TO Rome there was one strong explosion To a petrol and LPG distributor in via dei Gordiani 32, in the east of the city: the accident caused a fire from which a dense column of smoke was raised, visible from different points of the capital.
According to the Ansa, the explosion would have been caused by the “detachment of a pump of a cistern», Which fed the distribution system, with the closing cap of the driver who was found about 40 meters away from the distributor. In reality, the actual dynamics of the accident are not yet completely clear: according to what reported by the firefighters, however, there seem to have been two different explosions.
But, in any case, how does a LPG distribution system and what are these pumps and cisterns?
As a LPG distributor is made
In general, the LPG distributor is a machine used for filling Liquefied oil gas (LPG), That is, a mixture of hydrocarbons gases, mainly composed of Propano and Butano, which is used as fuel for both heating systems and vehicles, as an alternative to diesel or petrol.
The elements of which the service station is composed are listed in the technical fire prevention rule contained in Presidential Decree 340/03 and, specifically, are:
- one or two fixed tanks which contain the LPG to be paid to the refueling cars;
- a filling to which the truck is connected;
- pumps used for disbursement of LPGs to motor vehicles;
- pump and/or compressor used for filling fixed tanks for discharge of the product from the tanker;
- one or more distribution devices to simple or double delivery to supply cars;
- premises intended for ancillary services (Office, rooms for sale, warehouses, toilets, washing systems, workshop without using free flames, refreshment seats, manager of the manager etc.).
How a LPG distributor works
In distributors for LPG, this gas is preserved in liquid form within a series of storage tanks. In general, it is possible to maintain the liquid liquid -state oil gas because they are subjected to strong pressure (usually between 5 and 10 bars). This mode of conservation, among other things, is not accidental: the gas is stored in liquid form to be able to transport it and store more easily. In any case, the tanks are built specifically to support these strong pressures and can support up to 25 bar.
Just to ensure greater safety, the tanks of LPG distributors are often underground, and therefore not visible from the outside: in any case, the Italian legislation establishes a series of security measures Rather severe, with the aim of promoting high safety standards for the use of underground LPG tanks and thus reducing the risk of accidents or damage.
Considering then that the volume of the LPG varies according to the temperature, in Italy the cylinders are filled approximately 80%, so as to maintain a balance between liquid and gaseous part.
The transfer of LPG
When the LPG is taken from the tank, however, it comes vaporized: this means that, in the disbursement, The LPG returns to the gaseous state. In order to carry out this work, pumps are often necessary, which push liquid LPG from the tank of the cistern to that of the machine, ensuring that the flow is constant and that the gas arrives correctly to the point of delivery. Generally, the pumps used in LPG distributors are of two types:
- piston pumps: they are composed of a cylinder inside which there is a piston which, moving from top to bottom, creates a suction system that is able to withdraw the liquid and flow it towards the delivery point.
- gear pumps: they consist of two equal tooth wheels and contact each other. In this case, the gears revolve in opposite directions, making sure that the liquid fills the space between the teeth and be conducted towards the delivery point.
In the phases of refueling of the service stations, the liquid contained in the truck is downloaded in the station tank through a pump which allows the product discharge into the desired quantities. The pump allows you to withdraw the LPG from the bottom of the tanker and move it, through the connection pipes, up to the tank.
The connection pipes are present in a fixed way in the service station and connect with sleeves very resistant to those of the carbootte when the exhaust must take place. On the pipes, both on the side of the service station and on the side of the carboot, they are present valves, which are responsible for managing the product passage both in conditions of normal operations and in emergency conditions. In fact, the fire prevention legislation provides for a remote command So that you can close them in emergency conditions. In case of fire, then, their activation may be both manual is automatic.
