The CHEMICAL TECHNICIAN. WHAT H E DOES' OPERATIONS, DUTIES, AND S O P O R T A
1. Handling Dry Materials (a) Take samples (6) Store samples onvey materials
WHAT H E USES BQUIPMENT Cranes Drag lines Cars Pneumatic conveyors Car dumpers Trucks Stackers Skids Bins Hoppers Sheds Barrels Packages Drums Ooen storace degs Box and gondola cars Belts Screws Elevators Conveyors Solids pumps Redlers Pneumatic flight and vibrating conveyors Continuous samplers Automatic samplers Manual samplers "Thieves" "Samplitt"
MATERIALS 1. Character: Massive Lumpy Granular Powdery 3. Behavior: Corrosive Deliquescent Efflorescent
CALCULATIONS
DRAWING
Depending on material t o be handled or sampled 3ee A. S. T. M. meth-
Proper lettering, da
ods
Legibility and iermr
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2. Handling Fluids (a) Take samples (6) Transnort material .
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sure pumping, by kinetic pumping
3. Disintegration Prepare drymaterials and samples by crushing, grinding, pulverizing, shredding, chipping, and masiicating
Thief Piping Flumes and conduits Venturi gages Fans and blowers Jets Liquid gases Valves and fittings Pumps Pulsometers Blow cases Air lifts Jaw crushe'rs
Rolls Ball and hammer mills Ring roll mills Case mills chasers Hammer mills Ball and tube mills Stamps Colloid mills Ball and race mills Rod mills Attrition mills Buhrstone mills Grindstones Hogs and chippers Masticators
b c k s and ores :lay ?ibrous materials -0gs kraw
Tolwnes of tanks >pacity of pipes . Sse of handbo~kPhd charts ?low of water over V notch weir, 90 degrees 3pecific gravity of liquids
iead pipe convention 'Iant piping diagram
rime per unit per operation
Jnderstand drawing of varlons type of equipment, suc as assernhly, crosr -rctions, flow sheer. I)TM.CSS rllaeram: gage charts
Cime per unit per operation
Jnderstand drawing of various types a equipment, such a assembly, cross-sec tions, flow sheets process diagrams gage charts
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4. Mixing Materials By spraying, agitating, kneading, emulsifying. dispersing, and diffuslng
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Spray nozzles Turbine type dispensers Pumps, piping Valves Spray chambers Chasers
Contribution from the Committee on Non-Collegiate Chemical Education. OLIVE Chem . Met. Eng., 41,229 (May, 1934).
A "TRADE ANALYSIS"' R. E. BOWMAN Wilmington, Delaware
PHYSICAL AND MECHANICAL WHAT H E MUST KNOW --
SAPETY PRECAUTIONS
SCIENCE Surface weathering, oxidation of dry materials, such as sulfur Chemical properties of the substance and of equipment used in handline it Proper sampling A c t s process control Only homogeneous malerials are r c d y to be sampled Surfacc samples nrc unreliable
Sampling is a very responsible job which may lose money to the firm which is careless. I t should stand in court if necessary Need of rapid sampling to keep moisture content as near as possible t o "as received" basis Discrepancies between weights billed and weights received must be noted Angle of repose of dry materials How long sample must be kept Protecting purity of dry material; prevent waste and loss in the mass or in the sample Keep sample sealed t o settle controversy
Use of masks to protect from sili-
Pipe friction Viscosity and temperature as affecting fluid flow Acid proof cements Gaskets Corrosion of metals, pipes, and pumps Properties of materials Venturi gage principle
Need of jacketed piping for Liquids which would freeze in cold weather Types of couplings of pipes Properties of steam, compressed air Types of pumps Rapid sampling of volatile liquids
Colored pipes to indicate contents Danger of opening lines under Gressure or until drained Watch corrosive chemicals and ovoid excess pressure
Solubility influenced and increased by greater surface exposed t o solvent Colloidal state--grindability Intermolecular distances Quick quenching of hat materials Use of principle of "popping" corn (applied to wood fiber)
Know how fine a material needs to be for a definite use Test by sifting for per cent. completion of iob ~ e c o p d sof plant operation are important and must be kept accurately Nature of closed circuit disintegration Sound insulation
Guards on machinew-goggles, mask, and gloves for corrosive or siliceous material
Tendency of liquids to settle in layers in tanks if not mixed Effect of viscosity on mixing
Know when a mixture is homogeneous; this may require a laboratory report
Splash of corrosive or poisonous solutions t o be avoided Vapors may be corrosive or poisonous
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cosis and limev dusts.. eozeles " Shower after wo;k Sprinklers over piles of inflammable material Preventing skin disease from dust of certain nitro-compounds, and so forth Drum colors I. C. C. labels on drums, boxes, and cars Protection of workmen from waring and other sources of inj;ry Fire extinguishers First aid equipment
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WHAT H E USES
WHAT H E DOES OPERATIONS, DUTIES. AND SO FORTH
EQUIPMENT
CALCULATIONS
MATERIALS
DRAWING
Flight and screw mixers Tumbling barrels Ball mills Turbines Paddle and propeller mixers Coating pans Air-lift and air-bubble agitators Compressors Homogenizers Tanks, vats Diffusion cells
5. Control Temperatures Control heating and cool ing of reacting mate rials Control condensing a hot materials
6. Prepare Solutions By Leaching S Dissolving Extractine ~ercolating Washing Gas absorption
;pecific heats :hermometry Jse of handbooks *eat balances *laterial balances
Arc furnaces Resistance and induction furnaces Fuel fired furnaces Kilns Muffles Heat erchan~ers . Condensers Cement coolers Waste heat boilers Preheaters Diesels Process coolers Refrigeration equipment Spray ponds Cooling towers Steam jet units Centrifugal vapor units Compression and absorption units Surface and jet condensers Spray chambers Fractional condensers Fractionating columns Pumps
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Vats Paduca tanks Shanks tanks Woulff bottles Classifiers Ball, tube, and stamp mills Agitators Blowers Exhausters Tourills Thickeners Percolators
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jolids 2iquids-miscible immiscible
ant
Jnderstand diagram c equipment lead flow sheets
Engineering units a! contrastedwith labo ratory units o weight and measure ment
&b& and plate columns Diffusion cells Condensers SeDarators G& equipment Circulating pumps
7. Crystallize Materials from Solution
Ponds Vats Agitators Rotary and rocking crystallizers
rime t o allow maxi mum or optimun crystallization
Flow sheets
WHAT H E MUST KNOW
Mechanical hear, rlrrtriral heat, hear f r o m chetnica rncrgy through rurnl,n!.;rion and other rcac.rionz 1)in.m nnrl indirccr hearma Conduction, convection, and radiation heating an< cooling Non-evaporative cooling, evaporative cooling, hea transfer, laws of thermodynamics,qntropy Melting and freezing points Chemical and physical properties of refrigerants Air, water, spray, ice and refrigeration cooling Enerev level control ~ e a t s h formation f Exothermic and endothermic reactions Heat transfer surfaces Stream line flow of fluids Turbulent flow of fluids Dimensional analyses Flow a t right angles to tube hanks Insulation of vessels and pipes Nature of conductivity in solids, liquids, and gases Steam condensation Condensation of other vapors--mixed vapors Convection from finned or fluted surfaces Thermodynamic fundamenials Brine cooline Main refrigerants Corrosion of coils by hrine and refrigerants Carnot cycle Submerged cornhustion Heat transfer by organic compounds and by mercur vapor Heat emission (radiation) from surfaces Ternoerature madients
'rotection of furnaces aeainst over. heating !onservation of waste heat; use of mer cury, oil, and other substances when direct heat is dangerous Jse of handbooks to secure necessan data 'rotection of coolers against freezinl weather, proper regulation
?rotection of eyes and body from heat and cold-wool clothing ?recautions against electrical shock Masks for use when SO*, CIS, or ammonia lines, and SO forth. break
Henry's law Solutions and their properties of continuous extractiw, se -Removal ~ - solubles ~ ~ bv ~ ~ mathematics Distribution of a salute between two solvents Effect of surface area of solute Washing one liquid with another Leachine. dissolvine. extraction. percolation, washing gas a&orption
Xsposal of insoluble residues Nashing insolubles free from desired o undesired solubles (see Filtration) iolvent recovery problem, how handle
rain size of crystals Jse of non-corrosive vessels Nashing mother liquor from crystals
Guard against danger of inflammable~or toxic solvents
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40 m.
WHAT H E DOES OPERATIOSIS, DUTIES, AND SO FORTH
8. Vaporize Liquids and Solids: By Distilling Eva~oratir lg ~rylng Subliming
9. Melt Solids and Freeze Liquids
10. Control Adsw)tion (See Separatio)0 )
11. Control Electtical Separation Magnetic Electrostatic Electrophoric
12. Control Filtrai:im (See Operation1 6)
13. Control Seretxing and Sieving
EQUIPMENT Salting evaporators Vacuum crystallize! Grainers Suhlimers Pumps Coliumns Tanks Kettles Evaporators Separators Continuous stills Pot stills Receivers Furnaces Kettles Crucibles Reaction equipmen Molds Solid COEpresses Refrieeration eal me% Char and contact ters False bottoms Agitated tank Packed towers
Magnetic pulleys chutes H k h intensity sep:
