MISCO Digital Handheld Refractometer

The DEFinitive choice in DEF Testing.

The MISCO digital refractometer is the ideal instrument for testing DEF to prevent the use of fluid that is outside expected values. MISCO refractometers meet or exceed the requirements of ASTM D7821 – 12, Standard Test Method for Field Test Determination of Urea Concentration in Diesel Exhaust Fluid (DEF).

The American Petroleum Institute (API), a non-profit trade association and advocacy group for the petroleum and natural gas industry, is charged with certifying producers of Diesel Exhaust Fluid (DEF) for Selective Catalytic Reduction (SCR) equipped diesel engines in North America. The best way to ensure a suitable DEF fluid is only to purchase urea, which carries API certification, and frequently test the fluid with a MISCO refractometer to make sure that it meets quality specifications.

Urea Refractometer for Testing Urea-Based Diesel Exhaust Fluid (DEF / AdBlue) Concentration

The proper concentration of Urea in Diesel Exhaust Fluid (DEF) is crucial to mitigating harmful NOx emissions and prolonging the life of expensive SCR components.

A refractometer will DEFeat those seeking to DEFraud.

Diesel Exhaust Fluid (DEF) has been a reality for trucks, buses, and highway vehicles powered by diesel engines for some time. Tier IV guidelines now affect off-road equipment, such as excavators, bulldozers, skid steers, commercial construction equipment, farm tractors and agricultural equipment, heavy forklifts, and airport ground service equipment. Even diesel-powered stationary equipment such as generators, pumps, and compressors will be required to meet emission requirements.

To comply with EPA regulations, engine manufacturers use Selective Catalytic Reduction technology, which requires an exact concentration of liquid urea (DEF) to operate correctly. Selective Catalytic Reduction systems utilize liquid urea, a nitrogen-based compound, to treat diesel exhaust gases before entering the catalytic converter. The fluid is known as Diesel Exhaust Fluid (DEF) in the US and AdBlue in Europe. It consists of a precise concentration of aqueous urea in demineralized water. Injected into the hot exhaust gases as a fine mist, urea turns to ammonia and converts harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor.

The best DEFense against diluted DEF.

The proper concentration of Diesel Exhaust Fluid (DEF) is crucial to mitigating harmful NOx emissions and prolonging the life of expensive SCR components. Even concentration variations of as little as +/-0.8% will prevent a DEF fluid from meeting the specifications mandated by the International Standards Organization (ISO). DEF dilution or contamination can impact system performance and maintenance costs. The biggest contamination threat is water dilution, but it is nearly impossible to know if a DEF supply is diluted without the proper tools. 

Get DEFinite results in just seconds.

A MISCO digital refractometer is the ideal method for testing DEF fluid to ensure it is at the correct concentration and has not been tampered with or diluted. It only takes a few drops of DEF and a couple of seconds to perform a test, and the results are precise to +/-0.1% urea concentration. 

Once you place a few drops of the sample into the stainless-steel sample-well, it only takes the press of a single button to initiate a test. Within seconds, the urea concentration is displayed on the large 24-character backlit LCD display. The refractometer can be calibrated to water with the press of a button.

Pre-Configured Refractometers

Easy Order: Here are a few of the most popular Scale Combinations and Refractometer Models. If you require different programming, you can mix and match scales through the Flexible Custom Programming section below, or call customer service for assistance:

Flexible Custom Programming Options

MISCO Palm Abbe Digital Refractometers can be custom-programmed with up to 5 scales to your exact specifications. There are two easy online options to create your customized units from hundreds of measurement scales:

“Build Your Own” Tool

  1. Use the Industry, Application and Fluid filters to quickly find your scales.
  2. Click scale boxes to add scales to your device.
  3. Select Accessories
  4. Add To Cart

Order Refractometer by Scale#

  1. Browse the refractometer scale options in the dropdown tabs below and record the scale numbers you want.
  2. Type in your scale numbers on the Order by Scale# page.
  3. Select Accessories
  4. Add To Cart
DEF - Diesel Exhaust Fluid

Urea % w/w

Scale# 185
UoM: % w/w
Range: 0 to 51
Resolution: 0.1
Precision: 0.1

Urea (g/cm3)

Scale# 187
UoM: Density (g/cm3)
Range: 1.000 to 1.1313
Resolution: 0.001
Precision: 0.00029

Urea (mol/Liter)

Scale# 628
UoM: Molarity (mol/Liter)
Range: 0 to 8.6
Resolution: 0.01
Precision: .02

Urea (nD20)

Scale# 629
UoM: Refractive Index (nD)
Range: 1.3330 to 1.4140
Resolution: 0.0001
Precision: .0001

Urea (ppt)

Scale# 190
UoM: Parts Per Thousands (ppt)
Range: 0 to 460
Resolution: 1
Precision: 1

Urea Freeze Point ºC

Scale# 189
UoM: Freeze Point ºC
Range: 0 to -17
Resolution: 1
Precision: 0.1

Urea Freeze Point ºF

Scale# 188
UoM: Freeze Point ºF
Range: +32 to 0
Resolution: 1
Precision: 0.1
Related: Battery

Sulfuric Acid % w/w

Scale# 117
UoM: % w/w
Range: 0 to 60
Resolution: 0.1
Precision: 0.1

Sulfuric Acid (D113/113°F)

Scale# 783
UoM: Specific Gravity (113°F)
Range: 1.000 to 1.399
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D131/131°F)

Scale# 784
UoM: Specific Gravity (131°F)
Range: 1.000 to 1.397
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D20/20)

Scale# 118
UoM: Specific Gravity (D20/20)
Range: 1.000 to 1.5012
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D30/30)

Scale# 832
UoM: Specific Gravity (D30/30)
Range: 1.00 to 1.491
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D50/50°F)

Scale# 780
UoM: Specific Gravity (50°F)
Range: 1.000 to 1.413
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D60/60°F)

Scale# 450
UoM: Specific Gravity (60°F)
Range: 1.000 to 1.502
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D77/77°F)

Scale# 781
UoM: Specific Gravity (77°F)
Range: 1.000 to 1.405
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D80/80°F)

Scale# 451
UoM: Specific Gravity (80°F)
Range: 1.000 to 1.496
Resolution: 0.001
Precision: 0.001

Sulfuric Acid (D95/95°F)

Scale# 782
UoM: Specific Gravity (95°F)
Range: 1.000 to 1.402
Resolution: 0.001
Precision: 0.001
Related: Brake Fluid

Brake Fluid DOT3 % H2O

Scale# 061
UoM: % Water
Range: 0 to 6
Resolution: 0.1
Precision: 0.5

Brake Fluid DOT3 Boil °C

Scale# 166
UoM: Boiling Point °C
Range: 118 to 252
Resolution: 1
Precision: 5 ºC

Brake Fluid DOT3 Boil °F

Scale# 062
UoM: Boiling Point °F
Range: 244 to 485
Resolution: 1
Precision: 10 ºF

Brake Fluid DOT3 HT Boil °C

Scale# 167
UoM: Boiling Point °C
Range: 107 to 292
Resolution: 1
Precision: 5 ºC

Brake Fluid DOT3HT % H20

Scale# 063
UoM: % Water
Range: 0 to 6
Resolution: 0.1
Precision: 0.5

Brake Fluid DOT3HT Boil °F

Scale# 064
UoM: Boiling Point °F
Range: 225 to 558
Resolution: 1
Precision: 10 ºF

Brake Fluid DOT4 % H20

Scale# 065
UoM: % Water
Range: 0 to 6
Resolution: 0.1
Precision: 0.5

Brake Fluid DOT4 Boil °C

Scale# 066
UoM: Boiling Point °C
Range: 143 to 278
Resolution: 1
Precision: 5°C

Brake Fluid DOT4 Boil °F

Scale# 164
UoM: Boiling Point °F
Range: 288 to 532
Resolution: 1
Precision: 10 ºF

Brake Fluid DOT4+ % H20

Scale# 067
UoM: % Water
Range: 0 to 6
Resolution: 0.1
Precision: 0.5

Brake Fluid DOT4+ Boil °C

Scale# 068
UoM: Boiling Point °C
Range: 158 to 293
Resolution: 1
Precision: 6°C

Brake Fluid DOT4+ Boil °F

Scale# 165
UoM: Boiling Point °F
Range: 316 to 559
Resolution: 1
Precision: 10 ºF
Related: Engine Coolant

Ethylene Glycol % v/v

Scale# 011
UoM: % v/v
Range: 0 to 100
Resolution: 0.1
Precision: 0.1

Ethylene Glycol % w/w

Scale# 012
UoM: % w/w
Range: 0 to 100
Resolution: 0.1
Precision: 0.1

Ethylene Glycol (D20/20)

Scale# 015
UoM: Specific Gravity (D 20/20)
Range: 1.0000 to 1.1153
Resolution: 0.0001
Precision: 0.0001

Ethylene Glycol (g/cm3)

Scale# 379
UoM: Density (g/cm3)
Range: 0.998 to 1.113
Resolution: 0.0001
Precision: 0.0002

Ethylene Glycol Boil °C

Scale# 381
UoM: Boiling Point °C
Range: 100 to 152
Resolution: 1
Precision: 1

Ethylene Glycol Boil °F

Scale# 380
UoM: Boiling Point °F
Range: 212 to 305
Resolution: 1
Precision: 1

Ethylene Glycol Freeze °C

Scale# 014
UoM: Freeze Point ºC
Range: 0 to -59
Resolution: 1
Precision: 1

Ethylene Glycol Freeze °F

Scale# 013
UoM: Freeze Point °F
Range: +32 to -79
Resolution: 1
Precision: 2

PG Freeze °C (GEN)

Scale# 909
UoM: Freeze Point °C
Range: 0 to -51
Resolution: 1
Precision: 1

PG Freeze °F (GEN)

Scale# 908
UoM: Freeze Point °F
Range: 32 to -60
Resolution: 1
Precision: 2

Propylene Glycol % v/v

Scale# 006
UoM: % v/v
Range: 0 to 100
Resolution: 0.1
Precision: 0.1

Propylene Glycol % w/w

Scale# 007
UoM: % w/w
Range: 0 to 100
Resolution: 0.1
Precision: 0.1

Propylene Glycol % w/w (GEN)

Scale# 907
UoM: % w/w
Range: 0 to 100
Resolution: 0.1
Precision: 0.1

Propylene Glycol (D20/20)

Scale# 010
UoM: Specific Gravity (D20/20)
Range: 1.0000 - 1.0460
Resolution: 0.0001
Precision: 0.0001

Propylene Glycol Freeze °C

Scale# 009
UoM: Freeze Point ºC
Range: 0 to -51
Resolution: 1
Precision: 1

Propylene Glycol Freeze °F

Scale# 008
UoM: Freeze Point °F
Range: +32 to -60
Resolution: 1
Precision: 2
Related: Washer Fluid

Methanol % v/v <

Scale# 023
UoM: % v/v <
Range: 0 to 45
Resolution: 0.1
Precision: 0.5 to 0.8

Methanol % v/v >

Scale# 027
UoM: % v/v >
Range: 84 to 100
Resolution: 0.1
Precision: 0.5 to 0.2

Methanol % w/w <

Scale# 024
UoM: % w/w <
Range: 0 to 40
Resolution: 0.1
Precision: 0.5 to 0.8

Methanol % w/w >

Scale# 028
UoM: % w/w >
Range: 80 to 100
Resolution: 0.1
Precision: 0.4 to 0.2

Methanol (D20/20) <

Scale# 025
UoM: Specific Gravity (D20/20) <
Range: 1.000 to 0.935
Resolution: 0.001
Precision: 0.001 to 0.005

Methanol (D20/20) >

Scale# 026
UoM: Specific Gravity (D20/20) >
Range: 0.849 to 0.793
Resolution: 0.001
Precision: 0.001 to 0.005

Methanol Freeze °C

Scale# 022
UoM: Freeze Point °C
Range: 0 to -39
Resolution: 1
Precision: 0.5 to 1.7

Methanol Freeze °F

Scale# 021
UoM: Freeze Point °F
Range: +32 to -39
Resolution: 1
Precision: 1 to 3

Selected Resource:

Refractometers for Field Testing Urea-Based Diesel Exhaust Fluid (DEF / AdBlue) in Selective Catalytic Reduction (SCR) Equipped Diesel Engines.

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Refractometer Platform Choices

Inline-Process Refractometer:

The above scales are also available on any MISCO inline process refractometer or concentration sensors. They are made for continuous concentration measurement of process fluids.

MISCO Handheld Digital Refractometer:

MISCO has the most extensive refractometer scale library on the planet. Don't see what you want? Browse by handheld refractometer model or by refractometer application. Or give us a call. We can help!

From our Q&A Forum

Diesel Exhaust Fluid (2)

Do you know of a refractometer that measures the shelf-life of DEF? I’m not as concerned about our contamination as I am the risk. I’ve heard that comes from it sitting idle in a tank for too long.

A Diesel Exhaust Fluid (DEF) refractometer cannot tell you the quality or shelf-life of the DEF, it can only provide you a measure of urea concentration. However, a concentration measurement can tell you if the DEF is over or under concentrated, and may indicate tampering. The MISCO DEF201 and DEF202 digital handheld refractometers can measure the concentration of urea in DEF but this is a measure of concentration only.

Can you use a refractometer to measure DEF Quantity? Is it acceptable practice to add water to adjust over-concentrated samples?

The Palm Abbe digital refractometer (DEF201 or DEF202) can be used to very accurately measure urea concentration in DEF to +/-0.1%. DEF is a composition of ultra-pure urea and demineralized water. ISO standards call for DEF to be 32.5% (+/-0.8%). If your DEF is over-concentrated, due to evaporation, you can add demineralized water to return the measurement to 32.5%. However, you should NEVER add tap water or well water to a DEF. Doing so can cause irreparable damage to your SCR components.

AdBlue® is a registered trademark of the VDA.