Understanding DEF Testing and ISO 22241 Compliance
Modern diesel engines are cleaner and more efficient than ever before, but meeting today’s strict emissions standards takes more than advanced hardware. It requires Diesel Exhaust Fluid (DEF), a simple solution that plays a crucial role in reducing nitrogen oxide (NOx) emissions.
Also known globally as:
- AdBlue® (Europe, Asia)
- BlueDEF® (North America)
- Arla 32® (Brazil)
DEF plays a significant and influential part in global clean air initiatives and regulatory compliance.
Effective DEF performance depends on consistent quality control. Rudolph Research Analytical provides tools that help meet these standards.
Why Accurate DEF Testing is Vital
DEF is composed of 32.5% high-purity urea, a nitrogen-based compound, mixed with demineralized water. Urea in DEF helps reduce harmful nitrogen oxide (NOx) emissions in diesel engines through the Selective Catalytic Reduction (SCR) system. Though it seems simple, any small variations in purity, concentration, or density can cause major issues:
- Underperforming: Leads to failed NOx reduction and non-compliance
- Over-concentrated: Risk of forming solid deposits that damage catalytic reduction (SCR) systems
- Improperly formulated: Can trigger expensive engine repairs or regulatory fines
To mitigate these risks, the ISO 22241 standard outlines precise requirements for DEF composition, handling, and testing.
Laboratories, wholesalers, and producers must test and verify DEF regularly to stay compliant and protect the equipment that relies on it.
Refractive Index Testing
A core requirement of ISO is the precise measurement of refractive index, which correlates directly with urea concentration. This value must be measured at 20°C with a high level of accuracy and repeatability.
Instruments That Support ISO 22241 Standards
Refractometers play a key role in verifying urea concentration in DEF. Commonly used instruments for this purpose:
ISO 22241 Compliance Lab Requirements:
1. Wavelength Accuracy – ISO 22241 requires 589.3 nanometers ± 5; both the J57 and J157 meet this optical standard.
2. Measuring Range – Must cover 1.33000 to 1.39000; Rudolph instruments exceed this requirement.
3. Temperature Stability – Precise 20°C ± 0.1 with solid-state Peltier control.
4. Resolution – Required to the fifth decimal place. Rudolph delivers exactly that.
5. Calibration Accuracy – Max deviation is ±0.00005; Rudolph exceeds this with ±0.00002 RIU.
6. Urea Content Calculation – The J57 HA requires manual biuret correction; J157 HA allows direct entry for ease of use.
7. Monthly Calibration – Simplified with a kit containing ISO 17034 certified urea standards.
8. Calibration Fluids – Certified calibration fluids simulate DEF properties and ensure accurate, traceable results during routine calibration.
ASTM Proficiency Testing with DEF
In addition to ISO 22241 standards, ASTM International also provides guidelines that support Diesel Exhaust Fluid quality testing. ASTM is a globally recognized organization that develops and maintains 12,500 active testing standards used to measure materials, products, and systems across a wide range of industries.
ASTM’s Diesel Exhaust Fluid (DEF) Proficiency Testing Program provides laboratories with a statistical quality assurance tool to benchmark, enhance, and sustain top performance in applying ISO methods worldwide. Participants can assess their laboratory’s strengths and weaknesses while regularly comparing test results and statistical metrics with those of other labs.
Refractometer Options for Different Lab Needs
- J57 HA-AB: Compact footprint, strip printer connectivity.
- J157 HA-AB: Network connectivity, wider printer options, additional modes for flexibility.
- J357 and J457: Advanced refractometers for labs that need to test beyond DEF or AdBlue.
DEF Density Testing and Its Contribution to Quality Assurance
While refractive index confirms urea concentration, density testing is equally critical for verifying DEF composition and identifying impurities. Small deviations can have serious consequences:
- Low density: Indicates under-concentration, reducing emissions control
- High density: Suggests possible crystallization, risking engine damage
According to ISO 22241, the acceptable density range for DEF is 1.087 to 1.093 g/cm³ at 20°C.
DM Series: Precision Density Meters Built for DEF Testing
Rudolph’s DM Series density meters are specifically built for DEF testing and include:
- Oscillating U-tube technology for lab-grade accuracy
- Tight temperature regulation to maintain 20°C throughout testing
- Viscosity correction, ensuring consistent results across varying conditions
- Video View® for Air bubble detection, preventing inaccurate measurements
- Auto-generated Certificate of Analysis (COA) for compliance
Who Uses Rudolph for DEF Testing?
Thousands of labs worldwide trust Rudolph for precise, reliable DEF analysis. Common users include:
- DEF manufacturers
- Bulk wholesalers
- Retail fuel suppliers
- Independent testing labs
Why Labs Choose Rudolph for DEF Testing
- Full ISO 22241 compliance
- High precision with low maintenance
- Reliable calibration with traceable standards
- Scalable systems for small labs or large operations
- Responsive technical support and application training
Equip Your Lab for Compliance
DEF quality is not optional, it’s mission critical. With increasingly tight regulations, DEF testing is no longer just the best practice. It’s a requirement.
Contact Rudolph Research Analytical
Whether you’re a DEF producer, wholesaler, or retailer, ISO 22241 compliance is essential. Rudolph refractometers and DM Series Density Meters make DEF and AdBlue testing accurate, reliable, and easy.
Contact Rudolph Research Analytical for a consultation, demo, or quote and see why labs worldwide trust Rudolph for DEF testing and ISO 22241 compliance.
