Process Environment
Enclosure Standards and Protection Concepts
NEMA Enclosure Standards
/&."/BUJPOBM&MFDUSJDBM.BOVGBDUVSFST"TTPDJBUJPO
has established standards for enclosures to provide
protection from environmental contamination. A description
of the more common standards is listed below. Type
EFGJOJUJPOTBSFGSPN/&."'PSNPSFEFUBJMFE
BOEDPNQMFUFJOGPSNBUJPO/&."4UBOEBSET1VCMJDBUJPO
“Enclosures for Electrical Equipment (1000 Volts
Maximum)” should be consulted. This Standards Publication,
BTXFMMBTBMMPUIFS/&."QVCMJDBUJPOTJTBWBJMBCMFGSPN
*)4BU
Standards for Non-Hazardous Locations
Type 1: Enclosures constructed for indoor use to provide
Type 5: Enclosures constructed for indoor use to provide
a degree of protection to personnel against incidental
DPOUBDUXJUIUIFFODMPTFEFRVJQNFOUBOEUPQSPWJEFBEFHSFFPG
protection against falling dirt.
Type 2: Enclosures constructed for indoor use to
provide a degree of protection to personnel against
JODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUP
provide a degree of protection against falling dirt, and
to provide a degree of protection against dripping and light
TQMBTIJOHPGMJRVJET
Type 3: Enclosures constructed for either indoor or
outdoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSUSBJO
TMFFUTOPXBOEXJOECMPXOEVTUBOEUIBUXJMMCFVOEBNBHFECZ
the external formation of
ice on the enclosure.
Type 3R: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
personnel against incidental contact with the enclosed
FRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
SBJOTMFFUBOETOPXBOEUIBUXJMMCFVOEBNBHFECZUIF
external formation of ice on the enclosure.
Type 3S: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
personnel against incidental contact with the enclosed
FRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
SBJOTMFFUTOPXBOEXJOECMPXOEVTUBOEJOXIJDIUIFFYUFSOBM
NFDIBOJTNT
SFNBJOPQFSBCMFXIFOJDFMBEFO
Type 4: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSUSBJO
sleet, snow, windblown dust, splashing water, and hose-directed
XBUFSBOEUIBUXJMMCFVOEBNBHFECZUIFFYUFSOBMGPSNBUJPOPG
ice on the enclosure.
Type 4X: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSUSBJO
sleet, snow, windblown dust, splashing water, hose-directed
XBUFSBOEDPSSPTJPOBOEUIBUXJMMCFVOEBNBHFECZUIFFYUFSnal formation of ice on the enclosure
a degree of protection to personnel against incidental
DPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPG
QSPUFDUJPOBHBJOTUGBMMJOHEJSUBHBJOTUTFUUMJOHBJSCPSOFEVTUMJOU
GJCFSTBOEGMZJOHTBOEUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTU
ESJQQJOHBOEMJHIUTQMBTIJOHPGMJRVJET
Type 6: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
against hose-directed water and the entry
of water during occasional temporary submersion at
BMJNJUFEEFQUIBOEUIBUXJMMCFVOEBNBHFECZUIF
external formation of ice on the enclosure.
Type 6P: Enclosures constructed for either indoor
or outdoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
against hose-directed water and the entry
PGXBUFSEVSJOHQSPMPOHFETVCNFSTJPOBUBMJNJUFEEFQUIBOE
that will be undamaged by the external formation
of ice on the enclosure.
Type 12: &ODMPTVSFTDPOTUSVDUFEXJUIPVULOPDLPVUT
for indoor use to provide a degree of protection to
QFSTPOOFMBHBJOTUJODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
against circulating dust, lint, fibers, and
GMZJOHTBOEBHBJOTUESJQQJOHBOEMJHIUTQMBTIJOHPGMJRVJET
Type 12K: &ODMPTVSFTDPOTUSVDUFEXJUILOPDLPVUT
GPSJOEPPS
use to provide a degree of protection to personnel against
JODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOU
UPQSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSUBHBJOTU
DJSDVMBUJOHEVTUMJOUGJCFSTBOEGMZJOHTBOEBHBJOTUESJQQJOH
BOEMJHIUTQMBTIJOHPGMJRVJET
Type 13: Enclosures constructed for indoor use to
provide a degree of protection to personnel against
JODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOUUP
QSPWJEFBEFHSFFPGQSPUFDUJPOBHBJOTUGBMMJOHEJSU
BHBJOTUDJSDVMBUJOHEVTUMJOUGJCFSTBOEGMZJOHTBOE
against the spraying, splashing, and seepage of water,
oil, and non-corrosive coolants.
Standards for Hazardous Locations SFQMBDFECZ/&$$&$)B[BSEPVT"SFB$PEFT
Type 7: Enclosures constructed for indoor use in hazardous
Type 9: Enclosures constructed for indoor use in
Type 8: Enclosures constructed for either indoor or
Type 10: &ODMPTVSFTDPOTUSVDUFEUPNFFUUIFSFRVJSFNFOUTof
UIF.JOF4BGFUZBOE)FBMUI"ENJOJTUSBUJPO$'31BSU
MPDBUJPOTDMBTTJGJFEBT$MBTT*%JWJTJPO(SPVQT"#$PS%
BTEFGJOFEJO/'1"
outdoor use in hazardous locations classified as Class I, Division
(SPVQT"#$BOE%BTEFGJOFEJO/'1"
IB[BSEPVTMPDBUJPOTDMBTTJGJFEBT$MBTT**%JWJTJPO
(SPVQT&'PS(BTEFGJOFEJO/'1"
valve communication and control
Comparison of Specific Applications of Enclosures for Outdoor Nonhazardous Locations
Type of Enclosure
Provides a degree of protection against the
following environmental conditions
3
*ODJEFOUBMDPOUBDUXJUIUIFFODMPTFEFRVJQNFOU
9
3R*
3S
9
9
4
4X
9
9
6
9
6P
9
3BJOTOPXBOETMFFU
9
9
9
9
9
9
9
4MFFU
y
y
9
y
y
y
y
8JOECMPXOEVTUMJOUGJCFSTBOEGMZJOHT
9
y
9
9
9
9
9
)PTFEPXO
y
y
y
9
9
9
9
$PSSPTJWFBHFOUT
y
y
y
y
9
y
9
0DDBTJPOBMUFNQPSBSZTVCNFSTJPO
y
y
y
y
y
9
9
0DDBTJPOBMQSPMPOHFETVCNFSTJPO
y
y
y
y
y
y
9
* These enclosures may be ventilated.
** External operating mechanisms are not required to be operable when the enclosure is ice covered.
*** External operating mechanisms are operable when the enclosure is ice covered.
IEC Enclosure Standards
The International Electrotechnical Commission has
established enclosure standards for protection from
environmental contamination as shown below. These
standards are used widely in Europe, the Middle East,
Africa and parts of Asia.
Example:
IP
6
7
Ingress Protection
Protection Against Solid Bodies
Protection Against Liquids
Protection Against Liquids
0: no special protection
1: protected against vertical falling water drops
2: protected against vertical falling water drops when
3:
4:
5:
6:
7:
8:
FODMPTVSFJTUJMUFEBU×
protected against sprayed water
protected against splashing water
protected against water jets
protected against heavy seas
protected from the effects of temporary immersion
protected from the effects of continuous immersion
Process Environment
Protection Against Solid Bodies
0: no special protection
1: QSPUFDUFEBHBJOTUTPMJEPCKFDUTHSFBUFSUIBOPGNN“
2: QSPUFDUFEBHBJOTUTPMJEPCKFDUTHSFBUFSUIBONN“
3: QSPUFDUFEBHBJOTUTPMJEPCKFDUTHSFBUFSUIBONN“
4: QSPUFDUFEBHBJOTUTPMJEPCKFDUTHSFBUFSUIBONN“
5: dust protected
6: dust-tight
Process Environment
Hazardous Area Descriptions
National Electrical Code (NEC) 500
5SBEJUJPOBMTUBOEBSETVTFEJO/PSUI"NFSJDB
Example:
Class I, Div 1, Group B, C, D, T4
Permitted Class
Permitted Division
Permitted Group
Temperature Class
Permitted Class
Class I: Gas Vapors
Class II: Dusts
Class III: Fibers
Permitted Division
Division 1: Gasses or
vapors exist under normal
conditions
Division 2: Gasses or
vapors are present but
are normally contained
and can escape only
through accident or
abnormal operation
Permitted Group
Group A: Acetylene
Group B: Hydrogen or
&RVJWBMFOUT
Group C: Ethyl Ether,
Ethylene or Cylclopropane
Temperature Class*
T1: ×$×'
T2: ×$×'
T3: ×$×'
T4: ×$×'
T5: ×$×'
T6: ×$×'
Group D: Gasoline, hexane,
naphtha, benzene, butane,
propane, alcohol, acetone,
CFO[PMMBDRVFSBOE
natural gas
Group E: Metal Dust
Group F: $BSCPO#MBDL
Group G: Flour, starch,
* Device may be exposed
to gases whose ignition
temperature is higher than
this value.
grain dusts
National Electrical Code (NEC) 505
/PSUI"NFSJDBO4UBOEBSETEFWFMPQFEUPIBSNPOJ[FXJUI
IEC standards.
Permitted Class
Permitted Zone
Class I: Gas Vapors Zone 0:
Gas present
Class II: Dusts
continuously
Class III: Fibers
Zone 1:
Gas present
intermittently
Zone 2:
Gas present
under abnormal
operation
Example:
Permitted Class
Permitted Zone
Method of Protection
Intrinsically Safe Output
Gas Group
Temperature Class
Protection Method
e: *ODSFBTFE4BGFUZ
OPBSDTTQBSLTPS
hot surfaces
d*: 'MBNFQSPPG
contain explosion
BOERVFODIGMBNF
m: &ODBQTVMBUJPO;POF
LFFQGMBNNBCMFHBTPVU
nA:/POTQBSLJOHFRVJQNFOU
nC:4QBSLJOHFRVJQNFOU
in which the contacts
are suitably protected
other than by restricted
breathing enclosure
nR:Restricted breathing
*[ia]: Intrinsically safe,
;POFBOE
*[ib]: Intrinsically safe,
;POFBOE
Class I, Zone 1, AEx d [ia] IIC T4
Gas Group
IIC: Acetylene
IIB + H2: Hydrogen or
FRVJWBMFOUT
IIB: Ethyl Ether, Ethylene
or Cylclopropane
IIA: Gasoline,
hexane, naphtha,
benzine, butane,
propane, alcohol,
acetone, benzol,
MBDRVFSBOE
natural gas
Temperature Class*
T1:
T2:
T3:
T4:
T5:
T6:
×$×'
×$×'
×$×'
×$×'
×$×'
×$×'
* Device may be exposed
to gases whose ignition
temperature is higher
than this value.
valve communication and control
IEC & EU (European) Standards
5IF*&$*OUFSOBUJPOBM&MFDUSPUFDIOJDBM$PNNJTTJPO
NBSLJOHTBSFBTGPMMPXT
Example:
Ex
d
IIB
T3
Explosion Protection
Type of Protection
Gas Group Classification
Temperature Classification
Type of Protection
d: flameproof enclosure - contain explosion
BOERVFODIGMBNF
p:
ia:
ib:
o:
s:
e:
pressurized enclosure - fill with inert gas
JOUSJOTJDBMMZTBGFGPS;POFMJNJUFOFSHZ
*OUSJOTJDBMMZTBGFGPS;POFMJNJUFOFSHZ
oil immersion
Gas Group Classification
IIC: Acetylene and hydrogen
IIB: Diethel ether, ethylene,
cyclopropane and others
IIA: Gasoline, hexane, butane,
naphtha propane, isoprene
and many others
Temperature Classification*
T1: ×$×'
T2: ×$×'
T3: ×$×'
T4: ×$×'
T5: ×$×'
T6: ×$×'
* Device may be exposed to gases
whose ignition temperature
is higher than this value.
special protection
JODSFBTFETBGFUZOPBSDJOHTQBSLJOH
or hot surfaces
m: encapsulation - sealed arcing devices
or non-arcing
q: sand-filled
nL: nonincendive - limited energy
nA: OPOJODFOEJWFOPOTQBSLJOH
me: encapsulation/increased safety
ATEX Marking (94/9/EC)*
Example:
II
1
Equipment Group
Category
Explosive Atmosphere
Equipment Group
I: Mines
II: Other than mines
5IF"5&9NBSLJOHTBSFJOBEEJUJPOUPUIFTUBOEBSE
;POFNBSLJOHTBOEJOEJDBUFDPNQMJBODFUPUIFOFX
directives.
Category
1: ;POF
2: ;POF
3: ;POF
G
European Community Explosion
Protection Symbol
Explosive Atmosphere
G: Gases/Vapors
D: Dusts
Process Environment
&VSPQFBOSFRVJSFNFOUTDFOUFSFEBSPVOEUIFTBGFUZPG
IB[BSEPVTBSFBFRVJQNFOUUIBUCFDBNFNBOEBUPSZPO
+VMZ"MMFRVJQNFOUFYQPSUFEJOUP&VSPQFBO
NFNCFSDPVOUSJFTNVTUNFFUUIF"5&9IB[BSEPVTBOE
FTTFOUJBMIFBMUIBOETBGFUZSFRVJSFNFOUTGPSBDDFQUBODF
Process Environment
Guide to Hazardous Locations
Ex Marking
Acronyms
IEC and CA (CEC Section 18)
Explosion Protected
ATEX
CA
CEC
CENELEC
Atmosphere Explosible
Canada
$BOBEJBO&MFDUSJDBM$PEF$4"$
European Committee for Electrotechnical
Standardization
EU European Union
IEC International Electrotechnical Commission
I.S. Intrinsic Safety
MSHA Mine Safety and Health Administration
NFPA /BUJPOBM'JSF1SPUFDUJPO"TTPDJBUJPO
NEC® /BUJPOBM&MFDUSJD$PEF® /'1"
US United States of America
Gas Group
I.S. Output
Ex d <JB>**$5
Group
Type of Protection
Temperature Class
"NCJFOUUFNQFSBUVSFSBOHFTPUIFSUIBOTUBOEBSE× C< Ta <×$
NVTUCFNBSLFE
Area Classification
Flammable Material
Present Continuously
US (NEC 505)
®
American
/BUJPOBM Type of
Standard Protection Group Temperature
Class
Permitted Class
$MBTT*;POF"&YE<JB>**$5
Explosion
Gas Group
Protected I.S. Output
Permitted Zone
"NCJFOUUFNQFSBUVSFSBOHFTPUIFSUIBOTUBOEBSE× C< Ta <×$
NVTUCFNBSLFE
Type of Protection
Permitted
Class
PQUJPOBMFYDFQUGPS*4
Explosion proof with I.S. Outputs, Class I,
%JWJTJPO*(SPVQT"#$%5
;POF
;POF
;POF
/&$® ;POF
;POF
;POF
US
IEC/EU
/&$ %JWJTJPO
CEC Annex J
%JWJTJPO
®
US /&$®
CA CEC
4FDUJPO ;POF
/&$®
%JWJTJPO
;POF
;POF
%JWJTJPO
Apparatus Grouping
Temperature Class
PQUJPOBMFYDFQUGPS%JWJTJPO
Flammable Material
Present Abnormally
IEC classification per IEC 60079-10
EU classification per EN 60079-10
US classification per ANSI/NFPA 70 National Electric Code® (NEC®) Article 500 or Article 505
CA Classification per CSA C22.1 Canadian Electrical Code (CEC) Section 18 or Annex J
US (NEC® 500) and CA (CEC Annex J)
Permitted Division
IEC/EU
Flammable Material
Present Intermittently
55PQUJPOBM
Permitted Gas Group
5ZQJDBM
(BT
64/&$®
$"$&$4FDUJPO
&6
*&$
64/&$®
$"$&$"OOFY+
Acetylene
Group IIC
Class I/Group A
Hydrogen
(SPVQ**#)
Class I/Group B
Ethylene
Group IIB
Class I/Group C
Propane
Group IIA
Class I/Group D
Group I*
Mining*
Methane
"NCJFOUUFNQFSBUVSFSBOHFTPUIFSUIBOTUBOEBSE× C< Ta <×$
NVTUCFNBSLFE
*Not within scope of NEC . Under jurisdiction of MSHA. Not within scope of CEC.
®
Temperature Class
EU (Directive 94/9/EC) - ATEX
European
Standard
Type of Protection
Temperature
Class
Group
&YE<JB>**$5
Explosion
Protected
CE Conformity
.BSLJOH
Gas Group
I.S. Output
Explosion
Protection
.BSLJOH
0000
5ZQFPG&YQMPTJWF"UNPTQIFSF
(GPSHBTFTWBQPST
BOENJTU
%GPSEVTUT
II 2 G
*EFOUJGJDBUJPO/VNCFSPG/PUJGJFE#PEZ
Involved in Production Control Stage
$BUFHPSZ GPS;POFPS
GPS;POFPS
GPS;POFPS
&RVJQNFOU(SPVQ*GPSNJOFT
**GPSPUIFSUIBONJOFT
"NCJFOUUFNQFSBUVSFSBOHFTPUIFSUIBOTUBOEBSE× C< Ta <×$
NVTUCFNBSLFE
.BYJNVN
4VSGBDF
5FNQFSBUVSF
64/&$®
$"$&$4FDUJPO
&6
*&$
64/&$®
$"$&$"OOFY+
$
5
5
$
5
5
$
5"
$
5#
$
5$
$
5%
$
5
5
$
5"
$
5#
$
5$
$
5
5
$
5"
$
5
5
$
5
5
valve communication and control
Chemical Compatibility
#
A
A
6
"
A
B
A
"
A
A
FC
B
"
A
A
A
---
"
A
A
U
"
B
A
A
"
A
B
"
A
A
A
B
A
U
"
A
--
Temperatures less than 30° C
1
1
Epoxy
B
U
A
A
A
A
A
A
A
B
A
-U
A
A
A
-B
A
-A
-A
U
Stainless Steel
Epoxy
A
A
A
A
A
B
A
B
A
A
B
B
U
B
B
B
B
U
A
B
A
A
B
A
Polycarbonate
Stainless Steel
B
FC
-FC
FC
FC
-FC
A
FC
A
B
FC
-A
FC
FC
B
B
FC
-----
---
/PFGGFDU3FDPNNFOEFE
Moderate effect
4FWFSFFGGFDU/PU3FDPNNFOEFE
Fusion coating recommended on
polycarbonate
No test data or experience available
U
B
B
A
A
U
#
6
U
"
"
"
U
U
6
6
U
"
B
B
6
FC
FC
FC
FC
-FC
"
#
-#
"
#
B
A
'$
'$
--"
B
A
A
A
A
B
A
B
"
#
B
"
"
"
U
B
"
"
A
#
A
B
A
B
A
A
-A
"
6
-"
"
"
B
A
"
"
-"
A
A
#
"
"
6
U
B
6
B
A
B
B
B
U
'$
-B
"
B
FC
B
A
---
#
A
A
6
B
A
B
B
B
B
"
A
A
"
A
B
B
--A
Aluminum
Polycarbonate
A
A
A
B
B
B
A
B
A
B
B
U
U
U
B
U
B
U
U
B
-A
U
B
Key
"
B
6
FC
Chemical
Methyl chloride
Methyl ethyl ketone
Methylene chloride
Naptha
Natural gas
Nickel chloride
/JUSJDBDJE
/JUSJDBDJE
Nitrous oxide
0JMTBOJNBM
0JMEJFTFM
0JMNJOFSBM
1IPTQIPSJDBDJE
BJSGSFF
Potassium chloride
1PUBTTJVNIZESPYJEF
1PUBTTJVNIZESPYJEF
Potassium phosphate
1SPQBOF-1(BT
Soaps and detergents
Sodium chloride
4PEJVNIZESPYJEF
DBVTUJDTPEB
4PEJVNIZESPYJEF
DBVTUJDTPEB
4PEJVNQIPTQIBUFNPOPCBTJD
Sulfur dioxide
4VMGVSJDBDJE
Tannic acid
Toluol and toluene
Turpentine
Urea
Vinyl Chloride
Water, salt
Process Environment
Chemical
Acetic Acid
Acetone
Acetylene
Alcohol, AmylAlcohol, ButylAlcohol, EhtylAmmonia, liquid
Ammonium hydroxide
Beer
Benzene
Boric acid
Brine
Bromine
Calcium carbonate
Calcium Chloride
Carbon tetrachloride
Chlorine
Chromic acid
Citric acid
Creosote
Ethyl chloride
Ethylene
Ethylene oxide
Fluorine
'SFPOBOEPUIFS
TJNJMBSSFGSJHFSBOU
Gasoline
Heptane and hexane
)ZESPDIMPSJDBDJE
)ZESPHFOHBT
Hydrogen peroxide
Hydrogen sulfide
Isopropyl ether
+FUGVFM+1
Kerosene
Methane
Aluminum
The chemical compatibility reference guide has
been developed to assist you in selecting the
best STONEL products and material options for your
applications. While this chart should assist you in
selecting compatible materials, it is not a substitute
for careful testing of a specific product in your operating
environment. For additional assistance please contact
STONEL technical support.