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Grounding of

Tank Trucks

Safe Grounding of Tank Trucks

RELIABLY PREVENTING ELECTROSTATIC CHARGING OF TRUCKS

Due to the high filling speeds, there is always a potential danger of electrostatic charging of the material, the delivery lines or even the tank truck itself when the tank truck is loaded. This is why a means to safely ground the tank truck is necessary to prevent an ignitable spark discharge in potentially explosive atmospheres..

This article provides you with an explanation on what you should keep in mind when grounding the truck, which standards and requirements must be observed and what the best practice entails.

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Yi Chen

Sales Engineer Gas-Ex

Our Whitepaper

All our expert knowledge 

In the whitepaper you will find the following topics:

Grounding of tank trucks
  • Importance of grounding to prevent electrostatic discharge and explosion hazards

  • Overview of different types of tank trucks and their grounding requirements

  • Application examples and success stories
LKW_Test

1

What causes electrostatic charging while loading tank trucks?

During the filling and emptying of trucks, electrostatic contact charging is a frequent occurrence.

 Due to the high delivery speeds of the liquid or solid material, brief contact with the ambient pipelines and tanks does take place. In that moment an exchange of electrons takes place between these components.

However, due to the high delivery speed, the electrons do not have time to return to their starting point. Over time the electrons accumulate on the material with higher electron binding forces, while the number of electrons on the other material declines. This results in different electrical potentials – electrostatic charging takes place.

If the potential difference is too high, the accumulated energy may discharge with a high energetic spark. The energy which is released in this spark is often more than enough to ignite hazardous atmospheres and therefore cause serious damage to the plant and environment.

2

How does grounding the tank truck help combat this danger?

Electrical energy can always accumulate

Electrical energy can always accumulate when the charge ratio exceeds the discharge capability of the material. Specifically, this means:

If conductive material is insulated from the ground potential and contact charging occurs there, a dangerous electrostatic potential difference inevitably builds up, because the energy cannot be discharged fast enough in sufficient quantity. Examples of potentially at-risk areas are the couplings of filling hoses, system pipes, or even the truck’s tank.

This is the point at which the significance of truck grounding becomes so evident. If all conductive areas are equipped with a good grounding connection, the speed of the discharge exceeds the speed of charging. 

This means that energy does not accumulate, thus effectively preventing a hazardous potential difference and possible spark generation.

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3

Requirements need to fulfill

Standards and guidelines 

Having to review all of these variables with respect to the hazard potential takes a lot of time and is very costly. Thankfully, standards and guidelines make things easier for the operators of tank truck filling systems, allowing them to take the correct measures for ensuring safe processes.

They describe workflows, provide guidance on best practice measures, and define maximum leakage resistances. 

 

In particular, what must be observed is:
timm-products-certifications-iecex-international-australia-aurasia

IEC TS 60079-32-1
Explosive Atmospheres – Guidance

4

What does best practice look like for grounding tank trucks?

We differentiate between two types

The type of grounding that meets all requirements and which as such is viewed as best practice depends on the type of tank truck. Here, we differentiate between the following types:


 

Bottom-Loading LKW

With this modern model, filling is performed through hose couplings in the lower, side area of the truck.

The liquids are filled into the tank chambers at a high speed, typically at approx. 2,500L/min.

To prevent overfilling and to ensure grounding at the same time, a combination unit, such as the TIMM EUS-2 should be used. These overfill protection devices are connected to the tank truck using standard plugs in order for grounding to be monitored, while simultaneously reading the fill level sensors of the chambers.

These devices are integrated into the system controller and can thus stop the work process in the event of danger to prevent bursting of the tank chambers and electrostatic charging.


 

Top-Loading LKW

If the tank truck is filled through caps on the top of the tank, ground monitoring is used without additional overfill protection. However, this also requires an interlocking function in the event of an insufficient ground connection to meet best practice requirements.

With a simple ground connection using cable and a clamp, there is always a risk that an undetected cable breakage or other impairment of the discharge capability may have occurred. This potential hazard is effectively ruled out as a result.

In addition to automatic shutdown, best practice grounding devices, such as the Grounding Control Device EKX-4 that uses object detection rule out any capability of manipulating the device or the ground circuit. These devices measure the electrical characteristics of the connected object and verify whether the values are plausible for a truck.

This makes it impossible for the user to inadvertently connect the clamp to a conductive point of the system and in doing so bypass the system or set it to permanent release. A filling release is not issued until the tank truck has been properly grounded.

Do you need to implement electrostatic grounding in your application?

Feel free to reach out to our team of experts.

You are unsure if and how you need to implement electrostatic grounding in your application? 

Or would you like to learn more exact details about the best practice?
Feel free to reach out to our team of experts.

We look forward to helping you.