Technical information

Notes on equipment protection per IEC/EN 60529 and NEMA
For Bourdon tube or diaphragm pressure gauges
WIKA data sheet IN 00.18

General information
This technical information describes the measures to prevent
both the formation of condensation within a hermeticallysealed case, and also the intrusion of water into cases
vented to the atmosphere. These measures apply both toBourdon tube pressure gauges and to diaphragm pressuregauges.

1. Introduction and explanation of physical conditions
The formation of condensation in the cases of hermeticallysealed, unfilled instruments cannot generally be avoided.
This is based on the physical fact that the humidity found inair, under particular conditions, settles on cold surfaces ascondensation. The warmer the air, the more humidity it canhold. If the air cools (e.g. at the window of a measuring instru-ment), then the air can only hold a small amount of humidity.
The excess humidity settles as condensation on the window.
In addition, water in the form of splash, jet and rain waterfrom outside can intrude into the case, so long as the instrument is vented to atmosphere.

2. Explanation of the degrees of protection per IEC/EN 60529
Degrees of protection against solid foreign bodies, defined by the first index numberFirst index
numberDegree of protection

0Not protected

123456

Code designation

Definition

Protected against solid foreign bodies of 50 mm
diameter and larger

The object probe, a round body of 50 mm diameter, must not fully
intrude 1)

Protected against solid foreign bodies of 12.5 mm
diameter and larger
Protected against solid foreign bodies of 2.5 mm
diameter and larger–The object probe, a round body of 12.5 mm diameter, must not fully
intrude 1)
The object probe, 2.5 mm in diameter, must not intrude at all 1)

Protected against solid foreign bodies of 1.0 mm
diameter and larger

The object probe, 1.0 mm in diameter, must not intrude at all 1)

Dust-proof

No ingress of dust

Dust protected

Ingress of dust is not completely prevented, but dust may not intrude
in a such a quantity that the satisfactory operation of the instrument orsafety is impaired

1) The full diameter of the object probe must not pass through any opening in the case.

Illustration 1
Source: IEC/EN 60529
WIKA data sheet IN 00.18 ∙ 0x/2019

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Degrees of protection against water, defined by the second index number
Secondindex
number01

Degree of protection
Code designation
Not protected

Protected against dripping water2

Protected against dripping water when the case isinclined to 15°.

3

Protected against sprayed water

4

Protected against splash water

5

Protected against water jets

6

Protected against strong water jets

7

Protected against the effects of temporary immersion
in water8

Protected against the effects of permanent immersion
in waterDefinition–

Perpendicularly falling drops must have no damaging effects.

Perpendicularly falling drops must have no damaging effects, when
the case is inclined to an angle of up to 15°, either side of perpendicular.

Water that is sprayed at an angle of up to 60°, either side of perpendicular, must have no damaging effects.

Water that splashes against the case from any direction must haveno damaging effects.

Water that splashes against the case, as a jet, from any direction,must have no damaging effects.

Water that splashes against the case, as a strong jet, from any
direction, must have no damaging effects.

Water must not enter in any quantity which could cause damage,when the case, under standardised pressure and temperature
conditions, is temporarily immersed in water.

Water must not enter in any quantity which could cause damage,when the case is permanently immersed in water, under conditions
which must be agreed between the manufacturer and user. The
conditions must, however, be more demanding than those for theindex number 7.

Illustration 2

Source: IEC/EN 60529

Example: Ingress protection IP65
■ First index number 6:Dust-proof, no ingress of dust

■ Second index number 5: Protected against water jets: Water that splashes against the case as a jet from any direction

must have no damaging effects.

3. Comparison of NEMA (National Electrical Manufacturers Association) and
IEC/EN 60529
NEMA ingress protection
Model number

IEC/EN 60529 ingressprotection
Classification

1IP10

3IP54

3SIP54

5IP52

12 and 12 K

IP52

2IP113RIP144 and 4 X

IP66

6 and 6 PIP67

13IP54Illustration 3WIKA data sheet IN 00.18 ∙ 0x/2019

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4. Measures against the formation of condensation
Different fill fluids depending on the ambient temperature and the electrical conductivity
In order to avoid the formation of condensation in the case,
WIKA recommends filling the instruments with glycerine.
For contact gauges, the filling can be made with silicone oil,since silicone oil, unlike glycerine, is not hygroscopic andtherefore prevents a short-circuit within the instrument.

If the ambient temperature drops below -20 °C, then werecommend that the instrument absolutely must be filled withsilicone oil. Even at temperatures down to -50 °C, silicone oil
can still be used due to its low viscosity.
For flammable and/or explosive media, e.g. oxygen, inert fillfluids must be used.

5. Hermetically sealed instruments and effects associated with them
In order to prevent the intrusion of water into the case, it isrecommended that an ingress protection method is chosenthat reliably inhibits this (see illustrations 1 and 2). The
ingress protection demands that the instrument is hermetically sealed.

With vented instruments, the vent valve has to be closed
in order to achieve the specified ingress protection. This,
however, produces a temperature error, which can affect themeasuring result (see illustrations 4, 5 and 6). Therefore thevent valve has to be opened for a short time before reading
the measured value.

5.1 Temperature errors in unfilled and filled Bourdon tube pressure gauges
A standard 232.50/30 instrument with a pressure range
greater than 25 bar can be made hermetically sealed without
any problems, and manufactured with an ingress protection of IP66. The temperature error that occurs with these
instruments is negligible, since it is so small in relation to thepressure range, that the instrument still will operate within its
specified class accuracy.

Instruments with a scale range of less than 25 bar can
likewise be made hermetically sealed, though a temperatureerror will then be present (see illustration 4). The temperatureerrors present are shown in the following graphs.

Influence in %Temperature errors in hermetically sealed, unfilled Bourdon tube pressure gauges

Illustration 4WIKA data sheet IN 00.18 ∙ 0x/2019

Adjusted at 20 °C

Temperature in °C

Page 3 of 6

Temperature errors in hermetically sealed, filled Bourdon tube pressure gauges

Influence in %Filled to 90 % with glycerine

Illustration 5Temperature in °C

Influence in %Filled to 90 % with silicone oil

Illustration 6
WIKA data sheet IN 00.18 ∙ 0x/2019

Temperature in °C
Page 4 of 6

5.1 Temperature errors in unfilled and filled diaphragm pressure gauges
With model 4, 5 and 7 hermetically sealed diaphragmpressure gauges, the temperature error for scale ranges≥ 100 mbar is negligible. For scale ranges < 100 mbar werecommend only using instruments with a pressure compensating diaphragm.

For instrument models 7xx.14, DPG40, DPGS40,DPGS40TA, DPGT40, DPS40, 700.01/02 and 7x2.15, due totheir mechanical design, there are no additional temperatureerrors.

5.3 Model overview
Pressure gauges for which the formation of condensation and the ingress of water from the outside can beprevented:
Influence

Bourdon tube pressure gauges
Model 2unfilled≥ 25bar< 25barFormation ofcondensation

unavoidable

Hermeticallysealed 1)

Influencenegligible

For influence
seeillustration 4

Diaphragm pressure gauges

Model 4 and 7
Model 2 filled Model
unfilled
233.30filled, withpressurecompensating
diaphragm≥ 25 < 25
all pres> 100 < 100bar bar
surembar mbar
rangesModel 4 andModel 4 and 7 Model 4
7 filled, withfilled
and 7 unfilled, with pressurecompensatpressurecompensat- ing diaphragming diaphragm> 100 < 100 all pressure all pressure
mbar mbar ranges
ranges

unavoidableunavoidable

InfluencenegligibleFor
influencesee illustration 5or 6

Influencenegligible

Influencenegligible

TechnicallynotsolvableTechnicallynotsolvable

1) Hermetically sealed = air-tight case

Illustration 7

6. Pressure compensating diaphragmAs can be seen in illustration 7, formation of condensationin filled pressure gauges can be prevented by the use ofpressure compensation diaphragms, without any temperature error. Pressure compensation diaphragms can be used
for all safety pressure gauges per EN 837-1 S3.

Plastic diaphragm

Illustration 8: Rear wall of case with pressure compensating diaphragm, nominal size 63

WIKA data sheet IN 00.18 ∙ 0x/2019

Illustration 9: Rear wall of case with pressure compensating diaphragm, nominal size 100

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Plastic diaphragm

Illustration 10: Rear wall of case with pressure compensating diaphragm for contact gauges,
nominal size 160

Blow-out rear wall withpressure compensatingdiaphragm

SocketPressure element

Case with solid
baffle wall

Process connection Movement withinterchangeable
movement retainer

WindowLaminated safety glass

Dial

Pointer

Sealing

Bayonet ring

Illustration 11: Exploded view drawing

0x/2019 EN© 09/2010 WIKA Alexander Wiegand SE & Co. KG, all rights reserved.
The specifications given in this document represent the state of engineering at the time of publishing.
We reserve the right to make modifications to the specifications and materials.

WIKA data sheet IN 00.18 ∙ 0x/2019

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