UL 711 CRD-2016 UL Standard for Safety Rating and Fire Testing of Fire Extinguishers - Section Paragraph Reference 9 Subject Class C extinguishers (Edition 7 December 17 2004).pdf

1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared by UL LLC. It is normative for the applicable ULProduct Certification Program(

2、s); however, it is currently not part of the UL Standard(s) referencedbelow.Product Category (CCN): FXHV, GAOM, GBAR, GMBY, GNVY, GOYZ, GOZZ, GPAZ,GPBG, GPCZ, GPEZ, GPFH, GPGZ, GPIAStandard Number: UL 711Standard Title: Standard for Rating and Fire Testing of Fire ExtinguishersEdition Date: December

3、 17, 2004Edition Number: 7Section / Paragraph Reference: 9Subject: Class C extinguishersDECISION:9 Class C extinguishers9.1 General9.1.1 The discharge of an agent from an extinguisher charged with its rated capacity, when tested asspecified in the Clause 9.2, Electrical Conductivity Test, shalla) no

4、t show a visible breakdown between the electrically charged target and the dischargingextinguisher; andb) shall not increase the electrical conductivity of the extinguisher more than 1.0 milliampere asmeasured by a milliammeter.9.1.2 The Class C designation is to be provided for an extinguisher only

5、 in conjunction with a ratingpreviously established under the requirements for Class A, Class B, Class D, Class K, or any combination.9.1.3 No tests for the fire-extinguishing ability of a Class C extinguisher on electrical fires are to beconducted. There are to be, therefore, no numerical component

6、s for Class C ratings as only thenonconducting characteristics of the agent as discharged are significant.9.1.4 The test method for electrical conductivity of the discharge is:a) To impress a high-voltage of 100,000 VAC 60 hertz, alternating current between anelectrically insulated extinguisher and

7、an electrically charged target; andb) To measure the current flow, when any, through the path formed by the agent during theperiod it is being discharged towards the target.9.2 Electrical conductivity test9.2.1 The mounting for the extinguisher is to consist of an insulating platform made of four sh

8、eets of glassor polymethylmethacrylate (PMMA) Plexiglas measuring approximately at least 710 610 by 760 610 by 13mm (28 24 by 30 24 by 1/2 in), each layer separated by three 50-mm (2-in) ceresin (wax) or PMMAPlexiglas blocks measuring at least 50-mm (2-in) in height and at least 35-mm (1-3/8-in) in

9、diameter. SeeFigure 4. The bottom plate is to rest directly on a platform having limited conductivity, such asof drylumber.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL9.2.2 The extinguisher is to be supported in a wooden framework or scaff

10、old manufactured from materialhaving limited conductivity (such as lumber) by two well-shellacked dry wooden cross bars having limitedconductivity (such as phenolic composition) and the extinguisher, bolted to clamp the cylinder clamped tothe cross bars. The ends of these cross bars are to rest inbe

11、 electrically insulated bearings when securedto the scaffold leg braces. Plates and blocks of material having limited conductivity (such as phenoliccomposition) are to furnish be used, if necessary, to provide additional electrical insulation between theextinguisher and the clamp and scaffold member

12、s. The top of the scaffold is to be sufficiently mounted,1.5 m (5 ft) above the floor ona,istobewood planked to form a 1.2 by 1.2 m (4 by 4 ft) working platform,typically 1.2 by 1.2 m (4 by 4 ft) in size, if provided.9.2.3 Operation of the extinguisher valve is to be provided by an extension rod hav

13、ing limited conductivity(such as of phenolic composition) or other insulated means of remote control providing for safe handling.9.2.4 A target of sheet copper, 300 by 300 mm by 3 mm (12 by 12 in by 1/8 in), is to be constructed forreceiving the discharge from the extinguisher. See Figure 4. The she

14、et is to be bent at 90 degrees (1.57rads), to an outside radius of 12.7 mm (1/2 in), forming a V, each side of which measures 300 by 150 mm(12 by 6 in). The target is to be buffed to remove all sharp edges or burrs. The target is to be supportedon a metal (such as copper) stem of diameter 19 mm (3/4

15、 in) soldered welded to the inside of the targetat the apex. The lower end of this the stem is to be secured to a pedestal of phenolic compositionapproximately 50 mm (2 in) thick. The pedestal is to be supported on an insulating platform consisting offour glass or PMMA plates measuring at least 300

16、by 300 by 13 mm (12 by 12 by 1/2 in) glass or Plexiglasplates separated from each other by three ceresin or PMMA blocks measuring at least 50 mm (2 in) inheight and at least 35 mm (1-3/8 in) in diameter between each plate 50 by 50 by 13 mm (2 by 2 by 1/2in) ceresin or Plexiglas blocks between each p

17、late. The bottom plate is to rest on an electrically insulatedstand, such as a dry wood lumber stand. The target assembly or extinguisher assembly is to be adjustedfor height to center the target plate opposite the open end of the extinguisher horn or discharge nozzle.9.2.5 The extinguisher horn han

18、dle or nozzle handle in all tests is to be wrapped with metal (such asaluminum) foil which, in turn, is to make electrical contact with a bare copper wirethe extinguisher valve.The A bare No. 8 AWG copper wire is to be No. 8 AWG and strapped on the outside of the horn or nozzle.and The copper wire i

19、s to run from the foil to the discharge end of the extinguisher and , being bent at aright angles across the mouth of the horn or nozzle to carry current to the point of discharge. The otherend of the copper wire extinguisher is to be connected to the high side of the transformer (that is, theungrou

20、nded side of the circuit)as shown in Figure 5. The target, with its metallic supports, is to beconnected to the grounded side of the test circuit.Exception: When the copper wire can potentially interfere with the discharging agent, the copper wire shallbe installed such that it is only in contact wi

21、th the foil that is in contact with the discharging agent.9.2.6 The voltage source shall provide a 100,000 VAC potential to the target to be employed throughoutthe tests is to be derived from a transformer rated at 60 hertz, 5 kilovolt-ampere capacity, 125 to 100,000volts, or the equivalent. The tra

22、nsformer primary circuit is to be energized from a 60 hertz line through aninduction regulator which is to provide a continuously variable secondary voltage from 0 to 100,000 volts.The secondary potentials are to be measured through a potential transformer contained within the testtransformer having

23、 ratios of 1 to 250 volts and 1 to 500 volts, respectively, in conjunction with a suitablevoltmeter. A 125 mm sphere gap is to be connected across the secondary of the test transformer forprotective purposes, the gap is to be opened such that the arc over does not occur at the potential beingemploye

24、d in the test. One leg of the test circuit is to be grounded at the sphere gap. See schematicdiagram of wiring, Figure 5.9.2.7 A thermocouple milliammeter calibrated to an accuracy of 0.5 percent, with thermocouple elementsof 10, 3, and 1.5 milliamperes, is to be employed to measure the current flow

25、 between the extinguisherand the target. In using a meter of this type, the readings are apt to be influenced by radio frequency (RF)STANDARD NUMBER: UL 711 -2-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULcurrents. Therefore, in the assembl

26、y of the apparatus, a capacitor rated 0.005 microfarads is to beconnected across the meter terminals to shunt out these RF currents. The meter is to be installed in twobox-like enclosures made of copper screen wire separated from each other by insulators. The outerscreen enclosure is to be connected

27、 to the shield of the meter leads and to ground. The meter is to beconnected in the grounded leg of the transformer at all times.9.2.78 The reading indicating passage of current across the gap between the extinguisher and the targetwhen no extinguishing agent is being discharged is to be called the

28、meter-tare.9.2.9 When thermocouple units are used in the tests, the current flow through the capacitor is to becalculated on the basis of a 60 hertz current. Since the 1.5 mA thermocouple unit requires approximately1240 millivolts drop across the meter terminals to produce full-scale deflection, the

29、 current flow throughthe capacitor is to be calculated on the basis of this unit. The value of current shunted around the meterthrough the capacitor is negligible as compared with the current flow recorded by the meter.9.2.10 8 The extinguisher is to be placed secured within the scaffold on the insu

30、lated platform andconnected to the high side of the transformer (that is, the ungrounded side of the circuit). When more thanone type of horn or nozzle is used on the extinguisher under test, the test is to be conducted using eachtype.9.2.11 9 Each horn or nozzle is to be equipped with a No. 8 AWG w

31、ire. The target is to be placed atvarying distances of 250 mm (10 in) and greater from the open end of the horn or nozzle to determine theminimum distance at which a potential of 100,000 volts VAC is capable of complying with 9.1.1beingmaintained without a flash over. The extinguisher is to be opera

32、ted for 202 seconds, discharging theagent against the target with a potential of 100,000 volts VAC impressed between the extinguisher andtarget, without visible effects. The condition is to be checked for at least an additional 15 secondsdischarge.Exception: For extinguishers that cannot accommodate

33、 the 20 second and 15 second dischargedurations, the initial discharge is to be 60 5 percent of the specified total discharge duration and theadditional discharge duration is to be the remainder of the specified total discharge duration.9.2.12 10 The test is to be repeated, using each type horn or n

34、ozzle when more than one type of horn ornozzle is used on the extinguisher under test. or other modification and The test is also to be repeated isto be conducted at least once with the target plate heated to an initial temperature of 370C (700F) priorto the discharge of the extinguisher.Note: An ac

35、ceptable means to heat the target plate is to heat the back side of the target with a propanetorch that has a wide flame distribution pattern. The temperature can be measured with a thermocoupleplaced in a hole of the stem attached to the target. The hole is to be parallel to the axis of the stem,ce

36、ntrally located, and 140 mm (5-1/2 in) deep as measured from the top of the stem. A number 40 drill bit2.489 mm (0.098 in) has been found to be suitable for the hole to accommodate the thermocouple. Theresponse time characteristics of the thermocouple chosen are to be considered for suitability in t

37、hisapplication. A sheathed, Type K thermocouple is recommended.This is generated text for figtxt.STANDARD NUMBER: UL 711 -3-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULFigure 4Extinguisher and targetNote: Figure shows insulating supports a

38、nd wire on horn.Figure 5Test diagramNote: Figure is a test diagram showing electrical connections and circuits.STANDARD NUMBER: UL 711 -4-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULFigure 4Extinguisher and target configuration example1 ex

39、tinguisher;2 insulating platform;3 scaffold and working platform;4 cross bars;5 extension rod;6 pulley clamped to extinguisher;7 target;8 pedestal support bar;9 target stand;10 extinguisher horn or discharge nozzle;11 copper wireSTANDARD NUMBER: UL 711 -5-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR F

40、URTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULRATIONALE FOR DECISION:The Class C extinguisher test was reviewed and found not to be current when considering availablematerials and operating procedures. These revisions remove restrictive descriptions that are notnecessary, or are no lo

41、nger available, and clarify current operating procedures when considering availabletechnology. As submitted, these changes will not necessitate reevaluation of presently listed products. The insulating platform dimensions have been clarified as a minimum and the materials ofconstruction clarified to

42、 coincide with current operating procedures. The scaffold material has been clarified to coincide with current operating procedures. The working platform and insulating platform materials and dimensions have been clarified tocoincide with current operating procedures. The insulating platform for the

43、 extinguisher has been decreased in size to consider readilyavailable materials. The blocks have been increased in diameter to provide greater stability. The thickness of the copper target has been clarified to coincide with current operatingprocedures. The material and diameter of the stem attached

44、 to the target, as well as, the method ofattachment of the stem and target have been clarified to coincide with current operatingprocedures. The recommended foil material intended to be wrapped on the extinguisher has been clarifiedto coincide with current operating procedures. Obsolete equipment re

45、ferences have been removed and the voltage source potentialspecified. An exception has been added to consider extinguishers that have a total discharge time lessthan 35 seconds. A note containing the recommended method to heat the plate and measure the temperaturehas been added.Copyright 2016 UL LLC

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49、 outdated.STANDARD NUMBER: UL 711 -6-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULThis document is published as a service to ULs certification customersSTANDARD NUMBER: UL 711 -7-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULSTANDARD NUMBER: UL 711 -8-No Text on This Page