NEMA Types – Definitions Pertaining to Nonhazardous Locations
Enclosures for Electrical Equipment
An enclosure is a surrounding case constructed to provide protection from accidental contact with the enclosed equipment and to provide protection to the enclosed equipment from specified environmental conditions. A brief description of the more common types of enclosures used by the electrical industry follows.
Type 1 Enclosure: Intended for indoor use primarily to provide protection against contact with enclosed equipment.
Type 2 Enclosure: Intended for indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt.
Type 3 Enclosure: Intended for outdoor use primarily to provide a degree of protection against wind-blown dust, rain, sleet and external ice formation.
Type 3R Enclosure: Intended for outdoor use primarily to provide a degree of protection against falling rain, sleet and external ice formation.
Type 3S Enclosure: Intended for outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet, and to provide for operation of external mechanism when ice laden.
Type 3X Enclosure: Intended for outdoor use primarily to provide a degree of protection against corrosion, wind-blown dust, rain, sleet and external ice formation.
Type 3SX Enclosure: Intended for outdoor use primarily to provide a degree of protection against corrosion, wind-blown dust, rain, and sleet, and to provide for operation of external mechanism when ice laden.
Type 4 Enclosure: Intended for indoor or outdoor use primarily to provide a degree of protection against wind-blown dust and rain, splashing water and hose-directed water.
Type 4X Enclosure: Intended for indoor or outdoor use primarily to provide a degree of protection against corrosion, wind-blown dust and rain, splashing water and hose-directed water.
Type 6 Enclosure: Intended for indoor or outdoor use primarily to avoid a degree of protection against contact with enclosed equipment, falling dirt, hose-directed water, entry of water during occasional temporary submersion at a limited depth and external ice formation.
Type 6P Enclosure: Intended for indoor or outdoor use primarily to provide a degree of protection against contact with enclosed equipment, falling dirt, hose-directed water, entry of water during prolonged submersion at a limited depth and external ice formation.
Type 12 Enclosure: Intended for indoor use primarily to provide a degree of protection against dust, falling dirt and dripping noncorrosive liquids.
Type 13 Enclosure: Intended for indoor use primarily to provide a degree of protection against dust, spraying of water, oil and noncorrosive coolant.
IP (Ingress Protection) Rating for Equipment and Enclosures
A two-digit number (as specified in Australian Standards AS60529 and EN60529) is used to provide an IP Rating to a piece of electronic equipment or to an enclosure for electronic equipment.
The two digits represent three different forms of environmental influence:
The first digit represents protection against ingress of solid objects
The second digit represents protection against ingress of liquids
The larger the value of each digit, the greater the protection from that influence. As an example, a product rated as IP57 would be better protected against environmental factors than another similar product that was only rated as IP43. Our Gel Connectors are rated at IP67 (totally protected against dust ingress and withstands immersion up to a depth of 1 metre).
Value First Digit Second Digit
Protection against ingress Protection against ingress
of solids of liquids
0 No protection No protection
1 Protected against solid Protected against vertically
objects over 50mm e.g. falling drops of water.
hands, large tools
2 Protected against solid objects over Protected against direct sprays of water up to 15°
12mm e.g. hands, large tools from vertical.
3 Protected against solid objects over Protected against direct sprays of water up to 60°
2.5mm e.g. wire, small tools from vertical.
4 Protected against solid objects over Protected against water sprayed from any direction.
1.0mm e.g. wires Limited ingress permitted.
5 Limited protection against dust ingress Protected against low pressure water jets from any
(no harmful deposit) direction. Limited ingress permitted.
6 Totally protected against dust ingress. Protected against high pressure water jets from any
direction. Limited ingress permitted.
7 - Protected against immersion between 15cm and 1M.
8 - Protected against long periods of immersion under pressure.
9 - -
2011年1月17日 星期一
Inconel(From Wikipedia)
Inconel is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.[1] Inconel alloys are typically used in high temperature applications. It is often referred to in English as "Inco" (or occasionally "Iconel"). Common trade names for Inconel include: Inconel 625, Chronin 625, Altemp 625, Haynes 625, Nickelvac 625 and Nicrofer 6020.[2]
Composition
Different Inconels have widely varying compositions, but all are predominantly nickel, with chromium as the second element.
Properties
Inconel alloys are oxidation and corrosion resistant materials well suited for service in extreme environments. When heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high temperature applications where aluminum and steel would succumb to creep as a result of thermally-induced crystal vacancies (see Arrhenius equation). Inconel's high temperature strength is developed by solid solution strengthening or precipitation strengthening, depending on the alloy. In age hardening or precipitation strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni3Nb or gamma prime (γ'). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.
Machining
Inconel is a difficult metal to shape and machine using traditional techniques due to rapid work hardening. After the first machining pass, work hardening tends to plastically deform either the workpiece or the tool on subsequent passes. For this reason, age-hardened Inconels such as 718 are machined using an aggressive but slow cut with a hard tool, minimizing the number of passes required. Alternatively, the majority of the machining can be performed with the workpiece in a solutionised form, with only the final steps being performed after age-hardening. External threads are machined using a lathe to "single point" the threads, or by rolling the threads using a screw machine. Holes with internal threads are made by welding or brazing threaded inserts made of stainless steel. Cutting of plate is often done with a waterjet cutter. Internal threads can also be cut by single point method on lathe, or by threadmilling on a machining center. New whisker reinforced ceramic cutters are also used to machine nickel alloys. They remove material at a rate typically 8 times faster than carbide cutters. 718 Inconel can also be roll threaded after full aging by using induction heat to 1300 degrees F without increasing grain size.[citation needed]
Joining
Welding inconel alloys is difficult due to cracking and microstructural segregation of alloying elements in the heat affected zone. However, several alloys have been designed to overcome these problems. The most common welding method is gas tungsten arc welding.[7]
New innovations in pulsed micro laser welding have also become more popular in recent years.
Uses
Inconel is often encountered in extreme environments. It is common in gas turbine blades, seals, and combustors, as well as turbocharger rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and pressure vessels, heat exchanger tubing, steam generators in nuclear pressurized water reactors, natural gas processing with contaminants such as H2S and CO2, firearm sound suppressor blast baffles, and Formula One and NASCAR exhaust systems.[8][9] Inconel is increasingly used in the boilers of waste incinerators.[10] The Joint European Torus vessel is made in Inconel.[11] Inside JET a plasma is heated to temperatures that are higher than those found in the Sun. A strong magnetic field keeps the plasma away from the vessel.
North American Aviation constructed the skin of the X-15 rocket plane out of an Inconel alloy known as "Inconel X".[12]
Rolled Inconel was frequently used as the recording medium by engraving in Black Box recorders on aircraft[13]
Alternatives to the use of Inconel in chemical applications like scrubber, columns, reactors, and pipes is Hastelloy, perfluoroalkoxy (PFA) lined carbon steel or fiber reinforced plastic.
Inconel alloys
Inconel 600: Solid solution strengthened
Inconel 625: Acid resistant, good weldability
Inconel 690: Low cobalt content for nuclear applications, and low resistivity[14]
Inconel 718: Gamma double prime strengthened with good weldability
Inconel 751: Increased aluminum content for improved rupture strength in the 1600°F range[15]
Inconel 939: Gamma prime strengthened with good weldability
Composition
Different Inconels have widely varying compositions, but all are predominantly nickel, with chromium as the second element.
Properties
Inconel alloys are oxidation and corrosion resistant materials well suited for service in extreme environments. When heated, Inconel forms a thick, stable, passivating oxide layer protecting the surface from further attack. Inconel retains strength over a wide temperature range, attractive for high temperature applications where aluminum and steel would succumb to creep as a result of thermally-induced crystal vacancies (see Arrhenius equation). Inconel's high temperature strength is developed by solid solution strengthening or precipitation strengthening, depending on the alloy. In age hardening or precipitation strengthening varieties, small amounts of niobium combine with nickel to form the intermetallic compound Ni3Nb or gamma prime (γ'). Gamma prime forms small cubic crystals that inhibit slip and creep effectively at elevated temperatures.
Machining
Inconel is a difficult metal to shape and machine using traditional techniques due to rapid work hardening. After the first machining pass, work hardening tends to plastically deform either the workpiece or the tool on subsequent passes. For this reason, age-hardened Inconels such as 718 are machined using an aggressive but slow cut with a hard tool, minimizing the number of passes required. Alternatively, the majority of the machining can be performed with the workpiece in a solutionised form, with only the final steps being performed after age-hardening. External threads are machined using a lathe to "single point" the threads, or by rolling the threads using a screw machine. Holes with internal threads are made by welding or brazing threaded inserts made of stainless steel. Cutting of plate is often done with a waterjet cutter. Internal threads can also be cut by single point method on lathe, or by threadmilling on a machining center. New whisker reinforced ceramic cutters are also used to machine nickel alloys. They remove material at a rate typically 8 times faster than carbide cutters. 718 Inconel can also be roll threaded after full aging by using induction heat to 1300 degrees F without increasing grain size.[citation needed]
Joining
Welding inconel alloys is difficult due to cracking and microstructural segregation of alloying elements in the heat affected zone. However, several alloys have been designed to overcome these problems. The most common welding method is gas tungsten arc welding.[7]
New innovations in pulsed micro laser welding have also become more popular in recent years.
Uses
Inconel is often encountered in extreme environments. It is common in gas turbine blades, seals, and combustors, as well as turbocharger rotors and seals, electric submersible well pump motor shafts, high temperature fasteners, chemical processing and pressure vessels, heat exchanger tubing, steam generators in nuclear pressurized water reactors, natural gas processing with contaminants such as H2S and CO2, firearm sound suppressor blast baffles, and Formula One and NASCAR exhaust systems.[8][9] Inconel is increasingly used in the boilers of waste incinerators.[10] The Joint European Torus vessel is made in Inconel.[11] Inside JET a plasma is heated to temperatures that are higher than those found in the Sun. A strong magnetic field keeps the plasma away from the vessel.
North American Aviation constructed the skin of the X-15 rocket plane out of an Inconel alloy known as "Inconel X".[12]
Rolled Inconel was frequently used as the recording medium by engraving in Black Box recorders on aircraft[13]
Alternatives to the use of Inconel in chemical applications like scrubber, columns, reactors, and pipes is Hastelloy, perfluoroalkoxy (PFA) lined carbon steel or fiber reinforced plastic.
Inconel alloys
Inconel 600: Solid solution strengthened
Inconel 625: Acid resistant, good weldability
Inconel 690: Low cobalt content for nuclear applications, and low resistivity[14]
Inconel 718: Gamma double prime strengthened with good weldability
Inconel 751: Increased aluminum content for improved rupture strength in the 1600°F range[15]
Inconel 939: Gamma prime strengthened with good weldability
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