Hand-held

Block diagram for a filter photometer with photo showing a typical hand-held instrument suitable for field work. Colorimeterrw is manufactured by Hach Company/photo courtesy of Hach Company. 

The hand-held comparative Brinell tester is the most portable device. With this device a hammer blow is substituted for the static load which is transmitted first through a standard bar of known hardness and then through the indenter into the workpiece. The indentations in both the standard bar and the workpiece are measured and from the ratio of the diameters the HBN is derived. The loss in accuracy is made up for by the exceUent portabUity. 

The latest portable Brinell testers are spring-loaded, hand-held, and digitized to read direcdy in Brinell hardness units. Their accuracy is questionable because of extreme surface sensitivity and they are not in fact Brinell testers but RockweU indenters caUbrated to read in Brinell numbers. 

Portable hand-held direct reading Rockwell testers have been developed and are in use, as are numerous C clamp configurations, all intended for field or shop use. The newest computerized digital readout Rockwell tester provides the ultimate in portabiUty at the cost of some loss of sensitivity due to the very light loads used. 

Barcol Indenter. The Barcol hardness tester is a hand-held, spring-loaded instmment with a steel indenter developed for use on hard plastics and soft metals (ASTM D2583) (2). In use the indenter is forced into the sample surface and a hardness number is read direcdy off the integral dial indicator caUbrated on a 0 to 100 scale. Barcol hardness numbers do not relate to nor can they be converted to other hardness scales. The Barcol instmment is caUbrated at each use by indenting an aluminum ahoy standard disk suppHed with it. The Barcol test is relatively insensitive to surface condition but may be affected by test sample size and thickness. 

Operator skih and experience are necessary to obtain consistent results usiag a Durometer. Speed of load appHcation, dweh time, and sample thickness can affect reproducibhity of results. Durometer cahbration prior to each test series is done usiag a test block provided with the iastmment. When large numbers of tests are required, improved consistency of results are obtained if the Durometer is used with the accessory vertical stand rather than hand held. 

Wire sparklers are wires coated with pyrotechnic composition which are hand-held and produce a gende spray of gold sparks from iron filings. Fountains are cardboard tubes filled with chemical mixtures that produce a spray of color and sparks extending 2—5 m into the air. Roman candles are cylindrical tubes which repeatedly fire colored stars distances of 5—20 m into the air. These items typically contain 5—12 stars. 

Sohd tantalum capacitors have a high volumetric capacitance which makes them attractive for use in miniaturized electronic systems like cellular telephones, hand-held video cameras, and personal computers. The insensitivity of their capacitance to temperature and their abiUty to operate at temperature extremes explains why these devices are used in such harsh environments as automobile engine compartments. Sohd tantalum capacitors are extremely rehable and, therefore, are often the capacitor of choice in critical appHcations like spacecraft electronics, pacemakers, and safety equipment. 

The hand-apphed shroud of shrinkable PE usually consists of a premade bag large enough to envelop the load. Equipment to shrink the wrap ranges from small propane-fired hand-held units, which take... 

Specification for elecirosiaiic hand held spraying equipment for non flammable material for painting and finishing BS EN 50059/1991 ... 

Use of propellants, e.g. hand-held aerosol cans Electrolytic processes... 

METROSOFT Metrosonics Rob Brauch P.O. Box 2307S Rochester, NY 14692 (716) 334-7300 Industrial hygiene information record system. Utilizes hand held monitoring system to record exposure data on computer. 

LVHV nozzles require very careful design. They can be effective in capturing and removing dust from operations that are otherwise difficult to control, e.g., hand-held tools and some fixed-machine grinding and other operations. Installation costs for LVHV systems can be considerably higher than for conventional local exhaust systems. However, operating costs can be lower be-... 

Research has been conducted to evaluate the effectiveness of several LVHV nozzle configurations for capturing tracer aerosols for simulated industrial operations.Studies have been conducted to evaluate dust capture for LVHV nozzles on hand-held tools, and have demonstrated over 90% collection efficiencies for operations such as grinding and sanding. 

Umiglily falwitareil nr>//ic for a hand-held cup-wheel grinder... 

FIGURE 10.27 Examples of LVHV exhaust nozzles for dust control on hand-held tools. ... 

Commercial products do exist that integrate shrouded and ventilated grinding wheels and other hand-held tools. It may be possible to find an existing LVHV-type product that will work well for some applications, requiring only to be connected to an appropriate air handling system. However, it is also sometimes necessary to make custom-fabricated LVHV nozzles for some hand-held tools and for essentially all fixed-machine dust-generating tools. I he best approach is to consider the following ... 

Kennedy describes a method using an ultrasonic nebulizer to generate a fog of water droplets w hich is used in the same way as smoke to visualize airflows. Several types of nebulizers are available but they require an electrical connection and are not hand-held. Food dye can be added to the water to produce colored fog. The nebulizers are expensive (about 1500 ECU) but have negligible operating costs. Although the amount of smoke produced is small, it is nontoxic and nonirritating. 

Two other principles that have been made commercially available are (11 rhe reaction between pyrosulfuric acid (H2S2O7) and water (water vapor in air) to form sulfuric acid aerosol and (2) rhe reaction between ritaiJium tetrachloride (TiCl4) and water to form titanium dioxide (TiO,) and hydrogen chloride il Id), higure 12.5 shows two different hand-held, disposable smoke emitters. 

Electrical manometers have developed during the last 30 years. Modern electrical manometers are well suited for ventilation applications, both in the laboratory and in the field. The advantage of this type of instrument is fhat they are sensitive enough to measure small pressure differences with electrical output, enabling monitoring. A convenient feature, especially in the field is that the instrument is hand-held and there is no need for leveling on a bench, as for fluid manometers. The conversion of the pressure difference into an electrical signal can be based on several different phenomena. 

The vortex exhaust has a geometry that generates a rotating flow behind the opening. It is suitable for installation in a narrow space and it is traditionally used with hand-held equipment producing jets of air and particles. This type of exhaust opening is also called a tornado exhaust or a cyclone exhaust. 

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