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This article serves as a general overview of all the filters produced by the respiratory protection branch of Pirelli (currently named DPI Sèkur), from the late '20s up to current production.
Important note on the nomenclature: Pirelli filters follow a simple nomenclature: save for exceptions, there is always a name that defines the use, followed by a number that refers more specifically to the size (with higher numbers for larger filters). The number is then followed by a string of letters and numbers which define its protection type. The meaning of said string can be viewed some times on the filter itself and other times from a catalogue.
Dirin[]
Dirin filters are essentially threaded cartridges that are usually small enough to be fit directly onto the facepiece. Most are made of aluminium, but some current ones are instead plastic. The name "Dirin" is followed by a number, which can go from 230 up to 600, and then the type of protection provided.
Late '20s-early '30s []
The earliest Dirin filters were usually openable and sported a 30mm thread. They can be distinguished by their small thread, the two ridges running around the side and the feature threaded bottom of the filter. An almost identical filter would be provided for the P.C. 30.
1932-late '30s[]
During 1932-1933 a new design of Dirin was put in production, with a new shape and new features. Firstly, the threaded bottom was done away with, as it was no longer seen as optimal. The inlet was provided with a rubber plug attached to a string which could be removed and placed back in at any moment, a feature that would be kept for the following 70 years. The shape didn't change much from one filter to another, some filters had a recess going around the cylinder body, while others didn't (the smaller ones). The earliest filters of this type were provided with a 30mm thread, while later models would sport a 40mm DIN one. Various masks had filters derived from this design.
1935-'80s[]
At around 1935, new designs started to be sold alongside the former types. One new shape, in particular, the same used with the T.35 filters and its derivatives, would then take over and become the standard filter shape for the following years, even until now. In general, the designs didn't differ much from the previous types: they were just slightly wider in some sections and didn't have any recess. This design is also the most varied, with the smallest being the Dirin 250, and the largest being the 600, all sharing the general design. The shape didn't change much over the years, with only occasional minor improvements.
During the '70s circa, the smallest filters, like the Dirin 300, started being made in a cylindrical shape, with various holes on the bottom covered by a single rubber plug as wide as the bottom of the filter.
'80s-now[]
The last generation saw the arrival of plastic filters which, lighter and generally cheaper, over the years replaced most of the aluminium filters. Plastic filters are cylindrical, with occasionally a protruding ridge between the layers.
The only two filters that are still made in aluminium and with a T.35-like shape are the Dirin 500 and Dirin 530; the plug is no longer attached to a string, and the bottom is made of plastic.
Tubin[]
Tubin filters are large canisters that are connected through a hose to the facepiece. These filters were made of aluminium, and are currently out of production. The name "Tubin" is followed by a number (usually 1200 or 1500) and then the type of protection provided. Universal-use Tubin filters are called Turnivercio.
Late '20s-late '30s[]
The earliest type of Tubin filter didn't differ much from the flat filter used with the Penna, they were used for longer periods than Dirin filters and were carried either in a cage carrier or a carrier case. Most, if not all, were Tubin 1500. The plug system different from later types, as it used two fixed caps on a hinge that the user could move to open or close the inlets.
Late '30s-until ceased production[]
During the late '30s-'40s a new, smaller, type of Tubin was produced (usually Tubin 1200 or 1500). It was carried most of the times with a cage carrier. It was used until the early '80s.
Other filters[]
The smallest filters are often installed using proprietary threadings or are fixed with other methods. The nomenclature is usually "filtro" (filter) followed by a number and the type of protection provided.
Gallery[]
Advertisements, filter selections and types.
1933 Pirelli filters' catalogue[]
Cold-War era catalogue[]
This filter section lacks most pages
