Physical sealing concerns the prevention of the passage of a solid, fluid or gas. It is measured by the protection class (IP), an international standard.
The IP Code, or Ingress Protection Code, is an international standard of the International Electrotechnical Commission relating to water tightness first published in 1989. It is adopted by the European standard EN 605292.
This index indicates the level of protection offered by a piece of equipment, (a sports watch, a mobile phone, a Bluetooth speaker…), against the intrusion of liquid or solid bodies (dust).
The format of the index is IP XX, where the XX is two digits representing the level of resistance to the intrusion of dust (X on the left) and liquid (X on the right). Each of these Xs can take a value between 0 and 8, depending on its resistance level (the higher the number, the stronger the resistance, see table below).
If there is no corresponding number to define the level of resistance to dust and/or liquid, or if the resistance level has not been tested, either X is not replaced by a number and remains in place. This is the case for IPX7.
Table of Protection Indices
| INDEX | NUMBER 1: PROTECTION AGAINST DUST | NUMBER 2: PROTECTION AGAINST LIQUIDS |
| 0 | No protection | No protection |
| 1 | Protected against solid bodies larger than 50 mm | Protected against vertical drops of water |
| 2 | Protected against solid objects larger than 12 mm | Protected against falling water droplets up to 15° from the vertical |
| 3 | Protected against solid bodies larger than 2.5 mm | Protected against rainwater up to 60° from vertical |
| 4 | Protected against solid bodies larger than 1 mm | Protected against splashing water from all directions |
| 5 | Protected against dust | Protected against water jets from all directions at the lance |
| 6 | Fully protected against dust | Protected against sea spray |
| 7 | – | Protected against the effects of immersion, i.e. a bath of
30 minimum at a maximum depth of one meter |
| 8 | – | Submersible equipment under specified conditions (extended immersion) |
Problems with the IPX7 Rating
The standard is considered incomplete or unclear on some points by industrial designers. For example, the “indefinite” duration of the IPX8 does not guarantee the same protection for all users.
It should also be noted that the protection rating given validates the rating given and not the lower ratings. For example, an IPX7 unit may have been tested to withstand 1m depth for 30 minutes, but tests for protection against strong jets of water may be ignored by some manufacturers.
Tests for IP7X and IP8X are at the discretion of the manufacturer and must be documented, the units must also meet the requirements of the lower protection ratings.
Conclusion on the IPX7 Protection Rating
The IPX7 standard therefore states :
- Protection against dust: Untested
- Protection against the effects of immersion in a maximum depth of 1m and for a maximum of 30 minutes
In other words, we can say that a device certified to the IPX7 standard is truly waterproof. Certification at a lower level, such as IPX4 for example, will just protect the device from splashing water, but you won’t be able to take it into the water for example.
