FB™-Series Inertial Bypass Filter

FB™-Series Inertial Bypass Filter


Further Information:

FB-Series bypass filters are inertial separation filters for high particulate load applications. Used upstream of fine particulate filters, FB filters greatly increase the life and performance of particulate and coalescing filters. Flow can be passed through under pressure or pulled through under vacuum. Perma Pure offers a compressed air-driven eductor and a heating system as options.

Inertial Bypass Filter

Large volumes of high-velocity, particulate laden gas pass straight through the filter element (see illustration). Sample is drawn from the bypass flow through a port which is perpendicular to the main flow. Pulled off the bypass stream, the sample is filtered by the mesh or porous filter element. The bulk of the particulate passes directly through the length of the filter element due to its high velocity and inertia, which prevents particulate from being diverted by the pull of the sample outlet port. Any particles that are pulled to the sample outlet are filtered by the element. The high velocity flow also continuously flushes the filter element, reducing pore clogging.
For applications involving a high temperature, wet sample, Perma Pure offers bypass filter heating systems. This involves a simple electrical resistance strip heater mounted in a piece of steel channel. The temperature is controlled with a factory pre-set mechanical thermostat which switches electrical power on and off to maintain the desired setting.

Applications for Perma Pure FB-Series bypass filters can be found in both CEMS and process monitoring applications. In addition to reducing high particulate, these filters can be installed to reduce the response time of analyzers. A pump or vacuum eductor is used to pull the fast bypass sample through the filter thus reducing the response time when the sampling system is located some distance from the sample point. Since analyzers generally only require a sample flow of 1-2 lpm, the time required to pull the sample from the sample point to the analyzer would be excessively long without this fast bypass loop. This increases the life of conditioning systems. By virtue of its design the Perma Pure Bypass Filter, which is sometimes called an inertial filter, serves to eliminate large amounts of particulate and tends to be self cleaning.


FB-Series filters are available in two models: FB-625 and FB-1000. Flow rating for the filters is dependent on the particulate level of the sample. In general the FB-625 Series filters are suitable for sample flows of up to 10 liters per minute while the FB-1000 Series filters can handle higher flows.

Model Number A B C D E
FB-625-SS-6 8.125″ 6.265″ 4.625″ 0.875″ 0.875″
FB-625-SS-12 14″ 12.5″ 9.5″ 0.875″ 0.875″
FB-1000-SS-6 8.125″ 6.625″ 3.625″ 1.125″ 0.875″
FB-1000-SS-12 14.25″ 12.75″ 9.75″ 1.125″ 0.875″


Model Number Inlet/Bypass Port Outlet Port Shell Vol. Pmax (psig) Hex
FB-625-SS-6 1/4″ 1/8″ 40 mL 1000 3/4″
FB-625-SS-12 1/4″ 1/8″ 80 mL 1000 3/4″
FB-1000-SS-6 1/4″ or 1/2″ 1/4″ or 3/8″ 45 mL 750 1″
FB-1000-SS-12 1/4″ or 1/2″ 3/8″ 90 mL 750 1″


All connections are female NPT

All seals are viton

Element Description Porosity Tmax
S Sintered stainless steel 10 microns 150°C
M40 (1000 series only) Wire mesh stainless steel element, 40 mesh 400 microns 150°C
M100 Wire mesh stainless steel element, 100 mesh 150 microns 150°C
M200 Wire mesh stainless steel element, 200 mesh

Accessories for Sample Conditioning

Ammonia Scrubber

Inertial Bypass Filters

Coalescing &
Particulate Filters

selector-AS-series selector-FB-series selector-ff-series

Heatless Dryers

Nafion-Desiccant Dryers

selector-hd-series selector-dm-dryer

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Baldwin Dilution and Extraction Probes



Sample Gas Dryers, Humidifiers and Conditioning Systems Product Portfolio

Gas Sample Dryers
Perma Pure offers Nafion® based tube and shell style dryers (requiring a dry counterflow gas) and dryers open to atmosphere for a wide range of flow rates up to 40 lpm.

Medical Breath Dryers and Breath Sampling Lines
Perma Pure offers Nafion® based breath dryers and standard breath gas sampling lines made from PE, PVC, or coextruded PE/PVC, available with a wide range of connection interfaces.

FC-FamilyGas Humidifiers

Where applications require a gas stream to be humidified. Perma Pure’s  Nafion® based Gas humidifiers are the ideal method using either gas or water to provide the humidification.

  • MH-Series Humidifiers  – Single tube Nafion® humidifier for flow rates up to 10 l/m using DI water as the humidification source
  • FC-Series Humidifiers – Multiple tube Nafion® dryer for flow rates up to 10,000 l/m. This product line was developed for fuel cell humidification applications in either gas to gas or water to gas modes.
MiniGASS-2812Nafion® Based Sample Conditioning Systems
Perma Pure’s Nafion®–based Sample Conditioning Systems’ advantage is the ability to remove moisture from the sample stream in the vapor phase, preserving the components to be analyzed – particularly water soluble gases such as SO2 and NOx among others.


Baldwin Sample Gas Coolers

Perma Pure and Baldwin Filters, Scrubbers and Accessories

  • AS Series Ammonia Scrubber
  • FB Series Inertial Bypass Filter
  • FF 250 Series Filters
  • HD Series Heatless Dryers
  • DM Series Desiccant Dryers
Baldwin Sample Conditioning Systems and Other Products


Baldwin Dilution and Extraction Probes