demystifying equipment design in hazardous locations

DEMYSTIFYING EQUIPMENT DESIGN IN HAZARDOUS LOCATIONS
Rockwell Automation Fair
Houston, TX . November 2013
EQUIPMENT PROTECTION SOLUTIONS
1
OBJECTIVES
• What is a hazardous area?
• NEC 500 North American Standards & Certifications
• Class & Division / Sub Group / Temperature Class
• NEC 505 AEx
• IEC & ATEX Standards & Certifications
• Zones / Protection Concepts / Temperature Class
• Increased Safety Ex e
• Purge & Pressurization Ex p
• Questions & Examples
• Where to get more information
• Hoffmanonline.com
PENTAIR 2
WHAT ARE HAZARDOUS LOCATIONS?
Definition: Areas where flammable liquids, gases, vapors, dusts or fibers are present creating risks for fires and explosions
Oil & Gas
Refining
?
So What? Equipment used in these areas must be specifically designed and installed to prevent explosions
Power Generation
Other Industries include Waste Water Treatment, Chemical, Grain Elevators, Pharmaceutical, Food Processing, Flour Silos, Mills
Hazardous Locations Present in Many Industries and Plants
PENTAIR 3
EXPLOSIVE ATMOSPHERE ‐ DIASTERS
•
•
Refinery in Louisiana: ‐ Explosion June 2013
West Texas Fertilizer Plant
‐ Explosion June 2012
ABC Channel 8 PENTAIR REUTERS/Picture courtesy of Ryan Meador/Handout via Reuters
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PROPERTIES OF EXPLOSIONS
• 3 elements needed for explosion
–Fuel / flammable combustive substance
–Air / Oxygen
–Ignition Source
• All three must to present for combustion!
• Mitigation of any one leads to eliminating the hazard.
Control or eliminate any element prevents explosions
PENTAIR 5
HAZARDOUS LOCATION STANDARDS
Electrical equipment installed in hazardous locations are subject to regulations and standards
IEC Ex
International Electrotechnical Commission
Global standard outside North America and European Union
ATEX
Atmosphere Explosive
Adopts IEC standards into series of directives
North America
Regulations established by NEC, CEC, OSHA and NFPA NEC 500 is most common and used for decades
Law in European Union
Different Standards Depending on Installation Location
PENTAIR 6
HAZARDOUS LOCATION CLASSIFICATION HARMONIZATION
PENTAIR 7
CERTIFICATIONS – NOTIFYING BODY
• Certifications used as global
CSA/CEC
Code
EN
JI
S
NEMA /
NEC
AS/N
ZS
– IEC certificate
– IECEx Scheme certificate
– ATEX certification
– CSA and/or UL certification
• Typical national certifications
– GOST to Russia
– Inmetro to Brazil
– CQST for China
– KOSHA for Korea
– CCE / DGFASLI for India
M
G
PENTAIR 8
GLOBAL HAZARDOUS LOCATIONS ‐ STANDARDS
• Local or Regional standards in addition to IEC / ATEX are common
– They must be addressed
– They can be conflicting
From IEC Ex PENTAIR 9
NEC 500 CLASS / DIVISION
NEC 500 address hazardous locations using Class & Division
‐ Class I Gas
• Sub Groups A (Ac), B (H), C (Et), D (Pro)
• Temperature Class (T‐Ratings) based on ignition Temp T1 (450C)‐T6 (85C)
‐ Class II Dust
• Sub Groups E (Metal), F (Coal), G (Grain)
• Temperature Class ‐ Same
‐ Class III Flying’s and Fibers
• No Sub Groups or Temperature Class
Each Class has Division which describe the hazard level
‐ Division I Hazard exists routinely
‐ Division II Hazard exists sometimes
North America
Regulations established by NEC, CEC, OSHA and NFPA NEC 500 is most common and used for decades
Div 2
Vent
Div 1
Flammable
Liquid
PENTAIR 10
NEC 500 ‐ CLASS I – GAS HAZARDS
CLASS 1
Hazardous Gases
Division 1
Division 2
Constant or expected hazard
Intermittent or unexpected Hazard
Group
Gas Type
A (acetylene)
B (hydrogen)
C (ethylene)
D (propane)
Temperature Rating
Maximum temperature T1
T2
T2A
T2B
T2C
T2D
T3
T3A
T3B
T4
T4A
T5
T6
450C
300C
280C
260C
230C
215C
200c
180C
165C
160C
135C
100C
85C
PENTAIR 11
NEC 500 ‐ CLASS II – DUST HAZARDS
CLASS II
Hazardous Dust
Division 1
Division 2
Constant or expected hazard
Intermittent or unexpected Hazard
Group
Dust Type
F (Coal Dust)
E (Metal Dust)
G (Grain Dust)
Temperature Rating
Maximum temperature T1
T2
T2A
T2B
T2C
T2D
T3
T3A
T3B
T4
T4A
T5
T6
450C
300C
280C
260C
230C
215C
200c
180C
165C
160C
135C
100C
85C
PENTAIR 12
NEC 500‐ CLASS III – FIBERS & FLYING’S HAZARDS
CLASS III
Hazardous Fibers and Flying's
Division 1
Division 2
Constant or expected hazard
Manufactured or Used
Intermittent or unexpected Hazard
Stored and Used
Group
None
Temperature Rating
None
PENTAIR 13
IEC / ATEX ‐ ZONES
•
•
IEC / ATEX address explosive hazardous locations using this systems
• Group I
Mining
• Methane and Dust (Firedamp)
• Temperature Rating T1‐T6
• Group II Gas, Vapors, & Mists
• Gas IIA, IIB, IIC
• Temperature Rating T1‐T6
• Group III Dusts
• Dust IIIA, IIIB, IIIC
• Temperature Rating T1‐T6
ZONES
• Gas
Dust
• ZONE 0
20
• ZONE 1
21
• ZONE 2
22
PENTAIR Global and EU
Regulations established primarily by European Union Presence during
normal operations
Continuous
presence
Presence just
in case of failure or
abnormal operations
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IEC / ATEX ‐ ZONES

According to European Directives 94/9/EC (ATEX), IEC 60079‐10, EN 60079‐10 and NEC 505, hazardous environments are classified, relating to the presence probability of flammable substances, in ZONES:

Zone 0
(Gas presence > 1000 hours/year)


Area where an explosive gas mixture is present continuously, for long period or frequently
Zone 1 Continuous presence
{Dust 20 similar}
Presence during normal operations
{Dust 21 similar}
(Gas presence 10 ‐ 1000 hours/year)


Area where an explosive gas mixture is likely to occur under normal operations Zone 2
{Dust 22 similar}
(Gas presence < 10 hours/year)

PENTAIR Area where an explosive gas mixture is unlikely to occur (or occur only under abnormal conditions)
Presence just
in case of failure or abnormal operations
15
METHODS OF PROTECTION CONCEPTS
• IEC / ATEX has protection concepts
• Ex {e, nA, d, nC, q, ia, ib, ic, ……}
• These are accepted methods approved for hazardous locations
• There are also symbols of each of these concepts
• Today we will discuss Ex e and Ex p in detail
• Each method goal is to address one side of the triangle
Ex e Increased Safety
PENTAIR Exclusion, Containment, Energy Limitation
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IEC / ATEX – ZONE SYSTEM
Explosive Atmosphere
Ex
Symbol For ATEX Protection Method Concept
EX {e, p, ia, d, m, o, q, nR, s, etc.}
Equipment Group
1 – Mining, 2 – Gas, 3 ‐ Dust
Environment
G‐ Gas, D‐ Dust
Apparatus Group Mines
Apparatus Group Gases
Methane (Fire damps)
I
Gas, Vapors, & Mists
II
IIA(propane), IIB (ethylene), IIC (hydrogen)
Apparatus Group Dust
Dust
III
IIIA Fibers & Flyings, IIIB Non‐conductive Dusts
IIIC Conductive Dusts
Temperature Rating
T1‐ T6
PENTAIR T1
T2
T3
T4
T5
T6
450 °C
300 °C
200 °C
135 °C
100 °C
85 °C
17
NEC 505 ‐ OVERVIEW
• AEx e relates to NEC 505 where areas are classified by Zone vs Division
– NEC Zones and IEC/ATEX Zones do not cross
– A Division area cannot house Zone equipment
– There are cases where Division equipment can be used in Zone
• Division 1 encompasses both Zone 0 and Zone 1
– This is why NEC 500 and NEC 505 Area Classifications are not interchangeable
PENTAIR 18
IEC / ATEX ZONE CLASSIFICATION
PENTAIR 19
NEC vs. ATEX/IEC
• There is a broad overlap between NEC and the ATEX/IEC Zone system. The Zone system divides Class 1 Division 1 locations into two zones. They are not interchangeable!
• This provides different methods of protection, for example in zone 0 intrinsically safe concepts would be used, while in zone 1 a flameproof enclosure would be applied.
• The majority of applications for our enclosures in hazardous locations in North America are div 2, correspondingly increased safety enclosures are typically used in zone 2 applications.
Frequency of Occurrence
Class & Division
Zone
Continuous
Class 1 Division 1
Zone 0
Zone 1
Intermittent, Periodically
Abnormal Occurrence
Class 1 Division 2
Div 2
Vent
Zone 2
Zone 2
Div 1
Red Area = Zone 0
Yellow Area = Zone 1
Yellow and Red Area = Division 1
Gray Area = Division 2 or Zone 2
PENTAIR Zone 0
Div 1
Zone 1
Flammable
Liquid
20
NEC AND IEC / ATEX HAZARDOUS LOCATION
Classification of a hazardous area is dependent on the length of time the hazard is present. The charts below highlight the differences between the NEC Class and Division system and the ATEX/IEC EX Zone system.
NEC ATEX / IEC
Zone 0
Division 1
Zone 1
Risk
Risk
Division 2
Zone 2
Not
Not
Classified
Classified
1 hr per
year
10 hrs per
year
Duration of time the gas is present
PENTAIR 1 hr per
year
10 hrs per
year
1000 hrs
per year
Duration of time the gas is present
21
GAS CLASSIFICATION NEC AND IEC / ATEC
•
•
•
The North American code breaks gasses into four groups, IEC uses only three.
The auto ignition temperatures when combined with the duration and the likelihood of combustion are all key considerations for the hazardous rating.
Designers need to take a number of factors into consideration, ambient temp, electrical load, environmental conditions. These considerations will help determine the rating applied to the application. PENTAIR Typical Gas
Class/Division Gas
Groups
Zone Gas Groups
Acetylene
T2
A
II C
Hydrogen
T1
B
Ethylene
T3
C
II B
Propane
T1
D
II A
Note: The lower the auto ignition temperature the more hazardous the environment. A and IIC have the lowest auto ignition temperature. Also reversed scale between NEC and IEC / ATEX. A & B {NEC} corresponds to C {IEC / ATEX}
22
TEMPERATURE CLASSIFICATION
•
•
•
Temperature Classification (T‐Rating) determines the maximum surface temperature of the enclosure (Populated with equipment) to prevent ignition of the gas.
Equipment used in applications in the range from ‐20oC to +40oC are considered to be in the standard range and do not require special classification. All other ranges must be indicated on the product.
Whole T ratings between IEC, ATEX, NEC 505 are the same as NEX 500.
PENTAIR North American
Temperature Code
IEC Ex/ATEX/NEC 505
Temperature Code
Maximum
Temperature
oC
oF
T1
T1
450o C
842o F
T2
T2
300o C
572o F
T2A
280o C
536o F
T2B
260o C
500o F
T2C
230o C
446o F
T2D
215o C
419o F
200o C
392o F
T3A
180o C
356o C
T3B
165o C
329o C
T3C
160o C
320o C
135o C
275o C
120o C
248o C
T3
T4
T3
T4
T4A
T5
T5
100o C
212o C
T6
T6
85o C
185o C
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WHAT IS INCREASED SAFETY? Ex e

In both IEC Ex (Global) and ATEX Directive (European Union) there are (9) Protection Concepts that can be used in various hazardous location applications.
 Final assembly of the system must be Certified by a Notifying Body!
 Sum of parts – Not Certified
 Can be used in Zone 1 and 2 only
 Increased Safety, Ex e, is one of these
Protection Concepts
 Limits the internal components to non‐
arcing and sparking
 Limits the maximum heat rise of the components and associated wires to maximum heat rise relative to rated temperature class
Ex e Increased Safety
PENTAIR 24
INCREASED SAFETY Ex e BACKGROUND – WHY?
• Why were Ex e enclosures developed!
– To reduce costs – avoid the need to use heavy cast Flame Proof (Ex d) enclosures
– Lower material and labor cost to install and maintain
– To provide for terminal applications that are easier to define, restrict, and control
– What goes into a Ex e enclosures is strictly controlled and all assemblies must be reviewed & Certified
– For many years Europe has used this concept with success
– Proven track record
PENTAIR 25
TYPICAL Ex e ENCLOSURE ATTRIBUTES
• Ingress Protection against moisture and dust
•
•
•
•
•
•
– Minimum of IP54 / Type 12, typically IP66 / Type 4x performance
– Gasket that withstands a 28‐day high heat and humidity aging test and ‐
40 degree cold cycle test
Internal/external grounding provisions
– All sealing components on latches, ground, gland plates as well
Robust Mechanical Design
– Impact tests – withstand and still perform
Zone 1 concept for circuits <10kV with known thermal rise
“Schedule Drawings” of design on file with Notified Body
Manufacturing Quality Audits and Traceability of manufactured product
3rd party Certification by a Notified Body
PENTAIR 26
TYPICAL Ex e ENCLOSURE LIMITATIONS
•
•
•
•
Enclosures (Empty) are certified as Component (U)
• Will require recertification to evaluate final assembled or populated product
No arcing or sparking components
• Restricted to Increased Safety (Ex e); Non‐
arcing/non‐incendive (Ex nA) or Intrinsically Safety (Ex i) components
• No fuses, switches, breakers, PCB, etc.
• No Electronics
Requires Increased Safety cable glands
• All cable entries must used approved devices!
Thermal Rise must be known
• Max surface temperature
Once the enclosure is fully integrated, it must be submitted for certification to a notifying body!
PENTAIR 27
LOCAL CERTIFICATIONS / BASED ON IEC or ATEX
• Local certifications are mainly obtained based on IEC or ATEX
Local market
PENTAIR 28
TEMPERATURE CONSIDERATIONS
•
When applying a T rating to a assembled or populated enclosure the ambient temp is a critical consideration.
• Auto‐ignition ratings for the gas environment will limit the surface temperature of the enclosure, the components inside may further increase the surface temperature.
• So, can a T6 populated enclosure be used in a T3 application? The answer is, it depends –
questions to ask:
•
•
•
PENTAIR What is the ambient temp?
How much heat dissipation is present?
Can the materials used withstand the heat?
• The operating temperatures of he cabinet may determine the possible T rating
Ambient Temp
Surface Temp
Temp of installed components
Standard Ambient Temp Range –
Marking not required
–20°C to +40°C
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IEC / ATEX Ex e ‐ SUMMARY
EX e = Increased Safety
• IEC / ATEX protection concept
Must be certified as an assembly • Component or U certifications speeds up the process significantly! Saves time and money!
• All penetrations must be made by approved EX e devices
T –ratings apply to assemblies or systems only
• Enclosure operating temperatures may be impacted
• Environmental ambient temperatures may impact Enclosures requirements
• Can made of steel, stainless steel, and composite
• Minimum impact strength requirements
• Bonding & Ground requirements
• Gasket testing (temperature and aging)
ATEX although nearly the same as IEC requires certification per ATEX by a Notified Body – Local Certifications
PENTAIR PURGE & PRESSURIZATION Ex p(x, y, z)
•
What is Purge and Pressurization?
• Enclosure is purged of hazardous Gas or clean of hazardous Dust
• Once purged and cleaned, the enclosure is then pressurized to keep out hazardous Gas and Dust
• Allows for standard sealed enclosures to be used in hazardous locations
ADVANTAGES
• May be only practical solution especially for large equipment needing large enclosures
DISADVANTAGES
• Requires protective gas supply (Air is used commonly)
• Requires other protection methods to operate
• Powered maintenance is not permitted PENTAIR 31
ENCLOSURE REQUIREMENTS
Basic Needs
• A sealed Type 12 or IP 54 Enclosure
Not all of these will work – leakage
Larger cabinets are most often use Purge and Pressurization
• Why – Costs to use other concepts are impractical or expensive
What to look for:
• Robust vault Style latch systems
• Heavy gauge construction
• Limited Doors, Covers, etc. (Modular)
• Premium gasket (fully glued joints or no joints)
PENTAIR IMPORTANCE CONSIDERATIONS
All Cable entry points must sealed
• Too much leakage will prevent pressurization
• All conduits must be sealed!
Clean and reliable gas / air supply
• Number 1 reason for issues is dirty air
• Air supply must be dry
• If leakage is minimal, little air supply is needed to sustain pressurization
• Avoid pressure spikes or too low of pressure
Doors and cover must be fully secured
• All latches engaged – extra mid door latching is common to reduce / eliminate leakage
PENTAIR PURGING PROCESS – NFPA 496
THIS IS REQUIRED FOR DIVISION 1 AND 2 AREAS
CLASS I: HAZARDOUS GAS
CLASS II: COMBUSTIBLE DUST
1. Initial state no pressure, equipment is off, unsafe
1. Initial state no pressure, equipment is off, unsafe
2. Enclosure must be purged 4 times it volume to assure inside is safe
2. Inside enclosure must be physically cleaned of all combustible material
3. After purging, pressure must be maintained for safe condition
3. Enclosure is sealed and pressure must be maintained for safe condition
4. Equipment inside enclosure can be energized
4. Equipment inside enclosure can be energized
AT ANY TIME IF PRESSURE IS LOST, NECESSARY ACTION MUST BE TAKEN
PENTAIR 496
34
PURGING PROCESS IEC / ATEX Ex p
In both IEC Ex (Global) and ATEX Directive (European Union) there are (9) Protection Concepts that can be used in various hazardous location applications.
Purge and Pressurization, Ex p, is one of these Protection Concepts
– Eliminates integral Gas and Dust hazardous conditions (Purge)
– Keeps out Gas and Dust (Pressurization)
PENTAIR 35
TYPES OF PURGING DEVICES
TYPE “Y” Reduces classification within enclosure from Division 1 to Division 2
TYPE “Z” Reduces classification within enclosure from Division 2 to non‐hazardous
Many Purge and Pressurization systems are being dual rated for Y and Z! Application determine is Y or Z!
TYPE “X” Reduces classification within enclosure from Division 1 to non‐hazardous
PENTAIR 36
OPERATION CONSIDERATIONS
Differences Between Types X, Y and Z
TYPE Y AND Z
TYPE X
• Pressure loss – alarm must sound if • Pressure loss – must remove power to enclosure (Automatically)
power is not removed
• Manual timing of purging allowed
• Flow is measured at inlet to enclosure
PENTAIR • Timer required for Purging (Automatically)
• Flow based on measurement at outlet
37
PURGE & PRESSURIZATION ‐ SUMMARY
NFPA 496 (North America)
• Easier to do (Self Certifying)
IEC / ATEX Ex p (x, y, z,)
• Requires each unique finished assembly (integrated enclosure) to be analyzed by a notifying body for conformance and certification
Allows for standard off the shelf enclosure use
• Type 12 / IP 54 minimum
Type Y & Z
• Local alarm and signal for remote alarm
Type X
• Power must shut off when pressure is lost
PENTAIR Where to get more information!
More Information?
‐
Call Local Hoffman representative
‐ Contact Hoffman Customer Service department
• 763‐422‐2211
‐ Go to Hoffman website
• www.hoffmanonline.com
PENTAIR 39
SUMMARY QUIZ
1.
2.
3.
4.
5.
PENTAIR Can a Class 1 Division 1 be used in a Class 1 Division 2
• Yes – Division 1 is a higher hazard area and can be used in a lower Division 2 hazard area (Need to match Gas type as well)
Can a Class 1 Division 1 be used in a Class 2 Division 1
• No – You must remain in the Class
If all the Parts (U components) are rated for IEC Ex e, can the final assembly (Populated) enclosures can be installed in to the hazardous area?
• No – All IEC & ATEX Ex e must have the entire integrated (populated) enclosure tested by a governing body (Test Lab) to certify that it conforms to standards
Does an empty (U Component) enclosure have a Temperature Class (T Rating)?
• No – only a complete assembly (populated) enclosure has a T Rating. T Rating is the max surface temperature that the enclosures will have while it is in service.
• The difference between the min / max operating temperature of the enclosure is not directly related to the T Rating. The enclosure or component operating temperature must be lower than the T –Rating. The min temperature is often more concerning which is not related in any way to the T rating.
I have a requirement for a T‐Rating of T2 =< 300C. Can I use a solution that has a T‐Rating or T4 =<135C?
• Yes, T4 has T‐rating (Temperature Class) = < 135C which has a lower surface temperature max temp than that of T2 =<300C. The higher the T ‐rating number the lower the surface temperature . The lower the temperature rating the lower the ignition temperature and greater the hazard.
40
DEMYSTIFYING EQUIPMENT DESIGN IN HAZARDOUS LOCATIONS
Presented by:
Brian Mordick
Senior Product Manager
763.422.2168
brian.mordick@pentair.com
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