Types of LPG filters in automotive gas systems
In 4th generation automotive gas systems (sequential gas injection systems in the vapor phase), there are two types of filters:
- LPG liquid phase – Installed in the high-pressure section of automotive gas systems where LPG is in the liquid phase.
- LPG volatile phase Installed in the low-pressure section of automotive gas systems where LPG is in the volatile phase.
LPG liquid phase filters
They filter LPG in the liquid phase (before it changes state to gaseous - volatile). Liquid phase filters are most often part of gas solenoid valves or LPG reducers. Liquid phase filters are also found mounted on the fuel line (LPG) in the high-pressure section of automotive gas systems, in the engine compartment (before the reducer), and on the line between the refueling valve and the LPG tank. This is an additional filter that filters LPG before it reaches the fuel tank.
The filter inserts installed in LPG liquid phase filters most often have a filter media made of paper (filter paper) or, much less frequently, polyester fiber. Additional LPG liquid phase filter inserts (between the refueling valve and the LPG tank) are made of sintered bronze. They are non-replaceable and require only periodic cleaning (washing).
On the multivalve's LPG intake pipe The tank, touching its lower part, features a plastic mesh cover that traps the largest contaminants that may appear in LPG. This is a non-replaceable element.
LPG Liquid Phase Filters - Periodic Replacement of Cartridges
Liquid phase filter cartridges are periodically replaced in accordance with the requirements of automotive LPG system manufacturers, approximately every 20 to 30,000 km.
LPG Vapor Phase Filters
They filter LPG in its vapor phase (after the change of state to gaseous - vaporized, which occurs in the reducer-vaporizer). Gas phase filters are installed on the line (gas hose) in the low-pressure section of the gas system, between the reducer and the LPG pressure and temperature sensor, which is located just before the rail or individual injectors that dose the gas phase of LPG to the intake channels of individual cylinders.
Two basic types of LPG gas phase filters are used. These are non-removable filters (replaced in their entirety along with the housing) and removable filters (with a replaceable filter element), in which only the filter element is replaced. In addition to filtering within the filter element, demountable filters often utilize inertial forces in the swirling motion for central filtration of the heaviest fractions contained in the LPG vapor phase, which, after separation, flow into a special clarifier. Filter elements used in LPG vapor phase filters may have filter media made of paper (filter paper), polyester fiber, glass fiber, or bulprene.
LPG vapor phase filters – Periodic Replacement
Depending on the filter design (removable with a replaceable insert or non-removable), the filter insert or the entire filter is replaced according to the requirements of automotive LPG system manufacturers, approximately every 10 to 15,000 km.
LPG vapor phase filters provide direct protection for the most precise components of 4th generation automotive LPG systems (sequential vapor phase LPG injection systems), such as pressure sensors and gas injectors, against contaminants that may appear in LPG. Sometimes, the LPG vapor phase filter is also the location for the gas pressure and temperature sensor.
Automotive LPG System Inspections
The inspection intervals for automotive LPG systems determine the filter replacement intervals in LPG systems and, in addition to checking the operation of the LPG system, are among the most important maintenance activities. Therefore, servicing the car gas installation, i.e. performing inspections in accordance with the manufacturer's requirements, is a guarantee of its proper operation over a long period of use.