DEPARTMENT OF ENGINEERING RESEARCH UNIVERSITY OF MICHIGAN ANN ARBOR Report on DUST-REMOVAL EFFICIENCY OF SCHNEIBLE MULTI-WASH DUST COLLECTOR by HUGH E. KEELER Assisted byH. C. Braun R. L. Eshelman F. E. King Project Number 1M72 for CLAUDE B. SCHNEIBLE COMPANY 2827 Twenty-Fifth St., Detroit 16, Mich. July-December, 1936

The DUST REMOVAL EFFICIENCY of SCHNEIBLE MULTI-WASH DUST COLLECTORS The purposes of this series of tests were as follows: 1. To determine the dust-collecting efficiency of a Schneible "Multi-Wash" Dust Collector installed to serve Molding Equipment Unit No. 6 in Building No. 70 of the Buick Motor Co., Flint, Michigan. Building No. 70 is one of the important buildings in the large foundry group and the No. 6 molding equipment unit is the newest and of the most advanced design. The dust-collector is nominally rated at 30,000 cubic feet per minute and was designed, manufactured and installed by the Claude B. Schneible Company, 3951 Lawrence Avenue, Chicago, Illinois. It is a heavy-duty, high-efficiency type for handling air very heavily laden with dust and other impurities. 2. To determine the amount of dust in the air at the following locations: (a) At the breathing-line (nose-level) of each of the two operators at the shake-out of the No. 6 molding equipment unit. (b) To determine the amount of dust in the air at the position 9 feet behind the two operators at the shake-out on No. 6 molding equipment unit and midway between them. These samples were taken at the breathing-line (nose-level), above the foundry floor. GENERAL DESCRIPTION oF DUST COLLECTOR and CONDITIONS oF OPERATION Figs. Numbers 1 to 10, inclusive, which follow are descriptive of the dust-collector installation and of the service conditions under which it operates. Fig. 1 shows the Schneible Multi-Wash Dust Collector on which these tests were made. It is of the heavy-duty type and is rated at 30,000 cubic feet of free-air per minute. It serves the No. 6 Molding Unit which is a thoroughly modern, highcapacity, line-production unit. This includes the shake-out and other devices required in the operation of this unit such as sand-rammers, core-grinders, etc. Fig. I. A 30,000 C.F.M. Schneible Multi-Wash Dust Collector at Buick Motor Company, Flint, Michigan, serving their No. 6 Molding Unit. Fig, 2. A Schneible Truck-Type Multi-Louver Dewatering Tank installation at a large Automatic Castings Plant. US T h S C H N E I B LE "M U L TI - W A S H WE T METHOD page two

At the time of these tests the No. 6 Molding Unit was producing two (2) Oldsmobile cylinderblocks per minute; a very high rate of production. As shown, the collector is installed outdoors. The outlet from the collector is the inclined duct leading downward through the building wall where it enters the centrifugal suction fan. This centrifugal suction fan discharges into the atmosphere through the exhaust-head shown above the roof. Fig. 4. The Shake-Out on No. 6 Molding Unit at Buick Motor Company where some of the tests described herein were made. Fig. 3. The sludge disposal basin for No. 6 Molding Unit at Buick Motor Company's Flint, Michigan Foundry. Figs. 5, 6, 7, and 8 are various types of coregrinders. The dust'disposal from these is a very difficult problem and gives some idea of the heavily dust and silica laden air that is passed into the dust-collector. Fig. 9 shows the compressed-air operated airejector which was used to operate the impinger which collected the dust samples taken at the outlet from the dust-collector. The person appearing in this photograph is the writer. Fig. 10 is a photograph of the apparatus used in making the tests. Fig. 5. A Core Finishing Station at Buick Motor Company showing method of ventilation. Fig. 2 is a view of a Truck-type Multi-Louver Dewatering Tank. Fig. 3 is a view of a sludge disposal basin. Fig. 4 is a view at the shake-out on the No. 6 Molding Unit where some of the tests were made. Fig. 6. Finishing Cylinder Barrel Slab Cores at Buick Motor Company. W. s I MIIr A I II ( USE T h e S C H N E I BLE "M U L T I WA S H W E T M iE U) page three

APPARATUS USED IN TEST The important pieces of apparatus used in these tests are shown in Figure 10, page 4. The conditions under which these tests were made were such that it was not possible to obtain good photographs at the time of the tests, consequently the various pieces of apparatus as used were grouped together and photographed in the Mechanical Engineering Laboratories of the University of Michigan. Fig. 9. Hugh E. Keeler Iith the compressed air operated air-ejector which t as used to operate the impinger which collected the dust samples taken at the outlet from the Dust Collector. Item (2) This is a sampling flask fitted with a Greenburg-Smith impinger which is shown connected by rubber tubing to the calibrated, compressed-air operated air-ejector shown at (3) and to the glass pitot dust-sampling tube shown at (4). Item (3) This is a compressed-air operated air-ejector, equipped with a calibrated metering orifice. This is used for drawing the dust-samples from the duct through the glass pitot sampling tube shown at (4); then the impinger shown in the flask at (2); then through the metering orifice contained within the ejector assembly. Fig. 7. A core finishing job that creates some of the heavily dust and silica laden air that passes into the Dust Collector. Fig. 8. A4nother core finishing station that is tied into the Collector System discussed is that shown above. Item (1) This is a Greenburg-Smith DustSampling Set comprising 10 standard sampling flasks and 3 Greenburg-Smith impingers. The whole group is mounted in the carrying case as shown. fig. 10. Photograph of apparatus used in making the tests. U S T h S S C H N E I B L E M U L TI - W AS H" WE T METHOD page four

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Item (4) This is a glass pitot-tube used for withdrawing dust-samples from the duct. Item (5) This is a standard wet and dry-bulb thermometer set for the determination of relative humidities. Item (6) This is a standard ABC pitot-tube used for determining duct velocities. It is shown located in a duct together with a device for making horizontal and vertical traverses. In the actual tests this device was not used; the horizontal and vertical traverses being made by hand-positioning the pitot-tube. Item (7) This is an oil-filled slant-gage used for determining velocity pressures in the duct. Item (8) This is an oil-filled slant-gage used for determining static pressures in the duct. Item (9) This is an oil-filled manometer used for determining total pressures in the duct. Item (10) This is a supply of distilled water for use in the sampling-flasks. Item (11) This is the microscope used for making the dust-count determination. On the stage may be seen an Adams Approved Counting Chamber with Improved Double Neubauer Ruling. Item (12) This is a Short & Mason, Precision, Aneroid Barometer used for determining atmospheric pressures. TESTING EQUIPMENT and APPARATUS The dust samples were collected by means of Greenburg-Smith dust-impingers, together with the necessary compressed air operated air-ejectors and metering orifices. The samples of the dust-laden air were obtained by traversing the inlet and outlet ducts with specially constructed glass pitot tubes. The inlet-duct was also traversed by means of a standard pitot-tube to obtain data for determining the air quantity entering the Multi-Wash Dust Collector in cubic feet per minute. An adequate quantity of calibrated distilled water was provided. Dust counts were made in a light field by means of an approved Neubauer Counting Chamber and a magnification of 100 X was used. Relative humidity at the collector discharge was determined by the usual weet-and-dry bulb psychrometer. Relative humidity at the entrance to the dust-collector was determined by means of a Friez Motor-Driven, Precision, Aspirating Psychrometer. Barometric pressure was determined by means of a Short & Mason, Precision Aneroid Barometer which was carefully checked. All duct pressures were determined by means of calibrated, oil-filled, vertical and slant draft-gages. Refer to Fig. 10 preceding and accompanying legend for further details of the apparatus used. METHOD of CONDUCTING TESTS The testing routine for determining the dustremoving efficiency is described in the following: The duct system which collects the dust-laden air from the shake-out and from the foundry was studied and a straight horizontal run was chosen as the most suitable place at which to collect the required dust-samples and to determine the quantity of dust-laden air passing into the collector. Two holes, 90~ apart were made in this duct so that horizontal and vertical pitot tube traverses could be made in the usual manner. Similar provision was made for pitot-tube traverses in the horizontal duct connecting the outlet of the Multi-Wash Dust Collector with the suction' of the centrifugal blower which discharged into the atmosphere. The diameter of the inlet duct to the collector and the diameter of the outlet duct from the collector were next carefully determined at the locations where the pitot-tube traverses were made. Next the pito-t-tubes were marked so that they could be located at the two mid-points of five concentric, annular equal areas on a horizontal traverse and also on a vertical traverse, thus giving a total of 20 points and at which readings of pressure were taken and at which dust-laden air samples were removed from the duct. Prior to the collection of the dust-samples a traverse of the ducts leading into and out of the collector were made and readings of total, static and velocity pressure were made. From these data the average velocities were determined and also rates of the flow of dust-laden air in the ducts in cubic feet per minute were determined. On the basis of these determined velocities, glass pitot-tube sizes were chosen such that the average velocities of the dust-laden air through them were as closely equal to the velocities of the dust-laden air in the ducts as possible. This was essential in obtaining proper samples of the dust-laden:i in the ducts. After these determinations ha been made the traverses at the Multi-Wash Dust Collector inlet and outlet were made. The pitot-tubes were left at each station for two (2) minutes so that the total time of dust collection for each traverse was forty (40) minutes. Two men (four in all) were required to make the traverses at the inlet and two men at the outlet from the collector. Each pitot sampling tube discharged into a Greenburg-Smith impinger type of dust-sampler. The necessary suction for operating each impinger was furnished by a jet-type of airejector which was operated by compressed-air from A. - -... US E Th e S CH N E I BLE " M U L T I - WAS H" WE T METHOD page five

the compressed-air service lines in the foundry. The rate of air-flow through each impinger was determined by means of a calibrated orifice with rounded approach which was incorporated as a part of the ejector assembly. Air pressure gauges on each airejector were maintained at a constant value, this value lying between the limits wherein the orifice passed a definite quantity of air. The rate of flow of air through each orifice was carefully checked. Air temperature in the inlet duct at the point of traverse was determined by a high-grade, mercuryin-glass thermometer. Barometric pressure, relative humidity at the collector inlet and relative humidity at the collector outlet were determined as rioted previously. All distilled water used in the impingers and for subsequent dilution of samples was subjected to a control count. The method of making the actual dust-counts has been described previously. Analyses of the samples collected in the impingers were made for quantity of total solids and for quantity of silica; (SiO2). These quantitative determinations were made in the Chemical Laboratories of the Department of Engineering Research of the University of Michigan. It is worthy of note that during these tests the No. 6 Molding Equipment Unit was operating at a very high rate of production and was turning out two (2) Oldsmobile cylinder blocks per minute. RESULTS of TESTS TABLE No. I 0 C) 0,O( Col. A Col. B Col. C Col. D Col. E.r4. _,. a 2. Average total pressure; inches H................-1.912 -5.97 - 3. Average static pressure; inches H..............-2.592 -6.59 - _ 4. Average velocity pressure; inches HO........0.601 0.62 - 5. Barometer; inches h g.. 29.410 29.410 29.410.5 c NO b? a S.1 >> 7. Wet-Bulb; F~..71.0 60.5 60.5 60.5 58. Relative humidity; per cent.. 95.0 41.1 41.1 41.1 9. Air Velocity; feet per minute........................ 3322.4... Col. A Col. B Col. C Col. D Col. E 10. Air per minute; cubic feet.28.994.... 1I. Millions of dust particles per cu. ft. of air..2976.4 11.02 1.51 5.04 7.57 12. T otal solids per cu. ft.re; inches.............. 0.021171 - 0.000354 3. Totalverage solids per cu. ft. of air;re; inches.............. -2.592 0.0000008 14. Total silica (SiO2) per cu. ft. of air; grams 0.010910 0.000038 - - 0.000042 15. Total s ilica (SiOty per cu.re; inches....... 0.000024 0.00000008 0.00000008 5. Barometer; inches hg....................................... -. 29.410 29.410 29.410 6. Dry-Bulb; F0...................................... 129.0 72.0 75.5 75.5 75.5 16. Wet-Bulbc (SiO; per c e nt........................................ 1. 60.5 60 60.5 17. A ll other solidity; per cent.............................. 9548.47 88.81 41.1 41.1 1.1 9. Air Velocity; feet per minute............................ 3322.4 18. Fan sper minute; cubic feet................................ 28.99444 444 444 444 444 11. Millions of dust particles per cu. ft. of air.... 2976.4 11.02 1.51 5.04 7.57 12. Total solids per cu. ft. of air; grams.............. 0.021171 0.000341 - - 0.000354 13. Total solids per cu. ft. of air; Ibs..................... 0.000047 0.0000008 - - 0.0000008 14. Total silica (SiO, per cu. ft. of air; grams.. 0.010910 0.000038 - - 0.000042 15. Total silica (SiO,) per cu. ft. of air; Ibs....... 0.000024 0.00000008 - 0- 0.00000008 16. Silica (SiOO); per cent........................................ 51.53 11.19 - - 11.76 17. All other solids; per. cent.................................. 48.47 88.81 18. Fan speed R.P.M................................................. 444 444 444 444 444 19. M otor speed R.P.M............................................ 1164 1164 1164 1164 1164 DISCUSSION of TESTS In conducting these tests every effort was made through the collector. Before passing through the to obtain truly average dust-sampleg and likewise collector the silica (SiO2) is 51.53% by weight of every effort was made to obtain truly average dust the total solid material and after passing through counts. the collector the silica (SiO2) has dropped to It is of interest to note the high-dust removal 11.19% of the total solid material that has passed efficiency, based on number of dust-particles of through the collector. 99.7%. ~~~99. ~~~7 /~%v~..This is a point of much importance. It is also of importance to note the great decrease in the ratio of silica content by weight in Attention is particularly directed to the results addition to its great drop by weight after passing appearing in Table No. 2 on page seven.,,, _,...,,, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ USE T h * S C H N E I B L E M U L T I-WAS H' WET METHOD page six

RESULTS of TESTS TABLE No. 2 The principal test results given below are all expressed in terms of air at the conditions in the foundry which were: Barometer===29.410 inches of mercury Dry-bulb temperature-75.5~F. Wet-bulb temperature-=60.5~F. Relative humidity=41.1% Col. A Col. B Col. C Facing Wall; 9 ft. Behind Operators In D In Duct at Duct Shake-out; 1. Location....-.. —------- ---------------- Entrance to Discharge From Midway between; Dust Collector Dust Collector At Breathing-Line Above Foundry floor. No. 6 Molding Unit 2. Millions of dust particles per cu. ft. of air............. 3294.9 11.11 7.57 3. Total solids per cu. ft. of air; grams.............................. 0.023436 0.000344 0.000354 4. Total solids per cu. ft. of air; pounds................ 0.000052 0.0000008 0.0000008 5. Total silica (SiO2) per cu. ft. of air; grams............ 0.012077 0.000038 0.000042 6. Total silica (SiO2) per cu. ft. of air; pounds.............. 0.000027 0.00000008 0.00000008 7. Silica (SiO2) in per cent; by weight.................... 51.53% 11.19% 11.76% 8. All other solids in per cent; by weight............. 48.47% 88.81% 88.24% 9. Total solids per cu. ft. of air; grains................. 0.364000 0.005600 0.005600 10. Total silica per cu. ft. of air; grains................. 0.189000 0.000560 0.000560 11. (Item 9)-(Item 10) per cu. ft. of air; grains.......... 0.175000 0.005040 0.005040 NOTE:-1 pound==7000 grains / 32949-11.11 1 Dust removal efficiency based on number of dust particles= 3294.9 x 100%-99.7% TABLE No. 3 All values below estimated by means of ruled counting grids: Col. A Col. B In Duct at In Duct at 1. Location........ Entrance to Discharge from Dust Collector Dust Collector 2. Percentage of particles between 10 and 15 microns; longest dimension..-........... 1 Negligible 3. Percentage of particles between 2 and 10 microns; longest dimension............... 35 15 4. Percentage of visible particles below 2 microns; longest dimension................ 64 85 1 Micron = 0.001 millimeter.,,,,,,, i i,,~~~~~~~~~ USE T h e S C H N E I BLE "MULTI W A S H WE T METHOD page seven

[ COMMENTS ON THE FOREGOING TEST by the ENGINEERING DEPARTMENT of the CLAUDE B. SCHNEIBLE COMPANY The U. S. Public Health Service in its Bulletin No. 187, July, 1929, defines the probable safe condition with reference to air-borne dust as one in which the concentration of dust particles measuring 10 microns or less, in the greatest dimension, does not exceed 20 million per cubic foot, and that the free silica (quartz) concentration shall not exceed 25% to 35%. The Code of the Industrial Commission of Wisconsin states that the Commission, its advisory committee, employers and scientists have agreed on a tentative figure of 15 million countable dust particles under 10 microns in longest dimension with free silica content of 35 per cent in a cubic foot of air as determined by United States Public Health Service technique. Variations in free silica content will make proportional inverse changes in this standard. In the case of practically pure silica the permissible dust count would be 5,250,000 countable particles. By countable particles is meant those particles within the range of size from 2 to 10 microns in the longest dimension. Dust particles smaller than 2 microns in the longest dimension are not ordinarily countable. Dust particles larger than 10 microns in longest dimension do not ordinarily reach parts of the body where they can produce injury. In the study made, the air at the inlet to the Dust Collector showed a total dust concentration of 3,294,900,000 particles per cubic foot made up of particles in the following size groups: Particles measuring in excess of 10 microns..................... 1% Particles measuring between 2 microns and 10 microns...............35% Particles measuring less than 2 microns.....-...................64% Further analysis of this dust showed it to- contain in excess of 51% silica. Now, let us examine the air leaving the Dust Collector. The total number of particles per cubic foot is 11,110,000, all of which measure 10 microns or less in the greatest dimension and not only has the number of particles been reduced by 99.66%, but the silica content has been reduced by 99.67%. This reduction of dust concentration has rendered what was a particularly hazardous dust concentration to one which to the best of our knowledge is practically harmless, and one which compares quite favorably with the atmospheric dust conditions in many of our big cities. In 1936, the U. S. Public Health Service in its Bulletin No. 224 entitled "Atmospheric Pollution of American Cities for the Years 1931-1933," we find that the average dust concentration in fourteen cities studied was 23,078,110 particles per cubic foot; the range being between 42,871,000 and 9,581,000. It will be seen from this that the air leaving the Multi-Wash Collector contains far less dust than the average city air. -j page eight

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