ISO 22241 Diesel Engines - NOx Reducing Agent AUS 32

The “ISO 22241 Diesel engines - NOx reducing agent AUS 32” standard, developed by the International Standards Organization (ISO), consists of a number of subsections published under the same title. Namely,

• The standard “ISO 22241-1 Part 1: Quality requirements” describes the quality characteristics of the NOx reducing agent AUS 32 (aqueous urea solution) needed to operate selective catalytic reduction converter systems in diesel engine vehicles. Selective catalytic reduction converter systems are particularly suitable for selectively reducing nitrogen oxide (NOx) emissions from diesel engines.

The quality characteristics of AUS 32 are specified in the table provided in the standard and are continuously monitored by the manufacturer in accordance with a production control plan. Compliance with the limits in the table is verified by the specified test methods or other methods specified by a recognized standard. However, in case of disagreement, the methods specified in the table are accepted as arbitration methods.

• The standard “ISO 22241-2 Part 2: Test methods” describes the test methods required to determine the quality and chemical properties of the NOx reducing agent AUS 22241 (aqueous urea solution) specified in the ISO 1-32 standard.

In the test for determining the total nitrogen and urea content, the sample is burned at high temperatures in a stream of oxygen. After the nitrogen oxides formed have been reduced to elemental nitrogen and any interfering products of combustion have been removed, the nitrogen is measured with a thermal conductivity detector. The urea content is calculated by subtracting the nitrogen content of biuret from the determined total nitrogen.

• The standard “ISO 22241-3 Part 3: Handling, transport and storage” describes best practice recommendations and requirements for the handling, transport and storage of AUS 32. These recommendations and requirements are necessary to ensure the proper operation of selective catalytic reduction converter systems and to maintain the specified quality of AUS 32 from the point of manufacture to the point at which it is filled into the onboard tank of a vehicle or other application.
• The standard “ISO 22241-4 Part 4: Refill interface” describes the refill interface for the NOx reducing agent AUS 22241, which complies with the ISO 1-32 standard, required to operate converters with selective catalytic reduction exhaust after-treatment systems. This standard specifies the minimum functional and geometrical requirements for an open refill system in order to ensure compatibility between the on-board refill system and the off-board refill system. The compatibility conditions for a closed refill system are included in the annex of the standard (Annex A). This standard applies to commercial vehicles and buses designed to use fixed off-board refill systems, as defined in the ISO 3833 standard, with a gross vehicle mass exceeding 3,5 tonnes. This standard also applies to nozzles for fixed off-board refill systems.
• The standard “ISO 22241-5 Part 5: Recharge interface for passenger cars” describes the requirements for diesel engine road vehicles using selective catalytic reduction technology. These requirements are primarily intended for use by passenger cars and light commercial vehicles, including buses, with a gross vehicle mass not exceeding 3,5 tonnes, but may also be used by vehicles with a gross vehicle mass exceeding 3,5 tonnes. This standard includes a recharge interface for the NOx reducing agent AUS 22241, in accordance with ISO 1-32, required to operate converters with selective catalytic reduction exhaust after-treatment systems. This standard specifies the essential functional and geometrical requirements for the recharge system to ensure compatibility between the on-board recharge system and the off-board recharge system. For light commercial vehicles and buses with a gross vehicle mass not exceeding 3,5 tonnes, the open recharge system specified in ISO 22241-4 may be used.

Today, cars, trucks, and other applications using diesel engines must meet stringent emissions requirements from the U.S. Environmental Protection Agency (EPA). To meet these requirements, many diesel engine manufacturers use selective catalytic reduction, an emissions aftertreatment technology that converts nitrogen oxides (NOx) in the diesel engine exhaust stream into nitrogen and water vapor, two natural components of the air we breathe.

AUS 32 (diesel exhaust fluid) is injected into the diesel exhaust stream, and heat from the exhaust, fluid, and a catalyst converts nitrogen oxides into harmless gases. Diesel exhaust fluid is a 32,5 percent solution of technically pure urea in purified water.

For the selective catalytic reduction unit to function properly, it must meet a rigorous purity standard, AUS 32. This standard is intended to ensure that diesel exhaust fluid used in selective catalytic reduction-equipped cars and trucks has the purity and emission control system and environmental protection quality required by diesel engine manufacturers.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "ISO 22241 Diesel engines - NOx reducing agent AUS 32" standard are also provided to businesses.