AN INTRO TO IP ratings

Susanne Mettberg
Specialist for Industrial Watertight
Products Lumberg Inc. Midlothian, Va.

Will your distribution box continue working if it were to fall into an aquarium? This I/O box from Lumberg Inc. has an IP rating of IP68, so it should.

Will your distribution box continue working if it were to fall into an aquarium? This I/O box from Lumberg Inc. has an IP rating of IP68, so it should.

It's becoming commonplace to read engineering specifications and requirements that talk about “IP20” or “IP68,” but what does it mean?

Simply defined, IP stands for Ingress Protection ratings which are usually assigned to enclosures such as circuit boxes and the lockerlike structures that hold automation controls. Numbers following the letters represent levels of sealing and can range from none at all to “protection against dust and continuous immersion in water.”

The ratings were established by the International Electromechanical Commission and can be found in IEC Publication 529. They were initially developed as a way to classify enclosures, but now provide engineers a convenient, practical way to compare levels of sealing.

Although IP standards were developed for enclosures, they are also applicable to connectors and interconnect products. Although many connectors are protected inside enclosures, many are exposed to the environment and conditions on the factory floor.

IEC usually develops and writes new standards based on field experiences and observations. However, sometimes ideas are generated by users. The IP69K rating, for example, was first proposed by the European food and beverage industry, formalized by the Deutsches Institut fr Normung (DIN, which translates into German Institute for Norms or Standards), and accepted by IEC. The new rating identifies products that can withstand splashdown, i.e., cleaning practices that include temperature extremes, constantly wet environments, and the use of harsh cleaning agents. (In Europe, the standard antimicrobacterial agent used for cleaning is hydrogen peroxide, while in the U.S. the preferred chemicals are alkaline and chlorine bleach.)

Food processors are all preoccupied with sanitation. They have to be because, unlike other factory settings, they must meet uniform cleanliness standards set by local health departments. And you cannot put just any equipment into those types of environments and expect it to survive. Food-processing plants can be filled with butchered animals, bacteria, waste products, and are cleaned often with harsh chemicals and water washdowns.

That's why our company is making enclosures and connectors out of stainless steel. It can endure constant exposure to harsh cleaning agents and water. The first product, an M-12 actuator/ sensor box, has no sharp creases or crevices, just smooth rounded edges that give bacteria no place to settle. It was one of the first products to earn an IP69K rating. But what kind of rigors does a product have to endure to achieve an IP69K rating?

The product must operate while fixed on the center of a rotary table turning at 5 rpm while being sprayed with water from a flat-stream nozzle. Spraying is done for 30 sec from 0, 30, 60, and 90°. The nozzle must be 3.9 to 5.9 in. away from the product. The flow rate must be between 3.6 and 4.2 gpm, with water pressure between 1,160 and 1,450 psi at a temperature of 176°F to ±9°F. While this testing might seem extreme to some, these are typical of the conditions produced by food processors, especially seafood processors.

The bottom line for all food processors is the same. If equipment fails due to splashdown, it equates to downtime. Downtime is unacceptable because it is synonymous with financial loss. With refrigeration equipment, it can mean lost inventory. In packaging and processing, it can mean lower productivity and wasted labor. Equipment failure is not an option.

IP RATINGS

First
Number

Protection against
(dust, foreign object)

Second
number
Protection
against (water)
0
None
0
None
1
Solid objects larger than 50 mm
1
Vertically falling water drops
2
Solid objects larger than 12.5 mm
2
Vertically falling water drops even when enclosure is tilted up to 15 degrees
3
Solid objects larger than 2.5 mm
3
Spraying water
4
Solid objects larger than 1.0 mm
4
Splashing water
5
Dust
5
Water jets
6
Dustlight
6
Powerful water jets
   
7
Temporary immersion in water
   
8
Continuous immersion in water
The chart breaks down Ingress Protection as it relates to sealing against the entry of solid or liquid objects. This system is the most uniform and widely used of its kind in industry. In its simplest form, the classification system consists of the letters "IP" followed by two numbers, which represent increasingly greater sealing against solid objects and liquids. For example, a product with an IP55 rating provides some protection from penetration by dust and a jet spray of water, but it would not be expected to seal out all water if it were completely immersed. A product rated IP67, on the other hand, would also be "dusttight" but would remain completely sealed despite being immersed in water for 30 min to a depth of 1 meter.

 

IEC
Back in 1904, the foresighted International Electrical Congress was hosting a number of delegates in St. Louis in 1904 when they drafted a report saying, “...steps should be taken to secure the cooperation of the technical societies of the world, by the appointment of a representative Commission to consider the question of the standardization of the nomenclature and ratings of electrical apparatus and machinery.” Within two years, the International Electromechanical Commission (IEC) was officially founded in June 1906, with headquarters set in London. In 1948, the IEC moved its permanent headquarters from England to Switzerland where it still resides.

By 1914, the IEC boasted four technical committees that developed standards, nomenclature, definitions and ratings. By 1980, that number had grown to 80. In 2001, the IEC published its most recent edition of the IEC Multilingual Dictionary, containing 18,500 electrotechnical concepts divided into 73 subject areas, with full definitions in French and English and equivalent terms in 12 languages, including an index in German. Today, the IEC views itself as the “leading global organization that prepares and publishes international standards for all electrical, electronic, and related technologies.”