Diesel Exhaust Fluid

Diesel exhaust fluid (DEF, AdBlue, AUS 32) is a solution of 32.5% ± 0.5% high-purity urea (CAS 57-13-6) in demineralised water, made to ISO 22241, the specification every SCR engine maker refers to. Global Chemicals LLC supplies it from stock in Muscat in 10 L and 20 L containers, 200 L drums, 1,000 L IBCs and bulk, to fleet operators, oilfield and drilling contractors, construction, mining, power-generation and marine users across Oman.

What it does. Engines with selective catalytic reduction (SCR) inject DEF into the hot exhaust ahead of a catalyst; the urea breaks down to ammonia, which converts nitrogen oxides into nitrogen and water and cuts NOx emissions by up to about 90%. Euro 6 trucks, US EPA 2010 on-road engines and Tier 4 off-road machines depend on it, and a vehicle that runs out or is filled with the wrong fluid will lose power and log a fault. Consumption is roughly 3–5% of diesel burned, so a truck using 300 litres of diesel a week needs about 9–15 litres of DEF.

Why the specification matters. The 32.5% concentration is the eutectic: it gives the lowest freezing point of any urea solution, about −11 °C, and both weaker and stronger solutions freeze at higher temperatures. ISO 22241 also caps biuret at 0.3% and aldehydes, phosphate and metals such as calcium, iron, copper and sodium at parts-per-million levels, because those poison the SCR catalyst or block the dosing injector. Fertilizer urea dissolved in tap water does not meet it and damages SCR systems; never dilute DEF or top it up with water.

Storage and handling in a hot climate: DEF slowly hydrolyses above about 30 °C, releasing ammonia and losing strength, and ISO 22241-3 gives its minimum shelf life as about 18 months at 25 °C, 12 months at 30 °C and 6 months at 35 °C; above 35 °C each batch should be tested before use. Store it indoors or in the shade, in closed HDPE or stainless containers only, never in mild steel, copper, brass or aluminium, which it corrodes and which contaminate it. Use dedicated funnels and pumps. It is non-flammable and low in hazard; rinse spills with water, as it dries to white urea crystals. Every batch carries a certificate of analysis to ISO 22241.

Delivery is same day within Muscat, next day to Sohar, Salalah and Duqm, to rig sites and camps in the interior by arrangement, and by road across the GCC with a certificate of origin. Request a quote with the pack size and monthly volume; the oilfield chemicals guide linked on this page lists the related products.