PBH Bag Filter Housing Sizing Guide

Sizing guide for PBH Bag Filter Housing and BP & BN Series Filter Bags

This sizing guide provides information for the initial sizing and selection of PBH Bag Filter Housing and BP & BN Series filter Bags


Where to use?

Removal of coarse and fine particles
Protection of fine filters (e.g. fine filter cartridges)
Straining applications
CNC machine coolant
Food & beverage


Which filter bag material to use?  

Polypropylene felt for general reduction of particulates. Available micron ratings 1, 5, 10, 25, 50, 100, 200
Nylon mesh for removing particulates of a specific size or straining applications. Available micron ratings 50, 100, 200, 400, 600

Typical water flow rates:

Filter size
Flow rate
PBH Size 10 Housing
50 lpm (3 m3/h)
PBH Size 20 Housing
100 lpm (6 m3/h)
* With 25 micron PP felt bags
* * Please note that flow rates may vary depending on application – i.e. dirt load, viscosity, micron rating etc.

What is the micron rating of various particles?

A micron is a unit of measure and equals one thousandth of a millimetre.
1mm = 1000 microns (micrometer)
1 inch = 24,500 microns (imcrometer)
Paint pigments
0.1 – 5 micron
Corn starch
0.1 – 10 micron
Face powder
0.1 – 30 micron
Bacteria (Pharmaceutical applications)
0.2 micron
Bacteria (Food applications, beer)
0.45 or 0.65 micron
Fine clay
0.5 – 1 micron
Copier toner
0.5 – 15 micron
Coal dust
1 – 100 micron
Yeast (food applications, beer)
3 – 40 micron (average)
Silt, fine
8 – 13 micron
Silt, coarse
37 micron
5 – 400 micron
25 – 40 micron
Sand, very fine
60 micron
Sand, fine
125 – 250 micron
Beach sand
500 – 700 micron
Coffee, espresso
200 – 500 micron

The information in this guide is accurate to the best of our knowledge and provided for preliminary selection. It is your responsibility to determine if additional testing or information is required and if this product is fit for a particular purpose. Siga Filtration will not be responsible for any damages resulting from the use of this information.  


Filter bags & filter socks

Our bag filtration systems are widely used for the reduction of sediment from industrial and food applications due to their high flow rate capability, easy maintenance, and rugged design. Siga Filtration can offer filter bags for general particulate removal and high-efficiency removal of particulates. For high flow rate applications, Siga Filtration can offer multi-bag filter housings that can handle flow rates of up to 400 m3/h. All standard filter bags are supplied with integrated handles for easy removal from filter housings. Filter bags are available with removal ratings from 0.5 – 1800 µm.


Know which filter bag to use? Skip to our filter bag product pages.


Filter bag material selection
Siga Filtration can supply filter socks in Polypropylene felt, Polyester felt, and Nylon mesh. Polypropylene felt has wide chemical compatibility and is suitable for most industrial, water and chemical applications up to an operating temperature of 80°C.
Polyester felt filter socks have a high-temperature resistance (up to 120°C with SS or Polyester ring). These filter bags also provide excellent resistance against hydrocarbons and are a material of choice for the filtration and polishing of gasoline, diesel, biodiesel, and other fuels.
Both Polyester and Polypropylene felt filter bags provide clarification of particles. These filter bags also provide removal of gelatinous or deformable particles due to the depth of the filter medium.
Nylon monofilament mesh filter bags remove particles by sieving and are used for the classification of particles.
Filter bag temperature ratings
Polypropylene felt 80°C
Polyester felt 120°C
Nylon monofilament mesh 90°C
* Temperature ratings depend on application and process fluid
Filter bags sizes
Our filter socks are available in the following industry-standard sizes:
Bag Size 1 – 7” x 16” approx. with a moulded plastic collar, stainless steel ring, drawstring or no collar
Bag Size 2 – 7” x 32” approx. with a moulded plastic collar, stainless steel ring, drawstring or no collar
Bag Size 3 – 4” x 8.8” approx. with a moulded plastic collar, stainless steel ring, drawstring or no collar
Bag size 4 – 4” x 15” approx. with a moulded plastic collar, stainless steel ring, drawstring or no collar
Custom size – These filter bags can be manufactured to customer specifications and sizes.


Filter bag flow rates
Our filter bags provide a high flow rate capability combined with excellent dirt holding capacity. Flow rates depend on many factors like application, particulate concentration, micron rating, and viscosity. A general guide to flow rates is provided below for water with 10 micron felt type filter bag.
Size 1 bags – 20 m3/h
Size 2 bags – 40 m3/h
Size 3 bags – 6 m3/h
Size 4 bags – 12 m3/h
Filter bag applications
Siga filtration can supply filter bags for the following applications and many more:
Automotive – Filtration of paints, parts washing and cutting fluids
Chemical – Filtration of acids, alkalis, solvents
Food & beverage – Beer, edible oils, syrups, honey, kombucha, water
Metalworking – Filtration of cutting fluids and parts cleaning fluids
Paint – Removal of agglomerates, particulates
Resins, inks, coatings – Dispersions, ink, resins
Water – Sediment removal, carbon fines, resin fines
HVAC – Removal of sediment, rust and calcium deposits from LTHW, CHW circuits
Food grade filter bags
Our BREWBag filter bags are constructed from food-grade materials and provide an excellent particulate reduction solution for various production stages in the food & beverage industry. These filter bags are available in micron ratings from 0.5 – 1800 µm.
Custom sizes
In addition to standard sizes, we can supply filter bags in customer specified lengths and diameters.
Extended life and high-efficiency filter bags
Extended life filter bags feature a thicker media for increased particle retention and filter life. These are ideal for applications where longer filter life is required to reduce maintenance demand. Our high-efficiency filter socks can provide greater than 99% removal of particulates in applications that require an extremely low particulate count.
Filter bag micron ratings
Polypropylene & Polyester felt filter socks – 0.5, 1, 5, 10, 25, 50, 100, 200 µm
Nylon monofilament mesh filter socks – 1, 5, 10, 25, 50, 75, 100, 125, 150, 200, 250, 300, 400, 500, 600, 800, 1000, 1200, 1800 µm
Filter bag chemical compatibility
Our standard filter bags provide broad chemical compatibility in industrial and chemical applications.
Polypropylene felt bags – Acids, alkalis, organic solvents, alcohols, oxidisers
Polyester felt bags – Hydrocarbons, alcohols, acids, solvents
Nylon monofilament mesh bags – Solvents
* Chemical resistance depends on operating temperature, process fluid, and application. The material should be soak tested prior to use. 

Inline filters – Industrial & Food Grade

Inline filters provide an easy installation solution with minimum pipe modifications. Siga Filtration can offer compact inline filters with a flow rate capability of 0.5 – 300 m3/h. Inline filters can be supplied with Polypropylene filter elements, stainless steel elements, or cleanable stainless steel baskets. These filers usually come with inline connections for easy installation. Inline filters are widely used in the process industry and feature a compact design to allow for installation where space is limited or a filter needs to be added to a process retrospectively. Large basket type inline filters can be supplied for use in applications where a high flow rate is required, these are common for applications in HVAC, pump & valve protection, testing rigs, and transfer between tanks.

Flow rate capability
Siga Filtration can supply inline filters for flow rates from 0.5 m3/h to 300 m3/h. These can be supplied in simplex or duplex arrangement.
Our inline filters are available in plastic, stainless steel or cast iron depending on the application and can be used for the filtration of water, chemicals, oils, and food products.
Food grade inline filters 
STERALine PBT filter housings are constructed from 316L stainless steel to food-grade specifications and come with FDA approved gaskets. In the food industry, these inline filters can be installed at the end of the production line for removing visible particulates, yeast, cryptosporidium, bacteria, and spoilage organisms. Sediment removal grades can also be used to capture particulates from feed water.
Industrial Inline water filters can be used for coarse and fine filtration depending on the application. At the end of the production line, these are used for polishing applications. If installed upstream, these filters provide excellent reduction of particulates from feed or makeup water and provide ongoing removal of particulates. These can be used with polypropylene plastic filters, with a stainless steel mesh element or a cleanable basket. Our inline water filters can be supplied in cost-effective Polypropylene or industrial grade stainless steel. When used with carbon filters, these can remove chlorine, chloramine, colour, and odour from water. Standard connections are 1” on stainless steel filters and ¾” or 1” on plastic filters.


SF-IL series inline filters come with a bolted closure and a cleanable and removal mesh-lined stainless steel basket. These are suitable for high flow rate applications and feature a fully welded stainless steel construction. SF-IL series inline filters are available with 1” – 8” flanges, other connections and sizes can be manufactured on request. All models can be supplied with a fully assembled differential pressure gauge to indicate a blocked filter. 
Inline filters for beer, vodka, whisky, beverages, food products
Our STERALine PBT inline cartridge filter housings in 316 stainless steel come with sanitary tri-clamp, RJT, SMS, DIN11851 connections and are constructed from food-grade materials. These can be used with polymeric filter elements and provide a reduction of particulates down to 0.2 micron. The connections are inline which can either be used with fixed pipework or flexible hoses. The top dome can be removed to fully expose the elements during maintenance. 
Inline filters for chemicals
1FU inline filter housing can be supplied with a mesh element for coarse removal of particulates. The mesh elements are constructed from stainless steel and available in micron ratings from 50 – 3000 micron. These inline filters can be supplied with PTFE gaskets for corrosive applications. Stainless steel mesh elements can be cleaned and reused.
Inline filters for CNC machine coolant
1FU inline filter housings provide a compact particulate removal solution and keep the cutting fluid in good health. These can be used with acuraMultiflow filter elements rated from 1 to 200 micron.
Inline filters for raw material transfers
F-SF basket inline filters have been specially designed to filter sediment during tank transfers, these are suitable for both food & industrial applications and can be supplied with threaded, cam locks, or dairy connections. Filtering raw material at the point of entry avoids particulates entering the process.
Duplex inline filters
Our duplex inline basket filters provide a solution for continuous flow. These are available in cast iron or stainless steel in a range of basket mesh ratings. These can be supplied with a DP gauge to indicate a blocked filter.

Sidestream Filters for an Award Winning Developer

Siga Filtration win a new Sidestream Filtration job for the protection of LTHW circuit in a new apartment build by award-winning developers.


We supplied our FLOWStream FLS-5 sidestream filter system complete with a pump and blocked filter indication. This unit will remove suspended impurities and contaminants from recirculating hot water and help keep the system in good health. FLOWStream FLS will also allow for the water treatment to work more efficiently by removing particulates. 


Find out more about FLOWStream FLS Series Sidestream Filters
See our Sidestream Filtration Solutions

Airbus Chiller Upgrade – Siga Filtration wins new sidestream filter project

Airbus Defence and Space teams focus on the design and manufacture of advanced satellites and systems for telecommunications, earth observation, and navigation and science programmes. They also support the UK’s military satellite communications services to the UK armed forces, including mobile voice, video, Internet and broadcast communications.


We were approached by design contractors for chiller upgrade project to offer our filters for Sidestream Filtration of Chilled Water Circuit (CHW). This was a large system with a flow rate requirement of 50m3/hr.
Filters were required to remove particulates and avoid build-up of solids in recirculating water which can cause heat exchanger fouling and render chemical water treatment ineffective.
Siga Filtration offered Duplex Bag Filter Housing System 2BFOS2 in duty/duty arrangement to cope with high flow rate demands. This unit was supplied with a fully assembled differential pressure gauge to provide a visual indication of blocked filters.


Benefits of using sidestream filters by Siga Filtration:
Siga Filtration provides filtration solutions for chilled water (CHW), low temperature hot water (LTHW) and medium temperature hot water (MTHW) circuits.
1) No moving parts; easy to maintain and use
2) No spares requirements other than gaskets
3) Highly cost effective compared to more complex filtration systems
4) Designed to target particulates, dirt and rust
5) Track record of successful installations
Find out more about FLOWStream FLS Series Sidestream Filters
See our Sidestream Filtration Solutions

Contamination in CNC Coolant Systems & Filtration Solutions

All CNC coolant systems left unfiltered will eventually develop bugs and accumulate chips and particulate from the work surfaces. These impurities can quickly contaminate the coolant causing costly disruptions and component failure.


The concentration of these contaminants will continue to increase over time unless it is filtered out or removed by other means like coolant replacement and sump cleaning. This also has a detrimental affect on the quality of work, results in poor repeatability and also clogs up or reduces flow capacity of your cooling system. Nozzles and valves can block up. Nozzles can also get damaged due to abrasive affect of chips recirculating in coolant.
Considering the cost of tools, nozzles, valves, imperfect or rejected jobs and new coolant, it quickly becomes apparent that a correctly designed filtration system could provide a significant cost saving.
Installing a filtration system for your CNC coolant is both easy and economical in the long run. Our filter cartridge and bag filter housings provide a low maintenance solution. Filter, once installed, requires maintenance only when the filter cartridge or bag has clogged up with impurities and requires replacement.
CNC coolant filters are available in a range of coarse and fine grades. We recommend starting off with a 25 or 50 micron filter and then gradually moving down to suit your individual requirements. Filtration units can also be installed in series where a coarse prefilter or strainer would remove larger chips and particulates and protect the downstream fine filters. These are extremely versatile units and can also be added in parallel should your coolant filtration requirements increase in future.
We recommend installing a pressure gauge upstream and downstream of the coolant filter to measure differential pressure which is the only reliable method to correctly indicate filter changeout. All our filter housings can be supplied with a differential pressure gauge mounted on the unit with an easy to read coloured dial. 


Download Machine Tool Coolant Application Guide

Siga Filtration at CHEMUK 2019

Siga Filtration was successfully represented at CHEMUK, a new UK Chemical Industries Exhibition, bringing together all key layers of the UK’s Chemical & Chemical Products industries.

In two days we saw many customers and suppliers at our stand and we enjoyed the chance to present some innovative filtration products from our wide product range. We showcased our basket filters and new acuraControl unit for filter monitoring which generated a lot of interest from visitors and customers.