Research determines performance of high-volume fog nozzles

Research determines performance of high-volume fog nozzles


MODERN FACILITIES plus a cooperative administration and topnotch technical personnel has resulted in Rochester being the scene of several fire service research projects in the past few years. Most recent were the large-capacity fog nozzle tests held in September of 1959 by the Subcommittee on Heavy Stream Devices, Committee on Fire Department Equipment, NFPA and I.A.F.C.

The purpose of the tests was to evaluate in a standard manner the performance of the various large-volume fog nozzles which have appeared on the market in the past few years. The information derived could then be promulgated to the fire service in order that fire chiefs would have accurate data upon which to base fire fighting operations involving the equipment. The information reported will also be of great assistance to pump operators who must supply the lines employing these nozzles.

Measuring the flow in large-capacity fog nozzles at the various pressures and settings was a difficult problem until recently. Deputy Chief Louis Vogt of Rochester worked with the Taylor Instrument Co. of that city to develop differential pressure rate of flow meters which greatly simplified the test procedures. These instruments were employed by the subcommittee during the tests and proved very satisfactory for the purpose.

Subcommittee chairman, Chief Vogt looks on as Taylor engineer, Ray Owen, checks recorder on test standElkhart JK-2500 discharging 2,050 gpm at 30 degrees. High-volume nozzle exceeded range of equipment


Note 1:—Where no maximum angle reading is given it indicates wide or 90 degree pattern is maximum.

Note 2:— no settings were provided by manufacturer figures in brackets indicate committee settings.

Note 3:—In case where flows exceed 2000 gpm results were calculated on the basis of flows at highest pressures which could be accurately measured.

Note 4:—Variations in straight stream flows in some nozzles are due to difficulty in determining “best” stream. Reading were taken at several settings to provide range of discharge possible. Note 5:—Powhatan did not make heavy stream nozzles at time of test but supplied largest hand line nozzle offered by the company.

According to Taylor engineers, the differential flow meters have an accuracy of approximately ±2 per cent, well within accepted fire service requirements. This was verified by the committee by testing straight stream nozzle tips. The results agreed closely with published fire stream tables for such tips.

Santa Rosa A-6 nozzle set at maximum angle. Water curtain effect estimated to be nearly 180 degreesWooster 500 nozzle at 90-degree pattern set by committee. Measurement of photo angle was 80 degrees

The subcommittee tested 17 different commercially available nozzles which were rated at 500 gpm or over with one exception. All were tested at 100-psi nozzle pressure measured at the base of the nozzle again with one exception: a 2,500-gpm nozzle which had to be tested at a lower pressure in order to keep the flow under the 2,000-gpm limit of the recording devices. All discharge data were automatically recorded on a Taylor Instrument Co. meter chart for permanent record.

Actual flows in gpm were determined at the various pattern settings of the adjustable nozzles as stated by the manufacturers. The subcommittee agreed on a uniform method of measuring the angle of pattern in order to standardize the tests since the manufacturers’ settings varied in degree. Photographs of the committee settings were taken and later during the data correlation, the actual angle of setting was measured with a protractor and recorded in the report. It was felt by the subcommittee that standards of measuring and setting pattern angles should be established to promote uniformity among the manufacturers.

The judgment of the subcommittee was also employed as the factor for determining a straight stream for an adjustable nozzle. In addition, all adjustable nozzles were tested at the wide-open or maximum-pattern setting if this was greater than 90 degrees.

The subcommittee has recommended that further studies be conducted of these nozzles where employed on ladder pipes. In this manner the nozzle reaction at the various pressures and flows can be evaluated and promulgated to the fire service.

Rockwood Type B 500-gpm nozzle photographed when pressure was 90 psi. Measurement of photos when discharging at 100 psi indicates set pattern angle of 70 degreesAkron Fog Hog No. 1245 discharging in straight stream position. Difficulty of determining what constituted good stream resulted in range of discharge from 300 to 367 gpmPowhatan hand line fog nozzle was tested in conjunction with heavy stream devices. Angle of 60 degrees, set by subcommittee provided discharge of 195 gpm

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Deputy Chief Vogt, chairman of the subcommittee, supervised all the tests in the entire series. Others assisting included: John Barman, chief engineer, Missouri Inspection Bureau, in charge of recording the discharge data and who later compiled the report figures and measured the angle of discharge on the photographs; Boyd A. Hartley, NBFU, in charge of nozzle settings and pattern angles; John Jablonsky, NBFU, nozzle settings; Fireman E. J. Tschiderer, Rochester, nozzle settings; Warren Y. Kimball, NFPA, report secretary and operations photography; Deputy Chief C. J. McMillan, nozzle pressure recording; Captain E. R. Starr, pump operator; Captain A. F. Reifstack, pump operator; Raymond J. Kubec, Akron Brass of Canada, pitot readings; Raymond E. Owen, Taylor Instrument Co., in charge of instrumentation; James Chisholm, Taylor Instrument Co., instrumentation; Hubert A. Walker, American LaFrance, observer representing the Fire Apparatus Manufacturers Association; and the author, discharge pattern photography.

References: John E. Barman, “Is the Water Really There?”, illustrated lecture, Proceedings, Fire Department Instructors Conference, Memphis, Tenn., March 1960; “Tests of Large-Capacity Spray Nozzles,” NFPA report, June 1960.

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