Air Auto Filter Specification Example for City Buses: Budget Line
Air Auto Filter Specification Example for City Buses: Budget Line
This is a worked specification for air auto filter in a budget line programme. It is the document we would send a buyer who asks what exactly they are getting: the material, the dimensions that are actually controlled, the finish, and the checks that happen before anything is packed.
The budget line version exists because the duty cycle on city buses is not the same as on a showroom vehicle. Where the two are specified identically, something fails later — usually packing that arrived crushed at the port.

Example specification
| Item | Air Auto Filter |
|---|---|
| Application | City Buses |
| Version | Budget Line |
| Base material | Silicone |
| Controlled dimensions | 5 key dimensions, recorded per lot |
| Tolerance band | ±0.2 mm |
| Finish | as machined |
| MOQ | 2,000 pieces per specification |
| Sampling | 10 working days, 5 days per revision |
| Compliance | ECE R90 |
How the example is built up
- Start from the duty cycle, not from the catalogue photograph.
- Fix the base material in writing — Silicone, in this example.
- List the dimensions that are actually controlled and the tolerance on each.
- Name the finish and what it has to survive.
- State the inspection level and who pays when a lot fails.

Processes involved
- laser cutting
- assembly line testing
- powder coating
- precision stamping
- injection moulding
- robot welding
Where this example applies
Programmes that run budget line most often specify this build for city buses. Related applications include long-haul trucks, racing teams, camper conversions, aftermarket retail, delivery vans.
Checks before packing
- Dimensional report against the approved drawing.
- AQL 4.0 sampling on the finished lot.
- Finish inspection under agreed lighting.
- Carton drop test on the first lot of a new packing specification.
Questions buyers ask
What testing is included?
Standard lots ship with dimensional and hardness reports. ECE R90 documentation is issued with the shipment when your market requires it.
Do you handle mixed containers?
Yes. Most programmes consolidate several part numbers into one container to keep freight sensible at 2000 pieces per line.
Can the specification be held on file?
Yes. Once approved, the specification is recorded against your part number so a reorder reproduces the ECE R90-compliant build instead of a fresh interpretation.
How is packing specified?
Individual packing, inner box quantity and carton marking are confirmed at quotation stage so the cartons arrive ready for your warehouse.
Send the part number, the annual volume and the target market, and we will come back with a specification and a sampling plan.



