Cold filter plugging point

The term Filtrierbarkeitsgrenze or Cold Filter Plugging Point (CFPP; officially, according to DIN Temperature limit of filterability ) denotes a cold property of diesel fuels and heating oil EL ( extra light ). It is the temperature in degrees Celsius, at a test filter clogged under defined conditions failed (n- ) paraffins. In this method, the sample is cooled at a constant rate and transported here at defined intervals by a test filter. Before reaching the Filtrierbarkeitsgrenze already formed during the so-called cloud point ( CP) crystals, but still fit through the filter. Only if the crystals are too large, clogging of the filters. The Filtrierbarkeitsgrenze unadditivierter goods ( see below ) is generally just below the cloud point. If the spread between the cloud point and Filtrierbarkeitsgrenze to be increased ( for instance in winter diesel roughly 13 K), additives must be used.

Diesel fuel

The Filtrierbarkeitsgrenze is important for the reliability of diesel vehicles in winter. At low temperatures in the fuel drop out (n- ) paraffins contained and form wax crystals clog the fuel filter of the vehicle. One can influence the Filtrierbarkeitsgrenze by four methods: by reducing the cloud point / the Filtrierbarkeitsgrenze in the basic goods ( the final boiling point of the heaviest component, the heavy gas oil is reduced, and the paraffins remain in the atmospheric residue ), due to increased fuel blending and additives. Further, the cetane number can be carried out by removal of the n-alkanes from the mixture. This can be achieved through molecular sieves.

The lowering of the final boiling point (SE ) reduced cloud point and Filtrierbarkeitsgrenze alike. The desired Filtrierbarkeitsgrenze of about -12 ° C to -20 ° C can not be achieved by the sole reduction of the final boiling point, as the subsequent high vacuum system that breaks down the atmospheric residue into its components, the vacuum could not keep.

The increased fuel admixture reduced cloud point and Filtrierbarkeitsgrenze also alike. Again, the desired Filtrierbarkeitsgrenze by merely mixing of kerosene can not be achieved, since more fuel would have to be added, as originally diesel was available, that would hurt other specifications. Furthermore, the use of kerosene (as a base fabric for aviation fuel production ) under normal price conditions too expensive. Thus, the use of additives has also an economic aspect.

Through additives crystal growth can be modified (many small crystals instead of a few large ) that the crystals the fuel filter can continue to happen and the Filtrierbarkeitsgrenze shifts in the colder area. Other additives ensure that the crystals do not settle on the ground, but equally remain in limbo ( Wax Antisettling additives; WASA ). A diesel fuel having a Filtrierbarkeitsgrenze below -20 ° C is referred to as a winter diesel fuel. It may happen, however, that summer diesel or transitional goods contains additives. The criterion " additives " therefore can not be used to define winter diesel.

Since the Filtrierbarkeitsgrenze by additives can reduce only to a limited extent, is lowered for winter diesel, the cloud point at about -7 ° C (reduction of the final boiling point and / or kerosene), and by the additive Filtrierbarkeitsgrenze is then reduced to -20 ° C. Brand manufacturers specify therefore the cloud point for their fuel.

For diesel, the Filtrierbarkeitsgrenze in DIN EN 590 set depending on the season ( summer, winter and transitional goods).

The reliability of the CFPP is criticized as weak - the ADAC had commercial winter diesel subjected to a cold test. Although all diesel places the laboratory test according to DIN further exceeded, already failed real diesel engines under DIN specification in the cold chamber. In particular, the CFPP value of the different mineral types were not in direct correlation to the actual observed cold starting of diesel engines - therefore it is proposed to build a new test standard.

Extra light heating oil

The DIN 51603 Part 1 regulates for extra light heating the Filtrierbarkeitsgrenze depending on the cloud point:

• Up to -12 ° C, at a CP of 3 ° C
• Maximum -11 ° C, at a CP from 2 ° C
• Than -10 ° C, at a CP < 1 ° C.

Extra light heating oil for the cold properties play an important role in the storage tank at the refinery, transportation by tanker as well as in outdoor storage for customers. Without compliance with the Filtrierbarkeitsgrenze It will cause failure of the burner system are used in outdoor storage or crystallized paraffins with the tanker supplied already, cause interference.