Pre-filters
The pre-filter is the first stage of the airclean series and carries ewo's red colour coding. It retains 99.99 % of the solid contaminants from 1 µm and reduces the residual oil content to 0.5 mg/m³ – that is particles 2 and oil 3 to ISO 8573-1. Two sizes, 50 and 60, cover G ¼ to G ¾.
How the pre-filter works
The filter element is made of borosilicate microglass fibre web on a stainless steel support core, with a polyester fibre fleece drainage layer on the outside. The air flows from the inside out: solids stay in the web, separated liquid travels down the drainage layer into the bowl. Housing and bowl are painted aluminium, the end caps PA, the seal an NBR O-ring. The filter works between +1.5 and +80 °C at a maximum of 16 bar; with the automatic add-on drain valve A the permissible operating pressure drops to 12 bar, and the valve itself needs at least 4 bar to close.
Choosing the right pre-filter
The volume flow decides, not the pipe diameter: at p₁ = 7 bar and only 0.1 bar pressure drop the devices range from 583 l/min to 3,666 l/min. Sizing tight costs pressure drop and element life. The version with a differential pressure gauge pays off wherever the change interval should follow the actual load rather than the calendar. Mounting is vertical.
| Product group | Connection | Size | Max. pressure | Items |
|---|---|---|---|---|
| Pre-filter (VF) airclean | G ¼, G ⅜, G ½, G ¾ | Size 50, Size 60 | 16 bar (12 bar with automatic attachment outlet valve A) | 10 |
Typical applications
- Inlet stage ahead of microfilters and activated carbon filters
- Protection of tools, cylinders and valves against particles and water
- Machine supply lines in production and assembly
- Pre-filtration ahead of dryers and sensitive measuring equipment
- Retrofitting on existing treatment sections
Your advantages
- Worldwide shipping of all compressed air components and service units
- Large stock levels for many products – current lead time available on request
- Spare parts and service kits available
- Fast shipping via UPS (parcel) or freight forwarder (pallets), express delivery available on request
- Extensive hands-on application know-how
- Personal advice on selecting the right component
- Resellers receive volume-based discounts on request
- Large companies, public authorities and government agencies can order on account (request via our contact form)
Frequently asked questions
What is the colour coding for?
ewo marks the three filter stages by colour: pre-filter red, microfilter blue, activated carbon filter black. In a row of two or three housings you can see at a glance which element belongs where – and do not reach for the wrong one when changing.
Why from the inside out?
Because the solids then stay inside the element and do not fall onto the clean air side when it is removed. The separated liquid runs off outside via the drainage layer instead of building up in the medium.
Differential pressure gauge – necessary or luxury?
Useful. The element clogs over time, the pressure drop rises, and every additional bar of pressure drop costs compressor power. The gauge shows when a change pays off – instead of replacing by the calendar.
