EQUIPMENT
BOTH SIDES AT ONCE. Particles leaving the Stajet nozzle travel onto both sides of steel mesh simultaneously. The new electrostatic sprayer for coating with dry powders has other advantages also, according to the maker, SAM ES
Electrostatic Coater Sprays Dry Powders SAMES unit coats mildly conducting surfaces with relatively nonconducting powders; many powders and substrates can be handled An electrostatic sprayer that applies dry powder coatings to a variety of substrates has made its formal U.S. debut. Developed by SAMES (Société Anonyme de Machines Électrostatiques), Grenoble, France, the unit, called Stajet, is being marketed in the U.S. by SAMES USA, Inc., New York, N.Y., a wholly owned subsidiary. The sprayer can coat any surface that's at least mildly electrically conductive with any relatively nonconducting powder, according to SAMES. After being sprayed, the coatings are oven-cured, if needed. Compared to liquid electrostatic and conventional coating methods, dry electrostatic spraying has a number of advantages, the firm says: • Material utilization is nearly 100%. 42
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Unused powder can be recycled and reused without treating. • Coatings are uniform, even in irregular and complex shapes. • Coatings up to 20 mils thick can be made on a cold surface in one pass. • Coatings can be made pinhole-free and don't depend on wetting. In addition, there are no toxic or flammable solvents. Spray booths aren't needed, and there is no setup time. Also, the systems can be readily automated. According to SAMES, Stajet can handle "countless" types of powders, as long as they are relatively nonconducting (volume resistivity greater than 100,000 ohms per cm.). Acceptable particle size range is 70 mesh
to 325 mesh or finer. Examples include plastics, such as PVC, polyethylene, Teflon, cellulosics, and polypropylene; dry epoxies; talc; vitreous frit; and metallic oxides. Substrates, too, run a wide gamut. The only restriction is that they be at least mildly conductive to electricity. Surfaces successfully coated include metals, glass, heated ceramic, heated plastics, and moist paper and cloth. The coating doesn't stay on indefinitely. But it will stick long enough for the coated object to be put in an oven for curing. Conveyor line vibration won't shake the particles off under normal conditions, SAMES says. Uses range from decorative applications to coating electrical and electronic components. Stajet can also handle interior coatings on objects such as pipe, valves, and strainers. The firm says that it has successfully coated interiors of pipe 3 1 / . , in. i.d. by 12 in. long to 12 in. i.d. by 36 in. long. How It Works. The unit puts a high voltage (90 kv.), low amperage (0.2 ma.) negative charge on the powders. Mild air pressure (0.3 to 1.5 p.s.i.g.) feeds the charged particles through a spray nozzle. The particles leaving the nozzle are attracted to any electrically grounded object in front. SAMES explains the effect by using what it calls the "image" theory. The negatively charged particles "see" their oppositely charged particles on the opposite side of the grounded object. They are thus attracted to the surface. Particles must be nonconductive, since otherwise current would flow between particles and object to ground and the particles wouldn't stick. On the other hand, if the surface were an insulator, there would be little attraction. It would quickly reach the same potential as the gun, and particles would be repelled by their like charges. Until the coating is so thick that a dielectric barrier is raised, the particles continue to look through to the ground object, seeking thinly coated or bare areas. This explains why Stajet coatings are uniform with few pinholes, SAMES says. System Is Safe. SAMES stresses that despite the high voltage, the low current makes the system harmless. An operator can safely spark the unit to his body, the company says. The new technique has several tricky angles. For example, in addition to conventional masking, electro-
monitoring
...across the spectrum with just a turn of a D I A L Now with just a turn of a dial you can continuously monitor column effluent for compounds absorbing at any wave length in the ultraviolet spectrum. Vanguard's all-new Model 1056 Automatic UV Analyzer performs with greater sensitivity and versatility than ever thought possible. Dualbeam operation utilizing sample and reference cuvettes provides continuous base line compensation for gradient elutions and for other applications where the optical density of the eluent may change. Operates with minimum super vision and compatible with all Fraction Collectors. A u t o matic chart recorder marking system speeds identification by quickly and accurately locating test tubes in which absorbing materials are located.
To learn how you can save time while assuring positive identifications—even in the presence of highly absorbing solvents—write direct for complete details on the new Vanguard Model 1056 Automatic UV Analyzer. • Analyzes across the spectrum—from 200 to 400 milli microns • Particularly well-suited for gradient elution techniques^· even when highly absorbing solvents are utilized • Monochromator-coupled hydrogen light source permits selective dialing across UV spectrum • Automatic chart recorder marking system locates ab sorbing materials by test tube • Compatible with all Fraction Collectors—regardless of make or model • Fully transistorized for long, precision service
VANGUARD INSTRUMENT COMPANY
DESIGNERS AND MANUFACTURERS OF PRECISION INSTRUMENTATION FOR RESEARCH P.O. Box 244 · LaGrange, Illinois · Fleetwood 4-5656 Regional Offices: New York, New York, 520 Fifth Avenue, TN 7-1998; San Francisco, California, 115 New Montgomery Street, EXbrook 2-0511 C&Ε Ν
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you'll wash them better with.
Blockson Polyphos The highest phosphate content, w a t e r softening capacity a n d solubility of all the sodium phos phates. That's Polyphos, the Blockson brand hexametaphosphate. Provides buffered pH—at optimum detergency—throughout the w a s h cycle. Softens b y sequestration, so doesn't consume y our formulation's
other cleaning agents, "infinite solubility"—use all the Polyphos you wish if your idea is high efficiency plus mildness. Yet its 67% P2O5 content gives you room for EXTRA alkali, if that's your plan. Poly phos is a top peptizer a n d synergist. Write your Olin district office for a sample and data bulletin.
Modern Detergents Mean Phosphates and Phosphates Mean Blockson
CHEMICALS DIVISION O l i n M a t h i e s o n C h e m i c a l C o r p o r a t i o n · Joliet, I l l i n o i s · DISTRICT OFFICES: Atlanta · Buffalo Charlotte · Chicago · Cincinnati · Houston · N e w Orleans · N e w York · Philadelphia · Providence · St. Louis 44
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static masking with secondary ground planes can often be used. And an un grounded surface can be used as a re flector to coat both near and far sides of an object, such as wire mesh, at the same time. Stajet's coating rate is 30 to 40 lb. per hr. This corresponds to laying a 3-mil coat over 1 sq. ft. in one second. Air consumption is 3 cu. ft. per minute at 45 p.s.i.g. An entire outfit, includ ing a SAMES 90-kv. electrostatic gen erator, weighs less than 70 lb. List price is $2875, f .o.b. New York. The new technique appears to com plement the fluidized bed coating method. Several companies, including Polymer Corp., which has a licensing agreement with Knapsack Griesheim A.G., Cologne, West Germany, and Armstrong Products Co., make fluid ized bed equipment.
In this process, the object to be coated is preheated above fusion tem perature of the resin powder. Then it's dipped for a few seconds into a fluidized bed of the powder. Finally, the object is oven-cured. Electro static spraying can handle large ob jects such as automobile bodies more easily. And it's better for thin coat ings, according to SAMES. Ε 30
BRIEFS New butterfly valve is available from Crane Co.'s Industrial Products Group, Chicago, 111. Teflon-glass fiber bear ings, inboard and outboard, full length and diameter, reduce torque and in crease valve life over that of conven tional units. Operators can be easily interchanged, the company says.
June 4, 1962
Readers' Information Service
Rated for 200 p.s.i. at 200° F., the valve comes in wafer and two-flange types and in five sizes—3, 4, 6, 8, and 10 in. Ε 31
Electronic mode control for real time and repetitive analog computers is now being offered by Computer Products, Inc., Manasquan, N J . The control unit provides switch selection of reset, hold, and operate periods in 0.1-millisec. steps. The solid state units are available separately or as expansion modules for updating existing equip ment. Ε 32
Newly designed series of centrifugal type Β fans from Chicago Blower, Franklin Park, 111., have top motor mounts and adjustable housings. Iden tified as Design 10, Arrangement 3T, the fans come in sizes from 12 1 / 4 -in. through 30-in. diameter. Larger sizes will deliver up to 19,000 cu. ft. per minute of air, according to the com pany. The units are intended for in dustrial ventilation and air condition Ε 33 ing.
Use this handy self-mailer to obtain further information or literature. Simply mark the items desired, fill out the information requested, clip the coupon, fold, staple, and mail.
Hot and cold wall autoclaves for use
Name: Company: Street: City
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Your Title: Your Function (Check One): 1 2 3 4 5
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Corporate Management Technical Management Product Research Product Design & Development Process Research
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Process Design & Development Production—Processing Purchasing Analysis—Testing Consulting
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Your industry: 1 Π Construction 2 Π Food & Kindred Products 3 Π Textile Mill Products 4 Π Paper & Allied Products 5 Π Printing, Publishing, etc. 6 Π Chemicals & Allied Products 7 Π Plastics; Synthetic Resins 8 • Drugs 9 Π Soap, Detergents, Cosmetics 10 Π Paints, Varnishes, etc.
\\ Q Petroleum Réf., Asphalts, Lubricants 12 Π Rubber; Plastic Products 13 Π Leather & Leather Products 14 Π Stone, Clay, & Glass Products 15 • Primary Metal Industries 16 Π Fabricated Metal Products 17 Π Machinery & Equipment 18 • Transportation Equipment 19 Π Instruments 20 Π Education
in gas pressure bonding have been in troduced by Autoclave Engineers, Erie, Pa. The units are designed pri marily for bonding metal to metal, operate at up to 15,000 p.s.i. and 1570° C. The cold wall models are for use for high temperature bonding studies at high pressures; the hot wall models are for use where extremely high temperatures are not critical, the firm says. Ε 34
Electron beam test furnace has been developed by Stauffer Metals Division of Stauffer Chemical Co., Richmond, Calif. The furnace is being produced and marketed by Gilliland Instrument Co., Oakland, Calif. According to the companies, materials such as steels, super alloys, refractory metals, graph ite, and cermets can be raised to tem peratures over 6000° F. in 1 sec. and held constant for hundreds of hours. Ε 35
Further useful information on keyed Equipment items men tioned is readily available . . .
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