1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULJune 20, 20061SUBJECT 1652OUTLINE OF INVESTIGATIONFORFLEXIBLE METALLIC TUBINGIssue Number: 3JUNE 20, 2006Summary of TopicsThis is the Third Issue of Subject 1652, Outline of Investigation forFlex
2、ible Metallic Tubing, covering flexible metallic tubing designed for useas metal raceway for wires and cables. A revision to the product markingin paragraph 18.2.1 has been included.The UL Foreword is no longer located within the UL Standard. For informationconcerning the use and application of the
3、requirements contained in thisStandard, the current version of the UL Foreword is located onULStandardsInfoNet at: http:/ 2006 UNDERWRITERS LABORATORIES INC.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULJUNE 20, 2006SUBJECT 16522No Text on T
4、his PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULCONTENTSINTRODUCTION1 Scope .42 General 42.1 Units of Measurement .4CONSTRUCTION3 Strip Material .44 Thickness of Strip .45 Splices 56 Interior Surfaces 57 Tubing Diameters .5PERFORMANCE8
5、 Zinc Coating Test .69 Tension Test .710 Flexibility In-Use Test 911 Impact Test 1112 Resistance and Secureness of Tubing in Fittings .1213 Resistance Test 1214 Crushing Test 1215 Fixed Bend Test 1316 Tube Tightness Test 1317 Fault-Current Test 14MARKINGS18 Details .1418.1 Manufacturer 1418.2 Tag .1
6、5JUNE 20, 2006 SUBJECT 1652 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULINTRODUCTION1 Scope1.1 These requirements cover flexible metallic tubing designed for use as metal raceway for wires andcables in accordance with the National Electri
7、cal Code, NFPA 70.2 General2.1 Units of Measurement2.1.1 Values stated without parentheses are the requirement. Values in parentheses are explanatory orapproximate information.CONSTRUCTION3 Strip Material3.1 The strip material used in flexible metallic tubing shall be of carbon steel, shall have a t
8、ensile strengthof at least 34,000 lbf/in2(234.4 MPa) and shall be of uniform width and thickness throughout. All surfacesof the strip shall be free from scale and rust before application of the protective zinc coating covered inthe Zinc Coating Test, Section 8.3.2 Compliance of tubing with the surfa
9、ce-cleanliness requirement in 3.1 is to be determined by visualinspection.4 Thickness of Strip4.1 The thickness of the metal strip used for flexible metallic tubing shall not be less than indicated inTable 4.1 for the specified tubing type.Table 4.1Strip thicknessMinimum acceptable thickness of stri
10、pTrade size of tubing (Metric Designator) Inch (mm)3/8 12 0.009 0.231/2 16 0.009 0.233/4 21 0.009 0.234.2 Compliance of tubing with the requirement in 4.1 is to be determined by measuring the strip beforeforming with a flat-nose machinists micrometer caliper calibrated to read directly to at least 0
11、.001 inch(0.01 mm). The thickness of a particular strip is to be determined as the average of five measurements.JUNE 20, 2006SUBJECT 16524UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL5 Splices5.1 Splices in a steel strip shall be made in a
12、workmanlike manner and shall not materially increase thethickness or diameter of the tubing or lessen its mechanical strength.5.2 Compliance of tubing with the requirement in 5.1 is to be determined by visual inspection.6 Interior Surfaces6.1 The interior surfaces of finished metallic tubing shall b
13、e free from burrs and sharp edges that candamage wiring.6.2 Compliance of tubing with the requirement in 6.1 is to be determined by visual examination of theinterior surfaces. A specimen of tubing approximately 1 ft (300 mm) in length is to be inspected by lookingthrough it (first from one end then
14、from the other) at an artificial light.7 Tubing Diameters7.1 Finished flexible metallic tubing shall have dimensions indicated in Table 7.1 (dimensions in inches)or Table 7.2 (dimensions in millimeters).Table 7.1Internal and external diameters in inchesTrade size oftubing(Metricdesignator)Acceptable
15、 external diameters Acceptable internal diametersMinimum Maximum Minimum Maximum3/8 12 0.560 0.664 0.484 0.5041/2 16 0.740 0.800 0.620 0.6403/4 21 0.940 1.000 0.820 0.840Table 7.2Internal and external diameters in millimetersTrade size oftubingMetric designator Acceptable external diameters Acceptab
16、le internal diametersMinimum Maximum Minimum Maximum3/8 12 14.22 15.49 9.52 9.961/2 16 18.80 20.32 15.75 16.263/4 21 23.88 25.40 20.83 21.347.2 Compliance of the tubing with the minimum and maximum dimensions in Table 7.1 or 7.2 is to bedetermined by means of a vernier caliper or its equivalent.JUNE
17、 20, 2006 SUBJECT 1652 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULPERFORMANCE8 Zinc Coating Test8.1 The coating of zinc on flexible metallic tubing shall be such that all of the following requirements aremet:a) A specimen of the zinc-coa
18、ted strip tested before forming shall not show a bright, adherentdeposit of copper on any surface, including edges, after one 60-second immersion in a solutionof copper sulphate.b) A specimen of partially uncoiled tubing from finished tubing shall not show a bright, adherentdeposit of copper after o
19、ne 60-second immersion in a solution of copper sulphate.8.2 The solution of copper sulphate is to be made from distilled water and the American Chemical Society(ACS) reagent grade of cupric sulphate (CuSO4). In a copper container or in a glass, polyethylene, orother chemically nonreactive container
20、in which a bright piece of copper is present, a quantity of the cupricsulphate is to be dissolved in hot distilled water to obtain a solution that has a specific gravity slightlyhigher than 1.186 after the solution is cooled to a temperature of 18.3C (65.0F). Any free acid that mightbe present is to
21、 be neutralized by the addition of approximately 1 gram of cupric oxide (CuO) or 1 gramof cupric hydroxide Cu(OH)2 per liter of solution. The solution is to be diluted with distilled water to obtaina specific gravity of exactly 1.186 at a temperature of 18.3C (65.0F). The solution is then to be filt
22、ered.8.3 At one end of a sample length of flexible metallic tubing, the tubing is to be unwound from the outsideto expose to view both edges and the inner surface of the formed strip, and to facilitate workingcheesecloth between the turns onto the inner surface to dry that surface during the test. T
23、o reduce thedamage to the zinc coating, the strip is not to be straightened as it is unwound but is to remain in thehelical form with a diameter no larger than three times the tubing diameter. Three 6-inch (150-mm) (axialmeasurement) specimens are to be cut from the partially uncoiled tubing. Additi
24、onally, three straight6-inch (150-mm) specimens are to be cut from a sample length of the zinc-coated steel before forming.8.4 With prudent attention to the risks to health and to the risk of fire involved, the six specimens are tobe cleaned with an organic solvent. Each specimen is to be examined f
25、or evidence of damage to the zinccoating during specimen preparation (not during forming). Only specimens that are not damaged are tobe selected for use in the test. One specimen of the unformed strip and one specimen of the tubing areto be tested.8.5 The two selected specimens are to be rinsed in w
26、ater, and all of its surfaces are to be dried with cleancheesecloth. As much of the water as possible is to be removed in the drying operation, because waterslows the reaction between the zinc and the solution and adversely affects the test results. The surfaceof the zinc is to be dry and clean befo
27、re a specimen is immersed in the copper sulphate solution. Thespecimens are not to be touched by hands or anything else that can contaminate or damage the surfaces.8.6 A glass, polyethylene, or other chemically nonreactive beaker having a diameter equal to twice thediameter measured over the specime
28、n of partially uncoiled tubing is to be filled with the solution of coppersulphate to a depth of not less than 3 inches (76 mm). The temperature of the solution is to be maintainedat 18.3 1.1C (65.0 2.0F).JUNE 20, 2006SUBJECT 16526UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDIS
29、TRIBUTION WITHOUT PERMISSION FROM UL8.7 One of the selected specimens is to be immersed in the solution and supported on end in the centerof the beaker so that not less than half of its axial length is immersed. The specimen is to remain in thesolution for 60 seconds, during which time it is not to
30、be moved; nor is the solution to be stirred.8.8 At the end of the 60-second period the specimen is to be:a) Removed from the beaker,b) Rinsed immediately in running tap water,c) Rubbed with clean cheesecloth (a clean soft-bristle test-tube or bottle brush in goodcondition and of applicable size may
31、be used to rub the interior surfaces of the specimen ofpartially uncoiled tubing, but cheesecloth is to be used on the other surfaces of this specimenand on the unformed strip) until any loosely adhering deposits of copper are removed,d) Dried with clean cheesecloth.The turns of the specimens of par
32、tially uncoiled tubing are not to be further separated during this process.Again, hands and other damaging and contaminating objects and substances are not to touch thesurfaces that were immersed. The part of the specimen that was immersed is to be examined, consideringeach edge and broad surface se
33、parately and disregarding the portion of the specimen within 1/2 inch (13mm) of its immersed end.8.9 If the part of the specimen that was immersed has any deposit of bright, firmly adhering copperoutside the 1/2-inch (13-mm) end portion, an estimate of the percentage of each edge and broad surfaceth
34、at is covered with copper is to be made and recorded.8.10 Neither the tubing nor the unformed metal strip is acceptable if there is any bright adherent coppershowing outside the 1/2-inch (13-mm) end portion of the immersed part of the unformed strip specimenafter the dip. Even if the unformed strip
35、is acceptable, the tubing is not acceptable if the specimen ofpartially uncoiled tubing shows bright adherent copper after the dip.9 Tension Test9.1 Finished flexible metallic tubing shall withstand for 1 minute, without opening at any point, a tensionimparted by a weight that exerts 150 lbf (667 N
36、or 68 kgf) applied to the ends of a 44-inch (1115-mm)length of tubing.9.2 The apparatus is to consist of a pair of clamps, a weight as indicated in 9.1, and a means forsuspending the weight from a support.9.3 The clamps are to be made of hardwood. The two pieces comprising each clamp are to be faste
37、nedtogether by two bolts so that the tubing can be clamped tightly between the jaws without crushing. Theweights are to be equipped with a means for attachment to the clamps. A method such as a block andtackle may be used to lift the sample, clamps, and weight (see Figure 9.1).This is generated text
38、 for figtxt.JUNE 20, 2006 SUBJECT 1652 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULFigure 9.1Tension testJUNE 20, 2006SUBJECT 16528UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL9.
39、4 A 44-inch (1115-mm) specimen of tubing is to be clamped so that its ends project 2 inches (50 mm)beyond the edges of each clamp, thus providing a specimen 36 inches (915 mm) long between theclamps, which are then to be tightened only as much as is necessary to keep the specimen from slipping.9.5 W
40、hen a differential pulley or a block and tackle is used, the specimen is to be suspended by the upperclamp with a loop of rope passing over the hook of the pulley or block and tackle hung from a support. Aweight as indicated in 9.1 is to be attached to the lower clamp. The specimen is to hang vertic
41、ally for itsfull length and at right angles to the face of the clamps. The specimen, clamps, and weight are then to beraised gradually so that tension is applied to the specimen at a rate not to exceed 100 lbf/min (444 N/minor 45 kgf/min) until the weight just clears the floor and hangs freely in ai
42、r. The weight is to be kept by handfrom rotating. The weight is to be supported by the specimen for 1 minute and then lowered to the floorand the weight and clamps removed. The tubing is to be observed to determine whether the edges ofadjacent convolutions are separated to expose its interior.10 Fle
43、xibility In-Use Test10.1 A total of five samples of flexible metallic tubing in each trade size are to be subjected to the testspecified in 10.2. The tubing shall show no opening, cracks or separations of the convolutions aftercompletion of 100 cycles of flexing.10.2 A 4-1/2 ft (137-cm) length of th
44、e tubing is to have one end secured to a fitting, intended for use withthe tubing, and placed in a fixed vertical upright position. The tubing is to be bent into a U-shape so thatthe unrestrained end of the tube is hanging vertically over the edge of a semi-circular shaped form. Theform is to have a
45、 diameter indicated in Table 10.1. See Figure 10.1. The form edge is to be provided witha length of 3/4-inch (20-mm) electrical metallic tubing to provide a smooth surface for the tubing to rubagainst during flexing. The unrestrained end of the tube is to be manually moved up and down from apoint wh
46、ere the tube is in full contact with the form to where the unrestrained end is level with the fitting.The up and down motion is to be at a rate of 5 cycles per minute. The test sample is to be in rubbingcontact with the electrical metallic tubing surface, with the unrestrained end at its lowest posi
47、tion.Table 10.1Diameter of test formDiameter of test surfaceTrade size of tubing (Metric Designator) Inches (mm)3/8 12 20.0 5101/2 16 25.0 6353/4 21 35.0 890This is generated text for figtxt.JUNE 20, 2006 SUBJECT 1652 9UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WI
48、THOUT PERMISSION FROM ULFigure 10.1Flexibility in use testJUNE 20, 2006SUBJECT 165210UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL11 Impact Test11.1 The impact strength of finished flexible metallic tubing is to be determined as described i
49、n 11.2 11.4. Deformation of the tubing shall be less than 50 percent when measuring the overall diameter of thetubing after impact and comparing it to the original value.11.2 Five specimens of the finished tubing 15 inches (380 mm) long are to be subjected to the impactforce indicated in Table 11.1 by means of a freely falling weight.Table 11.1Impact forceForceTrade size of tubing (Metric Designator) ft-lbf (N)3/8 12 25 1101/2 16 25 1103/4 21 30 13511.3 A solid steel block measuring 3 by 4 by 6 inches (76 by 102 by 152
