What Does the IP Rating of a Load Cell Mean?
The IP (“International Protection” or sometimes “Ingress Protection”) rating of a load cell is an international standard marking on all electrical devices. It specifies how well that electrical device is protected from “ingress” or intrusion of solid objects, liquids, dust or unintentional contact. This marking has a prefix “IP,” followed by two digits (or an “X” in place of a digit) and possibly the letter “K” after the digits. When choosing a load cell for an application, this rating is one of its more critical specs to know. This article further explains this very important load cell specification. (For a real-world example of where this becomes important, see our Knowledge Base article, Giving a crap: How a Simple Toilet and Load Cells are Tackling Global Ills.
IP Rating Format
The two sections below explain the format of the IP rating system of ingress protection. For a quick illustrated summary, see the infographic at the end of this article.
The IP Rating’s Mandatory First Two Digits
According to IEC 60529, the marking’s first two digits after the “IP” are mandatory. IEC 60529 is the standards document that defines the rating system. The first digit gives the device’s protection from intrusion of solid objects, and has a range of 0-6. The second digit ranges from 0-9K and indicates the level of protection from liquids from various angles, pressure and temperature. An “X” appears in place of either digit when there is no known level of protection for that environmental factor.
Note that the IEC specifications have a highest liquid intrusion rating of “8”. The value “9K” comes from the German standard DIN 40050-9, and is widely accepted internationally. This rating implies the device protects against all lower described scenarios of water intrusion.
The tables below define the levels of IP for each mandatory digit.
First Digit: Protection From Intrusion of Solids
| Rating Value | Minimum Object Size of No Ingress |
|---|---|
| 1 | > 50 mm |
| 2 | > 12.5 mm |
| 3 | > 2.5 mm |
| 4 | > 1 mm |
| 5 | Limited dust ingress |
| 6 | Dustproof |
| X | No data available |
Second Digit: Protection From Intrusion of Water
| Rating Value | Scenario of Liquid Exposure Where Protection is Offered |
|---|---|
| 1 | Vertically falling droplets |
| 2 | Droplets falling up to +/- 15 degrees from vertical |
| 3 | Sprayed up to 60 degrees from vertical |
| 4 | Splashed from any direction |
| 5 | Jets of water any direction |
| 6 | Forceful jets of water |
| 7 | Immersion up to 15 meters for 30 minutes or less |
| 8 | Immersion under pressure for any duration |
| 9K (German Standard DIN 40050-9) | High-temperature water jets (for wash-down applications) |
| X | No data available |
The IP Rating’s Optional Alpha Characters
In addition to the mandatory numeric characters, the following alpha characters may optionally appear in an IP rating.
Other Protections
The first optional letter specifies protection from ingress where human interaction is possible, as follows:
| Letter | Avoids Ingress Of |
|---|---|
| A | Back of Hand |
| B | Finger |
| C | Tool |
| D | Wire |
Supplemental Protections
The second optional letter specifies the protection of equipment specific to the following environmental conditions:
| Letter | Meaning |
|---|---|
| H | High voltage apparatus |
| M | Motion during water test |
| S | Stationary during water test |
| W | Weather conditions |
Conclusion
The international standard IP rating appears on all load cells, as you will see if you browse Tacuna Systems’ online load cell catalog. All load cells sold by Tacuna Systems fall into the range of IP65 to IP69K.
The graphic below neatly summarizes the marking’s format.
