Capacitors:

As we know that a conductor is surrounded by another conductor, or the electric field lines emitted by one conductor are all terminated in the conductor system of another conductor, which is called a capacitor. Capacitors, as a "container" for storing charges, are one of the most commonly used electronic components. Capacitors play an important role in circuits such as tuning, bypass, coupling, and filtering.

According to the classification outline of the International Maritime Dangerous Goods Code, capacitors are clearly listed in Class 9 dangerous goods and articles, including two classifications:

Capacitor UN3499, double layer (with a storage capacity greater than 0.3Wh);

Capacitor UN3508, asymmetric (with a storage capacity greater than 0.3Wh).

What kind of electronic components are dangerous goods?

According to the International Maritime Dangerous Goods Code, the capacitors with double electric layers (the capacity of storing electric energy is greater than 0.3 wh), articles with non hazardous activated carbon and electrodes used to store electricity, and the double-layer charged capacitors in the loading equipment can be transported under the state of charge, belonging to Class 9 DG, UN3499, and packing guide P003.

According to the requirements of the rules, only double-layer capacitors with a storage capacity greater than 0.3wh are listed as this item. Double layer capacitors with a storage capacity of 0.3wh or less are not included in this list and do not need to follow the requirements of the rules for transportation.

This entry introduces a new concept: energy storage capacity.

Energy storage capacity refers to the electrical energy stored by a capacitor calculated based on its nominal voltage and capacitance, used to measure whether it meets the dividing line of more than 0.3wh.

For all capacitors that meet the classification criteria, including capacitors containing one electrolyte that do not meet any classification criteria for hazardous goods or subcategories, the following standards must be met:

1. Capacitors not installed on equipment must be transported in an uncharged state. Capacitors installed on equipment, or transported without charging, or protective measures taken to prevent short circuits;

2. Each capacitor must take the following protective measures to prevent the risk of short circuits during transportation:

(1) When the storage capacity of a capacitor is less than or equal to 10Wh, or when the storage capacity of each capacitor in a module is less than or equal to 10Wh, the capacitor or module must take protective measures to prevent short circuits, or connect the two poles with metal strips;

(2) When the storage capacity of each capacitor in a separate capacitor or module is greater than 10Wh, the capacitor or module must be connected to the two poles with metal strips;

3. Capacitors containing hazardous materials must be designed to withstand a pressure difference of 95kPa;

4. The design and manufacturing of capacitors must be able to safely release the pressure that may form during use through an exhaust hole or a small gap on the capacitor casing. Any liquid released during exhaust must be collected in containers or equipment installed in capacitors;

Capacitors manufactured after December 31, 2013 must be labeled with Wh for energy storage capacity.

Some additional regulations:

1. Capacitors that contain an electrolyte but do not meet any other hazardous goods classification standards, including capacitors installed in equipment, only need to meet the above requirements.

2. If a capacitor containing an electrolyte that meets any hazardous goods classification standard and has a storage capacity of 10Wh or less, and can withstand a drop test of 1.2 meters on a hard surface without any loss of contents without packaging, it only needs to meet the above requirements and may not follow other rules.

3. Capacitors that contain an electrolyte and meet any hazardous goods classification standards, are not installed in the equipment, and have a storage capacity greater than 10Wh, must not only meet the relevant requirements mentioned above, but also comply with the regulations for the relevant category of hazardous goods.

4. Capacitors installed in the equipment that contain an electrolyte and meet any hazardous goods classification standards are packaged in sturdy outer containers made of appropriate materials. The outer containers designated for such purposes have sufficient strength and appropriate design to prevent accidental operation of the capacitors during transportation, as long as they meet the relevant requirements above and do not need to consider other regulations. Large and sturdy equipment equipped with capacitors that have provided equivalent safety protection can be transported without packaging or on pallets.