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Plastic/Polycarbonate Enclosures Technical Specifications


An enclosure is a housing constructed to provide a degree of protection from accidental contact with the enclosed equipment and external environmental conditions. Polycarbonate enclosures are designed for indoor and outdoor use, but are small and light-weight, and provide a high tolerance to harsh environments. They come in multiple sizes and styles that fit small to mid-sized equipment.

Click here to Shop Now or if you have any questions and need assistance choosing a polycarbonate enclosure for your application please contact us at (888) 886-8185.


ABS/Polycarbonate Enclosures - About
ABS/Polycarbonate Enclosures - Materials
ABS/Polycarbonate Enclosures - Gasket Materials
ABS/Polycarbonate Enclosures - Chemical Resistance
ABS/Polycarbonate Enclosures - Flammability Specifications
ABS/Polycarbonate Enclosures - Enclosure Ratings
ABS/Polycarbonate Enclosures - IP and IK Ratings
ABS/Polycarbonate Enclosures - RoHS Compliance
ABS/Polycarbonate Enclosures - Sources of Standards


About

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Polycarbonate and ABS Enclosure Materials

Thermoplastic enclosures are made of polycarbonate (PC) or acrylnitrile-butadiene-styrene (ABS) materials. High impact-resistant polystyrene (PS) enclosures are available to order.

Polycarbonate is an amorphous thermal plastic material whose high heat resistance and excellent physical properties make it an ideal material for enclosures. Polycarbonate can withstand a wide range of temperature fluctuations and its good electrical properties are unaffected by humidity. As a self-extinguishing material, polycarbonate requires no protective coating.

ABS is another amorphous thermal plastic material with good physical properties and high resistance to chemical attack. It is an ideal cost effective material. ABS materials are less protective against UV rays if directly exposed. However, it can be used if protected against weather influences.

UV Resistance of Transparent and Grey Polycarbonate Enclosures

Virtually all plastic materials are susceptible to degradation under the influence of U.V. radiation, but the quality polycarbonates used in Fibox enclosures show high durability in this respect. In European latitudes, Fibox enclosures can be used, without hesitation, in outdoor applications. Over the years a slight discoloration, especially of the transparent cover material, will occur. If this must be avoided, a sun roof is recommended. In tropical latitudes, the grey coloured material still performs with only some discoloration. This is due to the TiO used in the grey pigmentation in order to UV-stabilize the material. The transparent material, however, which absorbs the U.V. radiation throughout the material, will in due time (some years) not only turn yellowish, but the high impact resistance will decrease (see below). But more than lowering the impact resistance, the transparent materials allow the UV-radiation to detonate the components mounted inside the enclosure. The polycarbonates used in Fibox enclosures have been tested and approved by Underwriters Laboratories, Melville, N.Y. USA, in conformity with standard UL 508 par. 34; 16-22. This standard specifies testing 720 hours in 'Weatherometer' (intensified UV light combined with water spray). After testing the materials must retain 85% of the original values with respect to tensile and flexural strength, impact resistance, flammability, and glow wire ignition.

Materials

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Size is normally the first and the most dominant criterion when looking for the right enclosure for a specific application. Enclosure performance, i.e., material performance, is usually the second property considered. The following list of benefits and drawbacks indicates the basic differences between the various enclosure materials.


Polycarbonate (PC) or Glassfibre Reinforced (PC+GLAS)

Benefits:
  • Very high impact resistance
  • Also available in transparent form
  • Easy machining with normal tools
  • High lP rating
  • Clean attractive finish
  • Wide operating temperature range
  • Self-extinguishing
  • Good resistance to chemical attack
  • Low weight
  • Good UV resistance
  • Excellent insulating properties
  • Cost-effective material for harsh environments


Drawbacks:
  • No EMC shielding

ABS (Acrylnitrile-butadiene-styrene)

Benefits:
  • Easy machining with normal tools
  • Easy colouring through pigmentation
  • Low weight
  • Good resistance to chemical attack
  • Excellent insulating properties

Drawbacks:
  • Slightly lower impact resistance compared with PC
  • Slightly lower operating temperature range compared with PC
  • Slightly lower UV resistance compared with PC. Recommended for outdoor use if protected against weather influences
  • Not available in transparent form
  • No EMC shielding

Fiberglass (GRP)

Benefits:
  • Excellent record of resistance to corrosion and chemical attack
  • High impact resistance
  • Rigid construction
  • High weather resistance
  • Wide operating temperature range
  • Fire resistant
  • Good insulating properties


Drawbacks:
  • More expensive than PC
  • Cannot be machined using standard tools
  • No EMC shielding
  • Heavier than other plastic enclosures


Gasket Materials

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Comparison

Gaskets play an essential role in enclosure protection. In the long run, the IP rating and its reliability depend mainly on the properties of the gasket used in the enclosure. Key performance factors of a gasket are its compression set and proper fit in the gasket groove. The best general purpose gasket material is polyurethane which has an exceptionally low compression set. When accurately foam injected, the polyurethane gaskets stay tightly in the right place. EPDM material provides the best protection against the most popular industrial chemicals. However, it is wise to check the effect of a chemical on each gasket material since the chemical resistance of gasket materials varies greatly.

In some cases the performance of an enclosure can be modified by changing its gasket. The degree of protection depends on the material and the cross-section profile of the gasket. In addition to the cross-section profile of the gasket, there is the cross section of the gasket's contact with the surfaces of the enclosure's bases and covers. If the cross-section structures and manufacturing accuracy of an enclosure are not top quality, the IP rating will remain low even when equipped with a good gasket. When choosing gasket material, compare the elasticity properties of different materials and how these properties are affected by cold and heat, or by contact with various chemicals. An important factor is that both the enclosure and gasket must withstand the same chemicals in order to reach a safe resistivity.

Table 1 includes some commonly-used physical properties of the gaskets. Note that the chemical resistances in the box and in Table 2 are only rough generalizations to give you some clues to gasket material behavior. The resistance of each chemical should be checked separately. For additional information, please contact us.


Physical Properties Comparison (Table 1)

Property Unit PUR EPDM Neoprene Silicon
Temperature range °C -50 - +130 -50 - +120 -40 - +100 -60 - +170
Tensile strength Mpa 0.4 13.0 8.0 9.4
Elongation at break % 110 300 250 540
Hardness Shore A 12 65 66 52
Density g/cm3 0.33 1.12 1.6 1.15
Compression set % 5 20 35 14

Chemical Resistance Comparison (Table 2)

Chemical Performance PUR EPDM Neoprene Silicon
Neutral salts **** **** **** ****
Acids, low concentrations *** **** *** ***
Acids, high concentrations * *** * *
Alkalis, low concentrations **** **** **** ***
Alkalis, high concentrations *** **** *** *
Petroleums * * *** *
Hydraulic oils **** * *** *
Alcohols *** *** **** ****
Cooling fluids *** *** *** ****


PUR Gaskets (Polyurethane)

PUR differs from other gasket materials as it is shaped by special foam injection in the enclosure's gasket groove (usually in the cover). In this way, the gasket sticks permanently and securely to the enclosure. This ensures a reliable IP rating. PUR gaskets have an extremely low permanent compression set (the amount of residual displacement after the compressing load has been removed). In addition, the mechanical properties remain stable in -50 to + 130 °C temperature range. The material can easily withstand various weather conditions.

PUR gaskets are resistant to fats, oils, and acids, but they do not withstand strong alkalis.

PUR gaskets can only be used when the gasket groove is round and wide enough. Some Fibox enclosures cannot be equipped with PUR gaskets because of their small size, or sharp-edged groove shape. In those cases EPDM is used.


EPDM Gaskets (Ethylene-Prophenediene-Monomer)

These gaskets have a very low permanent compression set and are resistant to cold and heat in a wide -50 to +120 °C temperature range. Ozone, oxygen and UV radiation have little effect on EPDM gaskets which makes them suitable for outdoor conditions.

Due to their chemical structures, EPDM gaskets resist polar solvents well. The gasket material is suitable for application environments where tolerance is required against water, salt fluids, steam, alcohols, glycols, phosphate based esters or weak acids, and weak alkalis. EPDM gaskets are not resistant to many oils and hydrocarbon based solvents.


Weather-Resistant NEOPRENE Gaskets (Chloroprene Rubber)

Mechanical properties of neoprene material are good and its permanent compression set is fairly low. Temperature resistance is from -40 to +100 °C. Neoprene is self-extinguishing with excellent weather resistance properties such as sunlight, oxygen and ozone which do not affect the material.

Neoprene gaskets are resistant to oils, fats, hydrocarbons and alcohols, although some of these may cause limited material swelling.


Temperature-Resistant Silicone Gaskets

Silicone gaskets have an exceptionally wide -60 to + 170 °C temperature resistance range. They are primarily used in extremely cold or hot environments. Silicone is resistant to alcohols and ketones, but strong acids and strong alkalis have dissolving effects on the material.



Chemical Resistance

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Enclosure Material Polycarbonate ABS FRP Stainless Steel Steel
Acetic Acid (10%) S L S U U
Acetone U U U S S
Aluminum Chloride (10%) S S S S U
Aluminum Sulfate (10%) S S S S U
Ammonia Gas     L S S
Ammonium Chloride S S L M U
Ammonium Hydroxide (10%) U M L S U
Ammonium Nitrate (10%) U   L S S
Ammonium Phosphate (10%) S S S S U
Ammonium sulfate   S S M U
ASTM #1 Oil M L   S S
ASTM #3 Oil M L   S S
Axle Grease M L   S S
Boric Acid (10%) S S S S U
Calcium Chloride (10%) S M S L L
Calcium Hydroxide (10%) S   U M S
Carbolic Acid (25%) Phenol U U L M U
Carbon Tetrachloride U U S M U
Chlorine (water) 5-10 ppm S S S M  
Chrome Plating Solution S L   U U
Chromic Acid   S S M U
Citric Acid (10%) S U S S U
Copper Sulfate       M U
Cutting Fluid (Norton 205) S L   S S
Ethyl Alcohol M M M S S
Ethylene Glycol S S S S S
Ferric Chloride S S S U U
Formaldehyde   S S S S
Formic Acid S U L S U
Fuel Oil (#2) S U S S S
Gasoline   U S S S
Glycerin   L S S S
Hydraulic Brake Fluid U U   S S
Hydraulic Oil M U S S S
Hydrochloric Acid (10%) S S L U U
Hydrofluoric Acid (20%) M L S U U
Hydrogen Peroxide   L S M M
Hydrogen Sulfide   M   L U
Isopropyl Alcohol S M   S S
Kerosene M U S S S
Lacquer Thinner U U   S L
Liquid Dish Soap (10%) S   S S S
Lubricating Oils   M S S S
Magnesium Chloride (10%) S M S U U
Magnesium Hydroxide (10%) S M M S S
Methyl Ethyl Ketone   U S S S
Methylene Chloride U U U S S
Mineral Spirits M U S S S
Motor Oil (10 weight) S L   S S
Nitric Acid (10%) L M M L L
Perchlorethylene U U   S S
Phosphoric Acid (25%) S M U    
Phosphoric Acid (50%) S M U U U
Potassium Carbonate (10%) S S L M L
Potassium Chloride (25%) S S S S S
Potassium Hydroxide (25%) U S L S S
Potassium Nitrate (10%) S S S S S
Potassium Sulfate (10%) S S S S S
Soap (lgepal) 10% S S S S S
Sodium Bicarbonate (10%) S S S S L
Sodium Bisulfate (10%) S S   U U
Sodium Chloride (25%) S S S M U
Sodium Hydroxide U M U M M
Sodium Hypochlorite S S L L U
Sodium Nitrate (10%) S   S M M
Sodium Phosphate (10%) S S L M U
Sulfuric Acid (25%) S S U U U
Tannic Acid (10%) S S   M L
Toluene U U   S S
Trichloroethylene   U U M M
Trisodium Phosphate   M   M  
Turpentine S U S S S
Vegetable Oils   S S S S
Xylene U U S M M
Zinc Chloride M S   M U
  • S= Satisfactory and completely unaffected
  • M= Moderate resistance, surface change in glass but properties remain
  • L= Limited resistance/some chemical attack over time. Exposure should be limited to occasional fumes or light splashing
  • U= Unsatisfactory. Severe attack in a short time


Flammability Specifications

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UL 94 Flammability Classification Tests for Plastic Materials

UL 94 is the standard applied by the American Underwriters Laboratories for the testing of the flammability and fire safety of plastic materials used in devices and appliances. The UL 94 HB (Horizontal Burning) tests the burning of a horizontal plastic specimen and the most demanding UL 94V (Vertical Burning) tests the burning of a vertical plastic specimen. Precise details of the equipment, conditions and test systems to be used can be found in the UL 94 standard.


UL 94 HB - Horizontal Burning Test
UL 94 HB Horizontal Burning Test

The length of the test specimen is 5" (127 mm) and width 0.5" (12.7 mm). The test sheet cannot be more than 0.5 (12.7 mm) thick. Lines are marked on the sheet at the 1" and 4" locations. The sheet is fixed horizontally at one end and tilted 45 degrees in the direction of the width, as shown in the diagram. The burner used is adjusted so that it forms a 1" long blue flame. The flame is directed at an angle of 45 degrees to the front edge of the plastic sheet so that about 1/4 of the test specimen’s front edge is in the flame. The flame is applied for 30 seconds, after which it is removed. If the test specimen burns to the 1" line before 30 seconds have passed, the flame is removed immediately. The test is carried out on three test sheets.

The material under investigation is classified as UL 94 HB if after the removal of the flame:

  1. The speed of burning does not exceed 1.5" (38.1 mm) per minute when the test specimen thickness is 0,120-0.500" (3.05-12.7 mm) OR
  2. The speed of burning does not exceed 3.0" (76.2 mm) per minute when the thickness of the specimen is less than 0.120" (3.05 mm) OR
  3. Burning finishes before the flame reaches the 4" line


UL 94: V-O, V-1 and V-2 Vertical Burning Tests
UL 94 V Vertical Burning Test

The test specimen length is 5" (127 mm) and width 0.5" (12.7 mm). The sheet to be tested can not be more than 0.5’ (12.7mm) thick. The sheet is fixed 1/4" from the upper end in the vertical position. A metal mesh covered with surgical cotton is positioned 12" (305 mm) beneath the test sheet. The flame of the burner used is adjusted so that is forms a 3/4" blue flame. The flame is directed from below at the lower edge of the plastic sheet at a distance of 3/8" (9.5 mm). The flame is applied for 10 seconds, after which it is removed. The burning time of the test specimen is recorded. Immediately the burning stops the flame is reapplied for 10 seconds. After removal of the flame the burning time and afterglow time is again noted. The entire test is carried out on five different test specimens.

The material tested is UL 94 V-O classified if:

  1. None of the five test specimen burn for over 10 seconds at any time when the burner flame is removed.
  2. The total burning time of the 10 ignition test does not exceed 50 seconds.
  3. No test specimen burns either with a flame or afterglow to the clamp.
  4. No burning drops should fall which would cause the cotton underneath to ignite from any test specimen.
  5. The afterglow burning of no test specimen exceeds 30 seconds.
The material tested is UL 94 V-1 classified if:
  1. None of the five test specimen burn for over 30 seconds at any time when the burner flame is removed.
  2. The total burning time of the 10 ignition test does not exceed 250 seconds.
  3. No test specimen burns either with a flame or afterglow to the clamp.
  4. No burning drops should fall which would cause the cotton underneath to ignite from any test specimen.
  5. The afterglow burning of no test specimen exceeds 60 seconds.
The material tested is UL 94 V-2 classified if:
  1. None of the five test specimen burn for over 30 seconds at any time when the burner flame is removed.
  2. The total burning time of the 10 ignition test does not exceed 250 seconds.
  3. No test specimen burns either with a flame or afterglow to the clamp.
  4. Only such burning pieces may fall from the test specimen, which burn only momentarily, and of which some ignite the cotton underneath.
  5. The afterglow burning of no test specimen exceeds 60 seconds.

UL 94 5V - Vertical Burning Test
UL 5V Vertical Burning Test

The length of the test specimen is 5" (127 mm) and the width 0.5 (12.7 mm). The test sheet shall not be more than 0.5" (12.7 mm) thick. Flammability classification is granted for specific thickness intervals, for which both the maximum thickness and minimum thickness sheet must be tested. The test sheet is fixed 1/4" from the upper end in the vertical position. The flame of the burner used is adjusted so that it forms a 5" flame whose blue heart is 1.57" (40mm) long. The flame is directed from below at the corner of the plastic sheet at a distance of 1". The flame is applied for 5 seconds, after which it is removed for 5 seconds. This is repeated five times. The entire test is carried out on five test specimen.

The material tested is VI 94-5V classified if:

  1. No test specimen burns with a flame or afterglow for more than 60 seconds after the fifth ignition.
  2. No material drops from the test specimen.


Enclosure Ratings

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The National Electrical Manufacturers Association (NEMA) is a U.S. Manufacturers Organization that actively promotes standardized product specifications for electrical apparatus.

NEMA performance criteria and test methods are used by Underwriters' Laboratories as guidelines for investigation and listing of electrical enclosures.

Approximate IP equivalents in parentheses.


NEMA 1: Indoor use primarily to provide a degree of protection against contact with the enclosed equipment and against a limited amount of falling dirt. (IP30)
NEMA 2: Indoor use to provide a degree of protection against limited amounts of falling water and dirt. (IP31)
NEMA 3: Outdoor use to provide a degree of protection against windblown dust, rain, and sleet; undamaged by the formation of ice on the enclosure. (IP64)
NEMA 3R: Outdoor use to provide a degree of protection against falling rain and sleet: undamaged by the formation of ice on the enclosure. (IP32)
NEMA 3S: Outdoor use to provide a degree of protection against windblown dust, rain and sleet; external mechanisms remain operable while ice laden.
NEMA 4: Indoor or outdoor use to provide a degree of protection against splashing water, windblown dust and rain, hose directed water; undamaged by the formation of ice on the enclosure. (IP66)
NEMA 4X: Indoor or outdoor use to provide a degree of protection against splashing water, windblown dust and rain, hose directed water; undamaged by the formation of ice on the enclosure, resists corrosion. (IP66)
NEMA 6: Indoor or outdoor use to provide a degree of protection against the entry of water during temporary submersion at a limited depth; undamaged by the formation of ice on the enclosure.
NEMA 6P:  Indoor and outdoor use to provide a degree of protection against the entry of water during prolonged submersion at a limited depth.
NEMA 11: Indoor use to provide by oil immersion a degree of protection of the enclosed equipment against the corrosive effects of corrosive liquids and gases.
NEMA 12,12K: Indoor use to provide a degree of protection against dust, falling dirt and dripping noncorrosive liquids. (IP65)
NEMA 13: Indoor use to provide a degree of protection against dust and spraying of water, oil and noncorrosive coolants. (IP65)


IP and IK Ratings

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Ingress protection class of enclosures is given in form of IP classification, a two digit coding which is shown below. Fibox has tested the enclosures according to IEC 529 or EN 60529. The latter requires the second digit to be tested from class 6 upwards separately to each level of class, thus the double marking IP 66 / IP 67 indicates that the actual tests have been made for both levels.

The European standard for enclosures, EN 50298 also includes IK impact test. This test is described in EN 50102. The data for impact resistant is available for each individual Fibox enclosures.


First IP Number - Protection against solid objects Second IP Number - Protection against liquids IK Code - Protection against mechanical impacts
IP TEST IP TEST IK TEST
0IP 0 Rating no protection 0IP 0 Rating no protection 00IK 00 Rating no protection
1IP 1 Rating protected against solid objects over 50 mm e.g. accidental touch by hands 1IP _1 Rating

protected against vertically falling drops of water

01
-
05
IK 01-05 Rating

impact < 1 joule

2IP 2 Rating

protected against solid objects over 12 mm e.g. fingers

2IP _2 Rating

protected against direct sprays of water up to 15° from the vertical

06IK 06 Rating

impact 1 joule

3IP 3 Rating

protected against solid objects over 2,5 mm (tools + small wires)

3IP _3 Rating

protected against sprays to 60° from the vertical

07IK 07 Rating

impact 2 joule

4IP 4 Rating

protected against solid objects over 1 mm (tools + small wires)

4IP _4 Rating

protected against water sprayed from all directions - limited ingress permitted

08IK 08 Rating

impact 5 joule

5IP 5 Rating

protected against dust - limited ingress permitted (no harmful deposit.)

5IP _5 Rating

protected against low pressure jets of water from all directions - limited ingress permitted

09IK 09 Rating

impact 10 joule

6IP 6 Rating

totally protected against dust

6IP _6 Rating

protected against strong jets of water e g for use on ship decks - limited ingress permitted

10IK 10 Rating

impact 20 joule

    7IP _7 Rating

protected against the effects of immersion between 15 cm and 1 m

   
    8IP _8 Rating

protected against long periods of immersion under pressure

   


Sources of Standards

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National Electrical Manufacturers Association
www.nema.org
NEMANational Electrical Manufacturers Association
  • 1300 N.17th St., Suite 1752, Arlington, VA 22209
Underwriters Laboratories Inc.
www.ul.com
ULUnderwriters Laboratories Inc.
  • 2600 N.W. Lake Rd., Camas, WA 98607-8542
Canadian Standards Association
www.csa.ca
CSACanadian Standards Association
  • 5060 Spectrum Way, Suite 100, Mississauga, Ontario L4W 5N6 CANADA
Joint Industry Council c/o AMT - The Association for Manufacturing Engineering
www.amtonline.org
JICJoint Industry Council c/o AMT - The Association for Manufacturing Engineering
  • 7901 Westpark Dr., McLean, VA 22101
Electronic Industries Alliance
www.eia.org
EIAElectronic Industries Alliance
  • 2500 Wilson Blvd. # 310, Arlington, VA 22201-3834




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