Direct reading

The vacustat f (Fig. 11,23,2) is another useful gauge it covers the range 10 to 0 01 mm. of mercury and is usually employed in conjunction with an oil pump. It is direct reading, compact, and is charged with only about 8 ml. of mercury. The gauge must be swivelled to the vertical position when a reading of the pressure is required it does not automatically record a variable pressure. 

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. 

Ultrasonic Microhardness. A new microhardness test using ultrasonic vibrations has been developed and offers some advantages over conventional microhardness tests that rely on physical measurement of the remaining indentation size (6). The ultrasonic method uses the DPH diamond indenter under a constant load of 7.8 N (800 gf) or less. The hardness number is derived from a comparison of the natural frequency of the diamond indenter when free or loaded. Knowledge of the modulus of elasticity of the material under test and a smooth surface finish is required. The technique is fast and direct-reading, making it useful for production testing of similarly shaped parts. 

In this method. t Povver Factor meter is directly connected in the circuit ttnd a direct reading is obtained at any lottding. 

The instrument separates out and I. and provides a direct reading of I, and hence the condition of the arrester. Refer to Table 18.10 providing a brief procedure to monitor the condition of an arrester through such a monitor. 

Two separate flowmeter differentials should be read. These will probably have to be read with DP transmitter. It is suggested both DP units have one quality calibrated 6-in. gauge on transmitter output to directly read differential in %FS, FR, or psi. DP transmitters should be carefully bench-checked/calibrated, retaining indicated versus actual calibration data. 

Three different types of grating spectrometer detection sterns are used (Figure 3) sequential (slew-scan) monochromators, simultaneous direct-reading polychroma-... 

Direct-reading polychromators (Figure 3b) have a number of exit slits and photomultiplier tube detectors, which allows one to view emission from many lines simultaneously. More than 40 elements can be determined in less than one minute. The choice of emission lines in the polychromator must be made before the instrument is purchased. The polychromator can be used to monitor transient signals (if the appropriate electronics and software are available) because unlike slew-scan systems it can be set stably to the peak emission wavelength. Background emission cannot be measured simultaneously at a wavelength close to the line for each element of interest. For maximum speed and flexibility both a direct-reading polychromator and a slew-scan monochromator can be used to view emission from the plasma simultaneously. 

Attenuation of Provides short- or long-term TWA (e.g. up beta radiation to 8 hr, depending on model) of dust or Direct reading fume mass concentration. 

Sampling for Gases and Vapors Many gases and vapors can be sampled by deviees whieh indicate the eoncentration of the substance during sampling or shortly thereafter, without the necessity for chemical analysis. These direct reading devices are convenient and useful when properly calibrated. Other substances cannot be sampled by this method, because no appropriate instrument is available, and indirect methods which require laboratory analysis of the sample must therefore be used. Such analyses are often delayed by days or weeks, depending upon laboratory schedules. 

Direct reading samplers include simple devices such as colorimetric indicating tubes in which a color change indicates the presence of the contaminant in air passed through the tube, or instruments which are more or less specific for a particular substance. In the latter category are carbon monoxide indicators, combustible gas indicators (explosimeters) and mercury vapor meters, as well as a number of other instruments. 

The first (direct reading) method is fairly simple and results are available immediately. However, the instruments have limited sensitivity and must be recalibrated periodically. The second (absorption in a liquid or adsorption on a medium) and third (gas container) methods are generally considered more sensitive and more accurate method for trace analysis by gas chromatographs, infrared... 

Unlike many chemical hazards, radiological hazards can be easy to detect with highly sensitive, direct reading instruments. Radiological control personnel conduct surveys and post warning signs. 

An acceptable SSAHP will specifically address hazards of concerns, action levels, and protective measnres and techniqnes workers mnst nse. This will inclnde the nse of direct reading instrnments conpled with TWA-type sampling when warranted. 

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