AdBlue is the brand name of a 32.5% aqueous urea dilution. Truck engines with SCR catalytic technology use AdBlue to reduce the NOx-content in the exhaust gas stream. This reduction is necessary to reach the demanding limits for exhaust gases. The exact composition of AdBlue is defined in DIN 70070.
AdBlue is filled into a separate tank. Fuel in the AdBlue tank will permanently damage or destroy the SCR system, causing high cost of repairs. This can be tested for by using Machery Nagel test strips – Oil test paper
Test procedure
The oil test paper is moved back and forth in the tank 3-5 times. A dark discoloration of the test paper indicates the presence of fuel.
Fuel does not mix with AdBlue. It forms small droplets or a thin layer on the surface of AdBlue. To give a positive reaction the test paper must come in contact with fuel in the tank.
Detection limit
50 mg/l fuel in AdBlue give a weak positive reaction. 100 mg/l fuel in AdBlue result in a clearly visible color reaction.
Product data and ordering information: Oil test paper
| Type | Qualitative test paper |
| Presentation | Pack of 100 strips 20×70 mm |
| Color reaction | pale blue to dark blue |
| Limit of sensitivity | Petroleum ether: 250 mg/l |
| Gasoline: 10 mg/l | |
| Fuel oil: 5 mg/l | |
| Lubricating oil: 1 mg/l | |
| Reference | 1138883 |
The full range of Macherey Nagel test strips are available from Camlab in the uk
