A bag filter housing is a vessel that holds filter bags for the purpose of removing contaminants, solids and particulates from various liquids, under pressure. Liquid enters the bag housing from the top and flows from inside to outside the filter bag. Dirt is contained inside the filter bag which allows for clean removal and disposal. The filter bag is placed inside a perforated basket for support. All housings come with a perforated basket for holding filter bags and bag hold down plate to secure bag in place inside the filter housing.
Components of a Bag Filter Housing
Bag filter housings will usually have the following components:
- Pressure vessel
- Perforated basket for holding filter bags
- Bag hold down mechanism to hold the filter bag in place
- Inlet and outlet connections which can be modified to suit site piping requirements
- Adjustable or welded legs
Sizes of Bag Filter Housings
Industry standard sizes for bag filter housings take 4” diameter and 7” diameter filter bags. These are designated Sizes 1, 2, 3 and 4.
4” bags are suitable for low flow rates whereas 7” bags are used for high flow rate applications.
Bag filter housings can also be supplied in multi bag configurations to increase the flow capacity, these are usually two, four, six, eight or twelve bag filter housings but other numbers are possible.
Materials of construction of bag filter housings
Stainless Steel is the most common material of construction for bag filter housings due to wide chemical compatibility and strength. For process fluids that are corrosive to Stainless Steel, we can supply bag filter housings in Polypropylene, HDPE and PVDF.
How do Bag Filter Housings Work?
The filter housing is opened
The filter housing is opened by unscrewing the eye nuts and opening the hinged lid.
We offer spring assisted lids with lid locks on larger multi bag filter housings, for ease of opening and operator safety.
Filter bag is installed inside the perforated basket and secured with a bag hold down plate.
Our BFOS Housing Units are compatible with filter bags, elements and baskets!
Liquid enters the housing through the inlet and undergoes filtration
Solid particles are trapped inside the filter bag whilst any filtered liquids pass through and leave through the outlet. These filter bags are usually supported by a perforated basket inside the housing.
Clogged or blocked filter media is replaced
Overtime, the filter bags will become clogged and the bag becomes blocked with contaminants. These filter bags need to be replaced. Once filtration has stopped and the housing has been drained, the dirty filter media inside is replaced.
Clean perforated basket
During this process, you may need to also clean the perforated basket for any dirt or contaminants, most likely in food-grade or hygienic applications that involve strict sanitary regulations.
Types of Bag Filter Housing
Single Bag Filter Housings
These housings are designed to house a single filter bag or element. Single bag housings are effective in Food & Beverage, pharmaceutical and water treatment applications. The BFOS Single Bag Filter Housing is a stainless steel housing that combines high flow rate capability with industrial strength. These highly customisable units can be used with a range of 7” diameter filter bags for fine filtration or with a mesh lined basket for coarse/straining applications.
Multi Bag Filter Housings
These bag filter housings are designed to hold multiple filter bags. These housings are typically used for high flow rate filtration solutions as well as larger scale industrial applications. The multi bag filter housing can hold 4, 6, 8 or 12 filter bags at one time, capable of handling high flow rates in demanding industrial applications. These Stainless Steel units are supplied with a spring assisted hinged lid and swing bolts for operator safety.
Twin Bag Filter Housing (Duty/Duty)
Twin filters use a Duty/Duty configuration and allow for both housings to be used simultaneously, doubling the flow rate of the filtration solution. See our 2BFOS2 twin filter unit for 7” diameter filter bags.
Duplex Bag Housing (Duty/Standby)
Duplex Bag Housings designed in a Duty/Standby configuration allow the operator to change the direction of flow to either of the housings. This is achieved using valves installed on the inlets and outlets or 3 way valves on smaller systems. This is required when applications require continuous filtration without disruption. The 2BFOS2-KVGE (Duty/Standby) Bag Filter Housing comes with switch over valves pre-installed to eliminate process disruption during maintenance. Filtration can be easily switched to standby unit with butterfly valves.
Plastic Bag Filter Housings
These housings are used where Stainless Steel would not be suitable due to the properties of process fluid. Because of their material, they are inert to a large range of common chemicals used in industrial applications, making them efficient in chemical and acid based applications. PORALine BHPP Bag filter housings can be constructed from Polypropylene, HDPE and PVDF which provide excellent chemical resistance in a range of industrial applications. Available in industry standard Size 1 and Size 2.
Sanitary Bag Filter Housings
These bag housings are manufactured to meet the requirements of the Food & Beverage industry. These types of housing are manufactured in higher quality, 316 Stainless Steel which has a higher resistance to corrosion. Industrial polishing of the housings also discourages bacteria and other harmful microorganisms from growing. Our STERALine FBH and FBH Mini are a great option for hygienic bag filtration applications in the food & beverage industry, manufactured in 316 Stainless Steel and available with hygienic connections.
How to Select Which Filter Bag Housing You Should Use?
Correctly Identifying the best bag filter housing for your filtration solution can be difficult, as there are a lot of variables to consider:
Application – The choice of material used in the bag filter housing can be dependent on the liquid being filtered. In the filtration of acids for example, it’s important that the housing and bag filter media is as resistant as possible to the chemicals being filtered in order to mitigate corrosion.
- Temperature – If the filtration process involves high temperatures, then it’s important to consider a housing or filter bag that uses materials that can withstand high temperatures such as Stainless Steel.
- Pressure – The pressure required for the filtration process can affect the specifications of the housing.
- Scale – The scale of the filtration system needed can also affect the housing. Larger projects may require higher flow rates, which may require larger housings or different housing configurations.
Filter Media Selection for Bag Filter Housings
Which filter bag you use is also important to the application it is used for. Siga Filtration’s filter bag housing are available with felt, mesh and oil adsorption filter bags. We offer a wide range of filter bags alongside our housings to provide a complete filtration system.
CLARIBag Filter Bag – Standard sizes and custom options
Filter Bags for Water
Filter Bags for Food & Beverage
Food Grade Bag Filter Units
Siga Filtration offers a variety of filter bag housing options specifically for Food Grade applications, for filtration solutions that require higher flow rates and continuous operation.
STERALine FBH MINI Bag Filter Housing (Size 3 & 4) – Food Grade
