This section was written by Senior Editor Michael Valenti
Fluid Power and Fluid Handling

Technology Focus part 1

Precision Spray From Pizza to Bottles The air atomizing nozzles from the Spraying Systems Co. of Wheaton, Ill., are designed to deliver precise and consistent industrial spraying for applications ranging from bottle manufacturing to pizza making. Pressurized liquid and compressed air are fed into the nozzle, forming various spray patterns composed of droplets as small as 15 microns outside the nozzle body.

The Spraying Systems air atomizing nozzles use pressurized liquid and compressed air to deliver fine, consistent sprays.

For example, a beverage bottle maker in Texas uses Spraying Systems' 1/8JJAU air atomizing nozzles. Six of them are mounted on a traverse bar to apply a wax and water coating on its bottles after molding. This coating helps prevent breakage during handling, filling, labeling, and transportation. This spray system is typically used with the SUJE compact flat spray air atomizing nozzle from Spraying Systems, which was designed to eliminate variations in liquid flow caused by fluctuations in the air line, thus providing a more precise and consistent spray.

A midwestern food processor used the system to apply a light, even coating of potassium sorbate, a mold inhibitor, to the top and bottom of packaged pizza crusts. The spraying system was equipped with regulators to adjust both air and liquid pressure, and to achieve the requisite droplet size.

Producing High-Purity Acids for Electronics
The semiconductor industry demands ultrapure acids to etch and clean microchips for computers, pagers, telephones, and other electronic equipment. Pacific Northwest National Laboratory of Richland, Wash., worked with Viatec Recovery Systems, also of Richland, to design a new system to produce ultrapure acids. This system is being used by Koch Microelectronic Service Co. of Bryan, Texas, to produce hydrochloric acid with purity ranging from 100 parts of metal per billion to 100 parts per trillion.

Koch Microelectronic first approached Viatec to design a system that could convert industrial grade hydrochloric acid, which contains metal concentrations of one to 10 parts per million, into an ultrapure product. Viatec made use of Pacific Northwest's modeling capabilities and specialized testing laboratories to design the new acid recovery system. Viatec and Pacific Northwest worked on the project through the summer of 1998, and delivered the system that fall.

The system uses components made of high-purity fluoropolymers, joined by butt fusion, a technique that is used in semiconductor manufacturing. Briefly, this involves using an infrared platen to heat tube ends, so that they fuse when they come in contact with one another. These measures minimize impurities.

Industrial grade hydrochloric acid is continuously fed into the purification system's recirculating acid stream. This heats the acid to 240F to 250F, generating a purified hydrochloric acid vapor that rises from the metals and other contaminants, which remain in the recirculation stream. The acid vapor is passed through a demist-er column where residual droplets are removed. The resulting metal-free vapor is then condensed and collected as ultrahigh-purity hydrochloric acid.

The acid recovery system enables Koch Microelectronic to package the ultrapure acid in a variety of containers, from drums to tank wagons, and to adjust acid strength to meet specific client needs. Since the Koch Microelectronic installation, other acid recovery companies have inquired about purchasing similar systems to produce ultrapure hydrochloric and other acids, such as nitric, used in electronic manufacturing.

Finer Filtration
Dynaflow Inc. of Fulton, Md., designed its Dynaperm filtration system to remove suspended solids from industrial and municipal wastewater and other liquids. The U.S. Navy has used a prototype for filtering heavily silted seawater and river water before rendering it potable. Cavi-Tech of Atlanta has used another unit to remove the paint particles from water sprayed at high pressure to strip vessels and bridges.

The Dynaperm filter tube system employs several phenomena to remove suspended solids from industrial wastewater.

Dynaflow adjusts the size and structure of the micron-scale pores of its filtration tubes during the manufacturing process to suit their application. The company also selects the extrudable thermoplastic appropriate to the liquid being treated.

As effluent passes through the Dynaperm filters, solid particles are slowly driven toward the porous tube walls by the permeating flow. Then, according to the company, as more particles are concentrated on the tube walls, the turbulent diffusion of the particles from areas of high concentration to low concentration creates a "dynamic membrane" near the walls that allows only extremely fine particles, much smaller than the pore sizes, to cross the filter. In addition, the geometry of the flow chamber creates a swirling effect around the tubes, and a controlled periodic flow interruption is imposed.

Beyond improving filtration efficiency, these forces cause the particle layer built up on the porous tube walls to be shed periodically and to settle at the bottom of the tube in the form of sludge. A built-in backwash channel removes the sludge.

Intelligent Valve Optimizes Flow Control
It seems that a new smart control valve has caught the attention of some system designers. KSB Armaturen GmbH of Frankenthal, Germany, introduced its BOA-Control IMS flanged flow measurement and regulation valve last March. It is designed to measure the cooling or heating flows of large buildings on site within seconds.

Suddeutsche Etna of Munich incorporated the BOA-Control valves into the heating and cooling system it designed for the German Embassy in Tunis, and Sulzer Infra of Stuttgart used the valves in the temperature control system it built for the new Coca-Cola facility in Timisoara, Romania.

The speedy measurement derives from the multifunctional sensor integrated with the valve. The sensor is linked to a pocket-sized computer by an electric cable. Conventional measurement valves use two pressure measurement tubes.

As a result, the BOA-Control IMS can measure flow accurately across the entire range of valve travel, even while the handwheel is being moved, independently of the valve disc position and minimum differential pressure.

Because heating and cooling measurement valves are often insulated, it can be difficult to read identification on their bodies. During startup, the smart valve shows the nominal diameter of the connected valve on its computer display. The operator can choose either to look at the current flow rate, in cubic meters per hour, or the temperature, displayed in degrees Celsius. This data helps operators or contractors check the volume flows in hot water heating systems and cold water air conditioning systems.

The BOA-Control IMS also can be used as a shutoff valve. This capability can serve to reduce the number of measurement and regulation valves needed in a heating or cooling system. Operators can return and set the valve to its original position after shutoff by using a travel stop with protective cap.

Powerful Pulses
Federal and local environmental agency restrictions on dust emission drive the installation of baghouse dust collecting systems. These are basically steel or aluminum enclosures containing bag-shaped filters that collect the dust from dirty air. The filters are cleaned by periodic bursts of air that are provided by pulse valves.

The multifunctional sensor of the BOA-Control IMS valve can measure flow accurately across the entire valve travel range in warm water heating and cold water air conditioning applications.

Automatic Switch Co. of Florham Park, N.J., designed its new Power Pulse valves to deliver those bursts of air with improved flow, to better clean the filters. The valves are aimed at manufacturers of baghouses used by coal-fired power plants, concrete plants, and pharmaceutical process- ing plants.

ASCO designed the Power Pulse valve body without obstructions, to increase the volume per pulse and generate higher peak pressure. The valve also incorporates a springless, one-piece piston/diaphragm that extends service life and provides fast opening and closing times. In addition, the Power Pulse valve includes an interlocking body and bonnet with clip ring that facilitates access for maintenance.

The Power Pulse valves are operated by integral-pilot or remote-pilot solenoid valves. In either case, the pilot valve is energized when pulsing is required so that pressure above the pulse valve's diaphragm is relieved. This causes the main line pressure under the diaphragm to open the valve and send a blast of air to clean the baghouse filters.

home | features | news update | marketplace | departments | about ME | back issues | ASME | site search

1999 by The American Society of Mechanical Engineers