorities, who require a certified measurement, but they can be used to determine the maximum efficiency.

This test will not give a concentration in odour units per m3 but a dilution factor per m3. This is the same dimension, but it is named different to avoid misunderstanding about what results are certified. With some agencies it is also possible to start analysing with an indicative measurement and finish one of the samples with a certified measurement. During the test one determines which samples deliver the best abatement efficiency.

If you want to analyse one of the samples for a certified test, you should take in account that more sample air is needed. In order to perform good analyses follow these guidelines:

The odour panel should consist of at least 4 persons.
The panel members should be selected using n-butanol sensitivity as described in Section 3 above.
Every panelist should analyse each sample once.
For each sampling point at least two independent samples should be analysed.
This procedure is comparable to a certified measurement.

Industrial Odour Problems Odour Abatement Process Industrial odour nuisance and problems Legislation in odour nuisance Test centers for odour nuisance Alternative solutions	Test centers for odour nuisance AEROX® procedure to collect a proper odour sample Rev. 030109 This handout describes procedures for performing odour measurements according to the Aerox standards. To determine an abatement efficiency, the guidelines in Sections 2, 3 and 4 below should be followed. 1. Indicative test with a small panel In order to determine the difference in odour emissions between a treated sample and an untreated sample the following indicative test can be performed. During a pilot test, treated and untreated samples can be collected from the pilot system using Nalophan sample bags. The best method is to collect both samples behind the Aerox-Injector, just before the fan. A sample barrel may be used to collect the samples. By switching the Aerox -Injector pilot system on and off, treated and untreated samples can be obtained. These samples can be collected without pre-dilution and within a short period of time. The samples can be smelled by a small panel, for instance 2 to 4 non-qualified persons, to determine whether there is any difference in odour sensation between treated and untreated air. NOTE: It is not possible to determine an abatement efficiency using this qualitative test. 2. Guidelines for collecting an odour sample for olfactometric analyses To collect a sample for proper olfactometric analysis, please adhere to the following guidelines: All pieces of equipment that the sample comes into contact with should be made from Teflon, stainless steel, glass, Tedlar or Nalophan plastic. All other materials add odour to the sample. For each sample a new filter should be used in the sampling equipment to exclude dust and fibres. It is preferable not to use a flat filter in order to avoid a layer of odorous dust on the filter. Each sample should be diluted with enough odour free nitrogen to prevent condensation in the sample bag. Odour free nitrogen is obtained by using an active carbon filter and an absolute dust filter. During sampling an amount of nitrogen is mixed with the sampled air stream, and this should be done dynamically. The exact dilution factor should be measured for each sample. Dilution ratios of up to 10 times can be checked by measuring the oxygen concentration in a diluted sample compared to an undiluted sample. It is necessary to measure the oxygen concentration to a precision of 0.1% or better to do this. When larger dilutions are used the dilution system should be calibrated at site by measuring the pressures of the sampled air stream and the diluted air stream. For each sample a new sample bag must be used. Clean tubing should be used between the sampling port and sample bag for each sample. Treated and untreated samples should be collected simultaneously in order to prevent influences from process fluctuations. Before taking the sample the sample bags have to be pre conditioned. This can be achieved by flushing the sample bags for a short period. The sample should be collected for at least 30 minutes in order to average influences from short term process fluctuations. A longer sample collection time will give a more representative average. The sample should be collected using the "reversed lung" principle (up to 5 times dilution), or by means of the Venturi principle. These techniques ensure odorous air will not be cross-contaminated (by a pump, for example) during sampling. Samples should be large enough for all necessary analyses in the laboratory. The sample bags should be kept clean and transported in special protecting bags. The samples should be stored at temperatures above 15ºC (59ºF) Samples have to be analysed as soon as possible but never later than 30 hours after they were collected (according to the European Standard). The reason is the following: Over time, a sample will lose odour in the bag. A sample with more odour loses odour faster than a sample with less odour. As a consequence, if the samples are analysed after a long period, the difference between treated and untreated samples will become smaller. This is best seen in the adjacent figure, where the drop lines represent the difference between treated and untreated air. 3. Guidelines for certified olfactometric measurements The samples which were collected following the guidelines in Section 2 above should be analysed according to the European Standard CEN 13725. For more detailed instructions we refer the reader to that document. Here only the most important points are highlighted. To perform a good analysis the following criteria should be met: The odour panel should exist of at least 8, but preferably more persons. The panel members must be selected by their ability to smell n-butanol. A person who can smell n-butanol at a concentration below 20 ppb is too sensitive. A person who cannot smell n-butanol at a concentration below 80 ppb is not sensitive enough. In both cases the person should not be used for analyses. Ideally the panel should have an average n-butanol detection level of 40 ppb, so a panellist who detects n-butanol at 50 ppb should be offset by a panellist who smells n-butanol at 30 ppb. Every sample should be analysed twice by each panel member. For each sampling point at least three independent samples should be analysed. The average detection level of n-butanol of the panel, measured on the day of analyses, should be mentioned in the report. 4. Guidelines for indicative olfactometric measurements An indicative olfactometric measurement is a stripped down version of a certified test. This is applied by some agencies and will reduce the costs significantly. Most of the time these indicative results cannot be used for the authorities, who require a certified measurement, but they can be used to determine the maximum efficiency. This test will not give a concentration in odour units per m3 but a dilution factor per m3. This is the same dimension, but it is named different to avoid misunderstanding about what results are certified. With some agencies it is also possible to start analysing with an indicative measurement and finish one of the samples with a certified measurement. During the test one determines which samples deliver the best abatement efficiency. If you want to analyse one of the samples for a certified test, you should take in account that more sample air is needed. In order to perform good analyses follow these guidelines: The odour panel should consist of at least 4 persons. The panel members should be selected using n-butanol sensitivity as described in Section 3 above. Every panelist should analyse each sample once. For each sampling point at least two independent samples should be analysed. This procedure is comparable to a certified measurement. Print	Extra information Contact Asia Australia Europe Middle East America Other countries
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