BOLLFILTER Duplex Type BFD-C/P DBB: coalescer and particle gas filter with Double Block and Bleed

A special design duplex filter for separating solids and/or aerosols (liquid content) from gases using a patented double block and bleed main transfer valve. This is intended for applications using high pressures and/or dangerous gas compositions, to ensure maximum operator safety.
Flange Connection
¾” – 8” or DN 20 – DN 200
Filter element
Fiberglass/stainless steel disposable cartridges*

Option available for preliminary separation using demister, cyclone, or cyclone demister all within the same housing
Grade of filtration
0,1 µm - 250 µm
Operating pressure
>500 bar (size and temperature dependent)
Filter housing
- carbon steel (St 45-8 / A106B)
- stainless steel (1.4404 / 316L)
- non-welded
General Accessories and Special Equipment
1.) Connecting elements
Flexible connection possibilities
e.g., flanged, NPT, weld-on ends, ball valves, needle valves

2.) Instruments
Differential pressure connections such as optical and optical/electrical differential pressure measurement systems

3.) Materials
Filters available on request in Duplex or Super Duplex

4.) Optional equipment
Cover lifting/pivoting mechanism
Cover safety device
Special accessories for gas filtering
Pre-separator for liquid reduction / cyclone and cyclone demister

In addition to standard, filters also available in Duplex and Superduplex (on request)

Liquid level switches

Magnetic level indicator

Bulls Eyes

Adaptable fluid reservoir for saving the separated fluid
BOLLFILTER Duplex Type BFD-C/P DBB: coalescer and particle gas filter with Double Block and Bleed

The BOLLFILTER duplex filter type BFD-C/P DBB consists of two filter chambers. One filter chamber is in operation while the other is being cleaned or on stand-by.

If contamination exceeds a tolerance threshold, the unit can switch over to the clean filter side - by means of the Double Block and Bleed method - without any pulse pressure. The contaminated filter element is then cleaned while operation continues.

Double Block and Bleed (DBB) technology increases the system safety having an additional isolation as fail safe.

The downstream valve is first closed, followed by the upstream valve. When the primary isolation valve is closed, the media flow will have stopped. Secondary isolation can be closed and immediate trapped can be drained though the vent port.


High End Gas coalescence filtration &#9654; Double Block and Bleed Filter &#9654; Switch-lever safety interlock mechanism &#10003; Proven leakage rates of individual seals within the ball valve < 1,37 x 10-4 mbar l/s
BOLLFILTER Duplex Type BFD-C Double Block and Bleed
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Jens Debel-Hasløv, Sales Manager BOLLFILTER Nordic
Jens Debel-Hasløv

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