Once you've decided a site filter is worth having on your AdBlue® dispensing system, three practical questions follow: how fine should it be, where does it go, and how often should the element be changed? Getting these right means the filter protects your equipment and vehicles without choking the flow or being forgotten about.
Choosing a micron rating
A micron is one thousandth of a millimetre. The rating on a filter element tells you roughly the particle size it is designed to stop. For site dispensing of AdBlue, a rating of around 10 micron is common. It is fine enough to catch the grit, dust and debris that cause problems in nozzles, meters and vehicle SCR filters, while still allowing reasonable flow from typical 12 V, 24 V and 240 V pumps.
Some things to weigh up:
- Finer is not automatically better. A much finer element loads up faster and restricts flow more, which can strain a small pump and slow filling.
- Coarser elements let more through. A coarse strainer protects a pump from large debris but offers less protection to the vehicle.
- Match the pump and flow rate. Check the filter housing's rated flow against your pump. An undersized housing will drop pressure even with a clean element.
- Use AdBlue-rated parts. The housing, element and seals need to be compatible with AdBlue. Stainless steel, polypropylene and HDPE bodies with EPDM or fluoroelastomer seals are suitable. Avoid brass, copper, aluminium and galvanised components.
Where to fit the filter
The usual position is on the delivery side, after the pump and before the meter and nozzle. That way every litre going to a vehicle passes through the filter, and the meter is protected as well.
- Tank or IBC outlet – a suction strainer or foot valve here protects the pump from larger debris sitting in the bottom of the tank.
- Pump
- Inline filter – the main fine filter, around 10 micron.
- Meter – K24-type digital meter or pulse meter for fleet systems.
- Hose, reel and nozzle – EPDM hose and an auto shut-off nozzle.
On a gravity feed kit from an elevated IBC there is no pump to push through a fine element, so flow is limited by the height of the IBC. A fine filter can slow gravity filling noticeably. If you want filtration on a gravity system, choose a low-restriction housing and expect to change elements more often to keep flow up.
Wherever it goes, mount the filter where it can be reached easily, with room to unscrew the bowl or canister and a tray or rag handy to catch drips. If changing the element means lying under a tank stand, it won't happen on time.
Setting change intervals
There isn't one correct interval for every site. How quickly an element loads depends on how clean the tank is, how dusty the site is and how many litres go through it. Start with the filter manufacturer's recommendation and adjust from what you see. Useful triggers for a change include:
- Reduced flow at the nozzle. If a truck that used to fill quickly now takes noticeably longer, check the filter first.
- A set volume or time. Many sites change on a calendar basis or after a set number of litres, whichever comes first.
- After any tank work. Cleaning, moving or repairing a tank can stir up sediment. Change the element afterwards.
- After a suspected contamination event. If a lid was left off in a dust storm or the nozzle was dropped in mud, change it and inspect the old one.
One thing to do today: write the date and the meter reading on the filter housing with a paint marker, or on a tag cable-tied to it. Next time you change it, you'll know exactly how many litres and how many weeks that element lasted, and you can set a realistic interval for your site from real numbers.
Changing an element cleanly
The change itself is a chance to introduce contamination if done carelessly. Isolate the pump, relieve pressure, and open the housing over a clean container. Wear gloves and eye protection. Fit the new element straight from its packaging without laying it on a bench, check the seal is seated, and wipe the housing clean before closing it. Run a small amount of AdBlue through to purge air before filling a vehicle.
Look at the old element before binning it. Fine grey dust points to vent or lid issues; rust-coloured particles suggest an incompatible metal component somewhere in the system; oily residue means something is badly wrong and the supply should be checked before further use. Any spilt AdBlue should be rinsed away with plenty of water, as it dries to white urea crystals.
Remember that a filter only deals with particles. It can't make off-spec product good, so it works alongside sound storage and product that is made to ISO 22241.
How Liquidia can help
Liquidia supplies Piusi pumps, meters, nozzles and AdBlue-compatible filters, and can set up complete systems for fixed sites. See the accessories range or ask about a full bulk tank and dispensing installation.