Bag filter housing
Where wire mesh ends at 50 µm, the filter bag goes down to 1 µm. It is fitted in the same support basket that would also hold a fine mesh screen – nothing changes on the housing.
For us, the bag filter is therefore not a separate unit but a version of the strainer element. This has a practical advantage: you can switch between screen and bag without replacing the strainer.
ISO 9001 · TÜV-approved welding shop AD2000-HP0 · PED 2014/68/EU
Operating principle
The medium flows from the inside to the outside through the bag. Whatever is retained stays in the bag – not in the housing. The stainless steel support basket takes up the pressure; without it, the bag would not withstand the flow.
At the top, the bag has a plastic ring that keeps it in shape and seals it against the rim of the basket. To change it, the cover is opened, the bag is pulled out by the ring and a new one is fitted – without tools, without cleaning.
Bag material
The material determines resistance and filtration grade. Which one is right depends on the medium and the temperature – and on how fine the separation really needs to be.
The standard: resistant to most aqueous media, acids and alkalis, and with 1 to 300 µm the widest filtration range. Unless there is a reason against it, PP is the first choice.
For media where polypropylene reaches its limits. The filtration range goes from 1 to 200 µm; the fibre is more dimensionally stable and withstands higher temperatures.
On request, for example as a woven mesh bag instead of felt – then washable and reusable. Useful where the bag is not intended as a consumable.
The bag size does not follow the nominal size but the basket: sizes 1 to 4 are standardised, and the same size fits every housing designed for it. This makes procurement simple – replacement bags are not a special part.
Bag and fine mesh screen are not mutually exclusive. If the screen sits upstream of the bag, it retains coarse particles and extends the service life of the more expensive stage. Economically, this is usually the better way: a screen is cleaned, a bag is disposed of.
The bag is a replacement part, not a permanent component – it is replaced, not cleaned. That is why the pressure rating is lower than for a strainer with a strainer basket. Where fine separation and high pressure come together, a pleated wire mesh is the better solution – see Mesh size and filtration grade.
Housing
Because the bag is an element, any of our basket designs can serve as the housing. Which one is right is decided not by the bag but by the installation situation.
Compact
The most common choice in small nominal sizes: quick-opening closure without tools, suspended installation, fast bag change.
Standard
For larger nominal sizes and higher flow rates.
Simplex strainer →Without shutdown
When the bag change must not interrupt operation: switch over, change, keep running.
Duplex strainer →We make bag filter housings in carbon steel or stainless steel in our own workshop, welded and with the connections the installation point requires. For example, a simplex strainer in carbon steel or stainless steel can be designed to take filter bags.
The bags themselves are consumables. On request we procure them to your specification, so that housing and element match from the start.
No. The bag is fitted in the same support basket that otherwise holds the fine mesh screen. If you already operate a basket, simplex or duplex strainer, it can be converted in many cases – tell us the dimensions of the existing basket and we will check.
The limit is about 50 µm. Above that, wire mesh has the advantage: it is cleaned and reused, withstands higher pressures and causes no follow-up costs. Below that, there is hardly any way around the bag. With a high dirt load, a combination of both is usually the most economical solution.
By the differential pressure. It rises as soon as the bag clogs – but unlike with a screen, faster and steeply towards the end. A differential pressure gauge on the strainer therefore belongs to every bag design.
Ask us about it – we define material, filtration grade and size together with you, so that replacements can later be procured without queries. Sizes 1 to 4 are standardised.
All custom designs at a glance: Custom strainers
Tell us the medium, flow rate, pressure and temperature as well as the filtration grade to be achieved. You will receive a design proposal with housing, bag material and size. Where a fine mesh screen is more economical, we will tell you.
