In the distributed gas there are impurities and solid particles which increase in quantity following the laying and welding of new pipes. The equipment, valves, volumetric meters, regulators, and pressure reducers work with mechanical tolerances such that these particles can damage or block them. It is therefore necessary to mount a filter upstream of the distribution, reduction, and measurement devices. The cartridge filters are designed for this service, very versatile, safe, easy to maintain, built in various types, with on-axis connections, with square connections. Produced in various sizes for different flow rates, filters are suitable for filtering natural gas. Or range of filters are of robust construction, and it is possible to make them with characteristic measurements upon customer request to satisfy any need for replacement or new system. Filters are equipped as standard with specific threaded connections for bleeding and for mounting pressure gauges and/or clogging indicators; filters are equipped with unified G Series filter cartridges with a standard filtration degrees of 5 microns.