Ingress Protection for Industrial Sensors

As has been discussed previously, industrial sensors must be able to withstand some pretty punishing conditions.  Although industrial sensors incorporate some of the same high-end technology found in, say, the blu-ray disc player in your home theater system, it’s not likely that your BD player is going to be subjected to punishing shock, vibration, and general abuse as do the sensors in your industrial machinery.  To be sure, your blu-ray player doesn’t need to be protected against hydraulic fluid or moisture ingress.  Which brings me to the topic of this entry:  Ingress protection for industrial sensors.

In order to be viable in typical industrial environments, industrial sensors must often be able to tolerate getting wet, sometimes really, really wet.  Fortunately, most sensors do indeed incorporate some degree of ingress protection by design.  And it’s pretty easy to choose the proper sensor for a particular set of expected conditions thanks to a method of rating method outlined under international standard IEC 60529.  This standard takes the somewhat vague term “waterproof” and provides specific details as to just how waterproof an electronic device is.

An IP (Ingress Protection) rating for an electronic device typically consists of the letters IP, followed by a two-digit number.  The first digit identifies the protection against intrusion of solid objects (dirt, hand tools, your fingers, etc.):

Level

Object size protected against

Effective against

0

No   protection against contact and ingress of objects

1

>50   mm Any   large surface of the body, such as the back of a hand, but no protection   against deliberate contact with a body part

2

>12.5   mm Fingers   or similar objects

3

>2.5   mm Tools,   thick wires, etc.

4

>1   mm Most   wires, screws, etc.

5

Dust   protected Ingress   of dust is not entirely prevented, but it must not enter in sufficient   quantity to interfere with the satisfactory operation of the equipment;   complete protection against contact

6

Dust   tight No   ingress of dust; complete protection against contact

Most industrial sensors are rated for intrusion protection to IP5_ or IP6_.

The second digit in the IP-rating, which is the one we’re most concerned with, identifies the level of protection again moisture ingress:

Level

Protected against

Testing for

Details

0

Not   protected

1

Dripping   water Dripping   water (vertically falling drops) shall have no harmful effect. Test   duration: 10 minutesWater equivalent to 1mm   rainfall per minute

2

Dripping   water when tilted up to 15° Vertically   dripping water shall have no harmful effect when the enclosure is tilted at   an angle up to 15° from its normal position. Test   duration: 10 minutesWater equivalent to 3mm   rainfall per minute

3

Spraying   water Water   falling as a spray at any angle up to 60° from the vertical shall have no   harmful effect. Test   duration: 5 minutesWater volume: 0.7 litres per   minute
Pressure: 80–100 kN/m²

4

Splashing   water Water   splashing against the enclosure from any direction shall have no harmful   effect. Test   duration: 5 minutesWater volume: 10 litres per   minute
Pressure: 80–100 kN/m²

5

Water   jets Water   projected by a nozzle (6.3mm) against enclosure from any direction shall have   no harmful effects. Test   duration: at least 3 minutesWater volume: 12.5 litres per   minute
Pressure: 30 kN/m² at distance of 3m

6

Powerful   water jets Water   projected in powerful jets (12.5mm nozzle) against the enclosure from any   direction shall have no harmful effects. Test   duration: at least 3 minutesWater volume: 100 litres per   minute
Pressure: 100 kN/m² at distance of 3m

7

Immersion   up to 1 m Ingress   of water in harmful quantity shall not be possible when the enclosure is   immersed in water under defined conditions of pressure and time (up to 1 m of   submersion). Test   duration: 30 minutesImmersion at depth of 1m

8

Immersion   beyond 1 m The   equipment is suitable for continuous immersion in water under conditions   which shall be specified by the manufacturer. Normally, this will mean that   the equipment is hermetically sealed. However, with certain types of   equipment, it can mean that water can enter but only in such a manner that it   produces no harmful effects. Test   duration: continuous immersion in waterDepth specified by manufacturer

While an IP65 rating is fairly common, the trend is towards sensors with a more substantial IP67 or IP68 rating.

While the IP67 rating is fairly straightforward, the IP68 rating seems to cause a lot of confusion.  The reason for this is that the IP68 rating is subject to conditions specified by the manufacturer.  For equipment to be rated to IP68, it must be suitable for continuous immersion underwater at a depth specified by the manufacturer.  Essentially, IP68 can be taken to mean that the equipment is protected at least as well as IP67, but how much better must be specified by the manufacturer of the equipment.

Another IP rating of interest is the IP69K rating.  The IP69K rating, detailed in German DIN standard 40050-9, provides specific requirements (water temperature, pressure, flow rate, etc.) for equipment designed to withstand high-pressure, high-temperature washdown.

Some examples of IP69K-rated sensors include transducers and inductive sensors.

Additional information on Ingress Protection standards can be found here.

This entry was posted in All posts, Inductive Proximity Sensors, Linear Position and Distance Measurement and tagged , , , , , . Bookmark the permalink.

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