Why can’t I refuel when unloading the oil?

At present, many gas stations refuel cars and unload the oil at the same time, which can improve the efficiency of gas stations. In fact, during the process of refueling and unloading the oil at gas stations, the risk of static electricity in the oil will increase.

Why is it not recommended to refuel at a gas station when unloading? This article will tell you.

gas station


1、The effect of gas station facilities on static electricity

a) The cleaning cycle of the gas station tank is generally 3~5 years.

The bottom of the tank makes it easy to accumulate impurities such as water with a higher density than oil, and sometimes even impurities such as rust or gravel will be deposited.

b) The tank relates to a metal pipeline between the tank and the tanker, the length of which varies from a few meters to tens of meters.

The oil will have a certain amount of electrostatic easing in the pipeline, but the elbow present on the pipeline will cause a change in the flow condition of the oil, resulting in the generation of static electricity.

c) To ensure the quality of the oil, the dispenser is generally installed with a fine filter with a pore size of tens of microns.

This can filter out impurities in the oil, and small pore-size filters can easily lead to the generation of static electricity.

d) The hose of the refueling gun is generally made of insulating rubber.

The length of the hose is about 4 meters, and when the oil passes through the insulated rubber pipe, static electricity is generated.


2、Static electricity generation during unloading

In the process of unloading the oil tanker, there are mainly the following electrostatic energizing methods in the oil tank: oil flow energizing, oil agitation energizing, impurity sedimentation electrolysis, etc.

Oil flow electrification refers to the accumulation of static electricity after the friction between the oil and the unloading pipe and the oil pipeline during the unloading process of the tanker.

The factors affecting the flow of oil mainly include pipeline material, transportation speed, etc.

Oil agitation and electrification mainly refer to the fact that after the oil enters the tank from the unloading port, it drives the oil movement in the tank and generates an electric charge, especially after the water impurities at the bottom are aroused, the oil movement will produce a large amount of static electricity.

Impurity sedimentation and electrolysis mainly refer to the separation of impurities in the oil from the oil during the sedimentation process and generate static electricity.

The static electricity generated by the unloading of the oil in the oil tank is not fully alleviated through the tank and the oil pipeline. It is sprayed from the fuel nozzle, resulting in an increase in the electrostatic charge of the oil at the outlet of the oil nozzle.

oil nozzl

3、Static electricity is generated during refueling

The unloading process caused impurities to be stirred up at the bottom of the tank.

Oil-containing impurities generate more static electricity after passing through pipelines, dispenser filters, and insulating hoses.

The main component of impurities in the tank is water, and the relevant tests show that when the water content in the oil is 1% ~ 6%, it is easy to generate static electricity and cause static electricity accidents during the oil transportation process.

So that’s why technicians don’t recommend that operators of gas stations refuel their cars when unloading.

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