IP 69K, IP 67 etc. - an introduction
Product specifications with details such
as IP 54, IP 67, etc. have become widely
established. For the most part, there is
a mention that the latter is a degree of
protection. Even amongst specialists,
however, many are unable to interpret the
abbreviation correctly.
Whilst the letter pair “IP” stands for
“ingress protection”, the meaning of the
numbers is considerably more complicated.
Most users do not even know where the
definitions of these specifications could
be looked up - a problem that frequently
causes application failures. The following
explanations should contribute to a better
understanding of this important specification.
IEC 60529
The relevant standard is IEC publication
IEC 60529, formerly IEC 529 (IEC stands
for International Electrotechnical Commission), first published in 1989. It can be obtained directly from the IEC (address at the
end of this article). Originally intended for
housings, its scope has been extended during the course of time, and today includes a
multitude of devices, including sensors and
connecting cables. The standard has been
extended, translated and modified several
times. Of particular interest is the European,
i.e. German equivalent DIN 40050.
As a general rule, IEC standards are
created by teams of IEC specialists (technical committees), consisting of representatives of manufacturers and end-users from
member states. IEC 60529 is the work of
Technical Committee 70. However, national
standards are not infrequently used as the
basis for international standards and their
further evolution.
direction. This degree
Picture 1
of protection primarily
concerns the resistance
of electrical production
equipment to cleaning using high-pressure jets, where there
are requirements with
respect to pressure,
increased temperature
(hot water) and highly
active chemical cleaning and disinfecting
agents (in particular,
hydrogen peroxide,
but also other alkali
IP 68 & IP 69K
and chlorine-containing
products). Cleaning in
the food sector is, as a
rule, coupled with disinfection, which requires the use of further, generally aggressive
additives. Although cleaning with high-pressure jets is highly effective, this method
First digit: Meaning with regard to
the protection of electrical equipment
against the penetration of solid foreign
objects (including dust)
0 not protected
1 with diameter ≥ 50 mm
2 with diameter ≥ 12.5 mm
3 with diameter ≥ 2.5 mm
4 with diameter ≥ 1 mm
5 dust protected
6 dust-tight
IP 69K
Here, DIN (Deutsches Institut für
Normung / German Institute for Standardization), whose standards frequently first
become EN standards (with validity in the
EU) before then becoming IEC standards,
is particularly active. Standardization of the
IP degrees of protection followed exactly
this path. Encountering great interest, the
relatively new degree of protection IP 69K
resulted from the demands of the European food industry. Requests from utility
vehicle manufacturers tended in the same
Second digit: Meaning with regard to
the protection of electrical equipment
against ingress of water
0 not protected
1 vertically falling drops
2 vertically falling drops (15o inclination of the test piece)
3 spraying water
4 splashing water
4K splashing water with increased
pressure
5 water jets
6 powerful water jets
6K powerful water jets with increased
pressure
7 temporary immersion
8 continuous immersion
9 not defined
9K high-pressure / steam-jet cleaning
An overview of IP degrees of protection according to IEC 60529 / DIN 40050. The
table is divided into a number of criteria for the penetration of solid and liquid objects, as well as dust. The abbreviation of an IP degree of protection consists of
the recurrent letters “IP”, followed by the first and second digits according to the
above table. As a general rule, the higher the digit, the better the protection. The
commonly used degree of protection IP 54, for instance, stands for dust protection,
which includes protection against the penetration of large and small solid foreign
objects, as well as protection against splashing water, but not immersion in water.
Inset 1
also aggressively attacks metals and plastics of all kinds. Particularly concerned is the
electrical equipment of food-processing installations, worst of all the sensors, which
are already particularly exposed. As a result of this situation an appendix (DIN 40050
part 9) was added to DIN 40050, which includes a definition of IP 69K (amongst others),
describing an elaborate, standardized test procedure for production equipment.
Testing
In the IP 69K test, the device to be tested is mounted on a rotating table turning at
5 revolutions per minute. During the course of the test, the test piece is splashed for
30 seconds from each of the angles of 0, 30, 60 and 90o. The jet comes from a flat
nozzle at a distance of 100 to 150 mm and has a temperature of 80 ± 5 oC, a delivery
rate of 14 to 16 l/min and a pressure of 8,000 to 10,000 kPa (80 - 100 bar) (fig. 1).
These conditions may seem extreme, but are, however, typical for applications in the
food-processing industry.
It only remains to be said that the really
tricky part is actually satisfying all three
requirements simultaneously.
Seals
Elastic materials are generally chosen
for the sealing, as well as for eventual connecting cables. However, elastic materials
are rather unsatisfactory when exposed
to mechanical forces, which is precisely
the case with high-pressure jets. The
standard solution consists of mechanically
pretensioning the sealing materials to such
an extent that the forces created by the
jet are guaranteed to be inferior, even at
increased temperatures and over a long
period of time.
Choice of material
Water jet from a distance
of 100 to 150 mm
Jet for 30 seconds from
every angle
Delivery rate: 14 – 16 l/min
Water pressure: 80 - 100
bar (8,000 – 10,000 kPa)
Rotation at 5 rpm
The ultimate material for metal parts
is stainless steel. From the wide range of
available types on the market, there are
some that have the necessary chemical
resistance (V4A, i.e. AISI 316L). With regard
to plastics, although Teflon could fulfil all the
requirements without problem, its price and
complicated processing requirements are
an obstacle. As an alternative, the ubiquitous PVC can do the job, since its chemical
resistance is perfectly sufficient. However,
not all countries permit the use of PVC in
the food industry, since its raw materials
are strongly carcinogenic. However, in the
wide range of plastics available, there are
sufficient alternatives.
Resistance to temperature change
Temperature-change resistance is a
complex matter. Since it is not specified
in IP 69K, its great importance for the
long-term reliability of sensors is merely
pointed out here.
Fig. 1
Product development for IP 69K applications
To pass this test, what do products have to be like? First and foremost, the following
3 problem areas must be tackled:
- The seals must prevent the damaging penetration of liquids, even under pressure
- The materials must be able to resist the chemicals and the temperature.
- The electronics must be able to withstand the temperature changes.
The real objective of IP standardization
should not be lost from sight. Operators of
manufacturing facilities want their installations to be in use as much as possible,
which requires as low a rate of component
failures as possible. Failures during operation, with the corresponding downtimes,
are extremely costly, and thus totally unacceptable. But even “plannable” failures,
such as the preventive replacement of
components, are problematic. The costs
of such preventive maintenance, after a
few cycles already, nearly always bear no
relation to the actual component prices.
The only valid alternative is obvious: The
components of an installation must outlive
the latter’s planned operating life, with no
ifs or buts.
Other IP degrees of protection
Although other more commonly encountered degrees of protection, such
as IP 67 and IP 68 are, at first sight, less
problematic, quite the opposite is, in
fact, found in practice. With IP 67, users
often mistakenly assume that devices so
specified can be operated in any liquid for
any length of time. Both assumptions are
false, since the standard is unambiguous
in this respect. The liquid must be water,
and the test piece immersed to a depth of
1 meter for 30 minutes. In the case of IP
68, on the other hand, the standard itself
is ambiguous. Although operation under
water for an unlimited time is required (or
rather suggested), the small print is, however, exceedingly non-committal. As for IP
67, the liquid is water, but the immersion
depth and the guaranteed immersion duration, however, have to be negotiated on
a case-by-case basis by the “users of the
standard”, i.e. in practice the manufacturers
and end-users.
In addition, it has to be pointed out that
the higher degree of protection IP 69K in
no way also implies IP 67 or IP 68. Quite
the opposite is true, so that these must be
stated additionally and independently, i.e.
“IP 68 & IP 69K”, for instance.
Products
There is a huge demand for products,
particularly sensors, that conform to IP
69K. The corresponding offer is, at present
however, still limited. The new Contrinex
series 700L inductive proximity switches
can be regarded as a particularly successful realization of the requirement profile. Of
particular interest is that, at the all-important
place, i.e. the sensing face, a radical solution has been implemented. The device
housings are turned from solid metal, with
no plastic joints, which means that the
most important weak point of conventional
devices is eliminated (picture 2).
In all other aspects too, this product range is
completely optimized for the intended application
location. With special stainless steel (V4A / AISI 316L),
special cable (TPE-S), special plastics, a particularly
resistant cable entrance
point, increased operating temperature range
and, last but not least,
laser engraving instead
of labels or printing, the
product leaves virtually
nothing to be desired (picture 3). The well-known
advantages of the standard series 700 range are
retained, in particular
the long operating disPicture 2
tance, achieved also on
non-ferrous metals. The
switches are thus ideal for use in the food and pharmaceutical
industries, where IP 69K is frequently a prerequisite.
Picture 3
Historical facts
DIN - Deutsches Institut für Normung e.V. (German Institute for
Standardization)
No industrial society without standards. Alongside patents and licenses, they
provide a reliable system for the organization of innovations, new products and even
services. The main activity of DIN is the writing of technical rules. The objective
of DIN is to create standards for the benefit of the economy and of society as a
whole. DIN offers a forum where representatives of the manufacturing industries,
commerce, trade and science, service industries and end-users meet, where anyone
with an interest in standardization may discuss the latest state-of-the art technology
and record the results in German Standards.
DIN was established on 22 December 1917 as the “Normenausschuss der
deutschen Industrie (NADI)”, the Standards Association of German Industry. In
March 1918, the first German Standard was published (DIN 1 Surfacing pins). In
1920, the DIN mark was registered as a trademark with the patent office. In 1922,
DIN 476 Paper sizes (DIN A 4 etc.) was published.
Today, DIN, Deutsches Institut für Normung e.V. (company trademark DIN), with
its headquarters in Berlin, is Germany’s national standardization organization. In
collaboration with commerce, industry, science, end-users and government offices,
the association promotes technical standards for rationalization and quality assurance. DIN also represents German interests in international standard committees,
such as, for instance, ISO, IEC and CEN.
Already in 1904, the farsighted International Electrical Congress, which at the
time hosted a large number of delegates in St. Louis, drafted a report that said “…
steps should be taken to secure the co-operation 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”. In less than two years, in June 1906, the International Electrotechnical
Commission (IEC), with headquarters in London, was officially founded. In 1948,
the IEC moved its permanent headquarters from England to Switzerland, where it
remains to this day.
In 1914, the IEC could already boast the foundation of four technical committees that developed standards, nomenclatures, definitions and ratings. By 1980,
this number had climbed to 80. In 2005, the Commission published the most recent
edition of its IEC Multilingual Dictionary, which contains 19,400 electrotechnical definitions in French and English and equivalent terms in 13 languages. Consolidated
indexes are available in English and French, as well as in German and Spanish.
Today, the IEC considers itself the leading global organization for the preparation
and publication of international standards for all electrical, electronic and related
technologies.
Contact for IEC standards:
Contact for DIN standards:
International Electrotechnical Commission
3, rue de Varembé
CH-1211 Geneva 20
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
E-mail: info@iec.ch
Internet: www.iec.ch
Beuth Verlag GmbH
D-10772 Berlin
Tel.: +49 30 2601-0
Fax: +49 30 2601-1260
E-mail: postmaster@beuth.de
Internet: www.beuth.de
Contrinex AG Industrial Electronics
route André Piller 50 - CH-1762 Givisiez - Switzerland
Tel: +41 26 460 46 46 - Fax: +41 26 460 46 40
Internet: www.contrinex.com - E-mail: info@contrinex.com
 Contrinex AG 2009
Dipl.-Ing. Peter Heimlicher studied electronics at the ETH in Zurich. In 1972, immediately after his studies, he founded Contrinex AG, of which he has been CEO
ever since. His company has specialized in the manufacture of high-performance
sensing devices for industrial applications.