A "vehicle grounding monitor" helps to avoid dangerous situations through failures or human errors when working with vehicles transporting flammable and combustible products.
Loading or unloading materials into vehicles generate static electricity simply through the movement of the material being processed or handled. As a result, the static electricity accumulated can ignite if the vehicle is not properly grounded.
Create a safer working environment for loading and unloading flammable and combustible products.
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The potential risk of static sparks
Did you know that a relatively insignificant static spark can potentially result in a catastrophic fire or explosion in places with the presence of flammable and combustible materials?
The loading or unloading of flammable and combustible products present a significant danger to:
because of the generation and build-up of electrostatic charges.
The relative motion and interaction of the different materials leads to the instantaneous combination and separation of positive and negative charges.
Consequently, when these charges don't find a way to dissipate from the objects or materials they come in contact with, for instance, if they don't flow to true earth (ground), they become static and increase the electrical potential difference of the object or material on which they are accumulating.
This potential difference is equivalent to a stored source of energy which is instantly seeking to discharge itself in order to return the object to a natural state of electrical equilibrium (Zero Voltage 0V).
Frequently, when this energy is not grounded and allowed to discharge in an uncontrolled manner, it will do so in the form of an electrostatic spark.
If something like this happens in the presence of a vapour or dust produced by flammable and combustible products there is a high risk that ignition of the material will occur.
For instance, tanks, hoses, lances and trucks have a large charge storing capacity, and when this is combined with high potential differences caused by the rapid interaction of liquids and solids it can generate high levels of stored energy ready for uncontrolled discharges.
In order to provide a safe working environment when loading or unloading flammable and combustible products, those responsible in providing a safe working environment must determine all the susceptible areas that have the potential to discharge static sparks, and install the right solution to mitigate these risks.
One of the solutions is to put in place a grounding system (also known as earthing) to connect the vehicle. This operation has one purpose which is to create a good path for electrical current to flow.
Vehicle Grounding: What is it and how does it work?
In terms of electrical engineering, grounding is providing an alternate route for the surplus current or static current to flow into the earth (ground).
In order to ensure that a static charge will not create a spark as result of this difference, a conductive path must be provided to the earth.
Therefore, a proper ground will provide a means for continuously discharging a charged, conductive body to the earth.
Grounding may be achieved by attaching a wire conductor to a javelin embedded in the ground. When using a buried rod, resistance is affected by soil moisture.
This is why it is very important that the grounding system can be checked to ensure that there is continuity and proper resistance.
For instance, when a truck or tanker is loading or unloading and is not adequately grounded, the flow of the product to or from the truck will cause static electricity to build up around the vehicle.
The increase in static electricity will also cause an increase in voltage around the vehicle. Because a certain amount of voltage is needed to create a spark, it is important that the vehicle never reaches a point where any spark can be produced since the surrounding area is considered hazardous.
Unfortunately, there can be failures in the grounding system or human mistakes. Therefore, it's important to incorporate in the grounding system an electrostatic grounding monitor equipment to ensure the correct grounding during the whole process.
Vehicle Grounding Monitor: how to avoid fire and explosions due to failures and human mistakes.
As mentioned before, when a vehicle is not grounded adequately during the process of loading or unloading for instance fuel, the flow of the product to or from the truck will cause static electricity to build-up around the vehicle.
Furthermore, the high build-up of static electricity will increase the voltage around the vehicle that could ignite a spark. Therefore, it's crucial that in an area considered hazardous the vehicle never reaches a point where any spark can be created.
In order to avoid fires and an explosions the driver must connect the truck to the Earth (grounding) before starting any other operations.
But…how does the driver know that the truck is adequately grounded?
The safest way to work is having a device that test the correct grounding. In addition, this device must test the whole process of transferring flammable and combustible material.
This device es called: vehicle grounding monitor. This electronic device ensures that everything is safe and in place before unloading or loading, which means that it is necessary:
- 1To have the grounding system connected to the tank and chassis of the truck
- 2To have the system connected to true earth
- 3That the resistance between the truck and the verified earth ground does not exceed 10 Ohms
How does a vehicle grounding monitor work?
The monitor work with different colour lights that will guide the driver or operator through the process:
Red Light: means that the clamps are disconnected or that the clamps are short circuited, for example, mistakenly connected to the terminal construction.
Yellow Light (in some devices): means that a high impedance discharge is taking place.
Green Light: means that the truck or tanker is grounded correctly but also if the grounding state remains correct.
At the moment that the grounding clamp is attached to the truck (at the designated clamping point) the grounding tester electronics begin to measure the electrical signals to ensure that the clamps are connected to the truck.
This safety feature guarantees that the clamp is not being connected to the other parts of the truck which are isolated from the tank.
In addition, the vehicle grounding monitor or tester electronics ensures that it is connected to a true ground itself through its grounding rod.
The integrity/effectiveness of the grounding rod can be affected somewhat by moisture and temperature so the grounding tester will also ensure that the resistance of the ground rod to the earth is low enough for loading/unloading operations to begin.
Vehicle Grounding Monitor: Not only for trucks or tanks
Likewise you use the vehicle grounding monitors with tank trucks, you can also use it with other vehicles or container for loading/unloading or transferring applications.
These are some examples of the monitors being used in areas with flammable gases and dust, where there is a possibility of ignition due to static electricity:
To sum up, Vehicle Grounding Monitors is a must-have solution to ensure a tanker truck, big bag or railcar is properly grounded before loading or unloading begins. Most importantly, this is a tool that allows you to protect your employees, vehicles and facility from accidents caused by static sparks.