Every modern SCR system has its own fine filter built into the vehicle's AdBlue® supply module. So a fair question from fleet and workshop managers is whether they need another filter on the site tank or dispensing pump. The short answer: for small drums used once and discarded, usually not. For bulk tanks, IBCs on gravity feed and any dusty site, an inline filter is low-cost insurance.
What the vehicle filter already does
The filter inside the vehicle protects the dosing pump and injector from small particles. It is designed to catch the odd speck, not to clean up a dirty supply. When it loads up, the vehicle may throw a warning, lose dosing pressure and eventually derate. Replacing an SCR filter on a truck is a workshop job, and if dirt gets past it the injector and catalyst are next in line.
In other words, the vehicle filter is the last line of defence. You don't want it doing the work that should happen before AdBlue ever reaches the filler neck.
When a site filter makes sense
An inline filter, commonly around 10 micron, fitted after the pump protects your nozzle, meter and every vehicle you fill. It is most worthwhile when:
- You run a bulk tank. Large tanks are filled from tankers and vented to air, so over months dust and fine debris can settle in the bottom. A filter stops that sediment being pumped out when levels run low.
- The site is dusty. Quarries, mines, farms, civil jobs and unsealed depots put a lot of fine dust in the air, and some of it will find its way into vents and open lids.
- Several people use the equipment. The more hands on the nozzle, the more chance of it being dropped in the dirt or left lying on the ground.
- You fill a lot of vehicles from one point. One contamination event at a shared bowser can affect a whole fleet, not just one truck.
- You use a K24-type or pulse meter. Meters have fine internal parts and small particles affect accuracy and wear.
For a single 10 L or 20 L drum poured straight into a ute with a clean, dedicated spout, a site filter adds little. The drum is sealed until opened and used quickly.
What filtration will not fix
This is the part that catches people out. A filter removes particles. It does not remove anything dissolved in the liquid. If AdBlue is chemically off-spec, filtering it achieves nothing useful. That includes:
- AdBlue diluted with tap water, which adds calcium, magnesium and other minerals
- Product that has been stored hot for too long and broken down (often with an ammonia smell)
- AdBlue that has picked up dissolved metals from brass, copper, galvanised or carbon steel fittings
- Product contaminated with diesel, oil or coolant from reused containers
- Product that simply isn't made to ISO 22241 in the first place
Those problems need to be prevented at the source: buying product that is made and tested to the standard (see our VDA and ISO certification), storing it correctly and using only compatible materials.
Clean handling beats filtering
Filtration works best as a backstop to good habits, not a substitute for them. The basics are:
- Use equipment dedicated to AdBlue only. Never use a pump, hose, funnel or container that has held diesel, oil, coolant or ordinary water.
- Choose compatible materials: stainless steel (304/316), HDPE, polypropylene, EPDM or fluoroelastomer seals. Avoid brass, copper, aluminium and galvanised fittings.
- Keep lids, caps and IBC valves closed between uses.
- Hang the nozzle up in a holster or boot rather than leaving it on the ground.
- Store tanks and IBCs out of direct sun.
- Never top up AdBlue with tap water.
One thing to do today: walk out to your AdBlue dispensing point and look at where the nozzle lives when it isn't in use. If it sits on the ground, in a bucket or hooked on a dirty rail, fit a proper nozzle holster or cap. It costs very little and removes the most common entry point for grit.
Choosing and fitting a filter
If you do fit one, put it on the delivery side after the pump so everything going to the nozzle passes through it. Make sure the housing and element are rated for AdBlue, and use EPDM hose and compatible fittings throughout. Fit it where it is easy to reach, because an element that is awkward to change tends not to get changed. Filters, housings and compatible hose are listed on our accessories page.
Watch for slowing flow at the nozzle. On a system that used to fill quickly, a gradual drop in flow is often the first sign that the filter element is loading up and due for replacement.
How Liquidia can help
Liquidia supplies ISO 22241 compliant, VDA-licensed AdBlue that is lab-tested every batch, along with Piusi pumps, filters and nozzles for fixed and mobile sites. Browse the online store or talk to us about a complete bulk tank and dispensing setup.