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In-Line Deflagration Flame Arrester concentric design, bidirectional

  • build up of adhesive materials is prevented by the smooth surfaces
  • application especially for corrosive and polymerizing media
  • minimum number of FLAMEFILTER® discs due to patented design
  • service-friendly design
  • the modular design enables each individual FLAMEFILTER® to be replaced
  • bidirectional operation as well as any direction of flow
  • installation of temperature sensors is possible
  • less soiling of the device lowers service, operating and life-cycle costs
  • minimum pressure loss and associated low operating and life-cycle costs

Function and Description

The in-line deflagration flame arresters type PROTEGO® FA-I-PTFE are the latest generation of flame arresters and are distinguished by their unique resistance to adhesive and corrosive media. The use of fluoroplastics as a high-tech housing coating and as solid material for the flame arrester element is unique throughout the world.

When installing the deflagration flame arrester make sure that the distance between potential ignition sources and the location of the installed device, the L/D ratio (pipe length/pipe diameter), does not exceed the value of 50.

The deflagration flame arrester is symmetrical and offers bidirectional flame transmission protection. The arrester essentially consists of two coated housing parts (1) and the PROTEGO® flame arrester unit (2) in the center. The PROTEGO® flame arrester unit is modular and consists of several FLAMEFILTER® discs (3) and spacers firmly held in a FLAMEFILTER® casing. The number of PTFE-FLAMEFILTER® discs and their gap size depends on the arrester‘s conditions of use.

The deflagration flame arrester PROTEGO® FA-I-PTFE can be used for explosion group IIA (NEC group D). The standard design is approved at an operating temperature up to +60°C / 140°F. The maximum allowable operating pressure depends on nominal diameter (DN) and nominal size (NG) and amounts to a maximum of 1.6 bar / 23.2 psi absolute (for DN 100 / 4” and DN 150 / 6” see table 3).

Type-approved according to ATEX Directive 94/9/EC and EN ISO 16852 as well as other international standards.


To select series and nominal size (DN) - nominal width (NG) combination, please use the flow capacity chart on the following page

DN50 / 2"80 / 3"100 / 4"150 / 6"
NG150 / 6"150 / 6"200 / 8"300 / 12"
a287 / 11.30287 / 11.30342 / 13.46447 / 17.60
b380 / 14.96380 / 14.96468 / 18.43612 / 24.09
c430 / 16.93430 / 16.93480 / 18.90530 / 20.87
Dimensions in mm / inches

Material for housing

Design A
HousingSteel with an ECTFE coating
Flame arrester unitA, B, C
Special materials upon request

Material combinations of flame arrester unit

FLAMEFILTER® cageSteel with an ECTFE coatingHastelloyStainless Steel
Spider ringsSteel with an ECTFE coatingHastelloyStainless Steel
* electrically conductive Special materials upon request.

Selection of explosion group

MESGExpl. Gr. (IEC / CEN)Gas Group (NEC)
> 0.90 mmIIAD
Special approvals upon request

Selection of max. operating pressure

DN50 / 2"80 / 3"100 / 4"150 / 6"
NG150 / 6"150 / 6"200 / 8"300 / 12"
Pmax1.6 / 23.21.6 / 23.31.2 / 17.41.2 / 17.4
Pmax = in bar / psi absolut, higher operating pressure upon request

Specification of max. operating temperature

≤ 60°C / 140°FTmaximum allowable operating temperature in °C
higher operating temperatures upon request

Flange connection type

EN 1092-1; Form B1
ASME B16.5 CL 150 R.F.
other connections upon request

Design Types and Specifications

There are three different designs:

Basic in-line deflagration flame arrester


In-line deflagration flame arrester with integrated temperature sensor* as additional protection against short-time burning from one side


In-line deflagration flame arrester with two integrated temperature sensors* for additional protection against short-time burning from both sides


Additional special devices available upon request
*Resistance thermometer for device group II, category (1) 2 (GII cat. (1) 2)

Flow Capacity Chart

The flow capacity charts have been determined with a calibrated and TÜV certified flow capacity test rig. Volume flow V in (m³/h) and CFH refer to the standard reference conditions of air ISO 6358 (20°C, 1bar). For conversion to other densities and temperatures refer to Sec. 1: “Technical Fundamentals”.