Density gauges

Radiation-Density Gauges Gamma radiation may be used to measure the density of material inside a pipe or process vessel. The equipment is basically the same as for level measurement, except that here the pipe or vessel must be filled over the effective, irradiated sample volume. The source is mounted on one side of the pipe or vessel and the detector on the other side with appropriate safety radiation shielding surrounding the installation. Cesium 137 is used as the radi-... 

Density Gauges These are used to measure the density or suspended solids content of the feed and underflow streams. Gamma radiation devices are the most commonly used for automatic control, but ultrasonic devices are effective in the lower range of slurry density. Marcy pulp density scales are an effective manually operated device. A solids mass flow indication is usually obtained by combining a density gauge output with the output from a flowmeter. 

Loss of a radioactive soil density gauge or well logging gauge. 

Density gauges based on the absorption of gamma radiation are used wherever the automatic determination and control of the density of liquids, solids, or slurries is important. The oil industry relies heavily on such instmments. Other applications are in the handling of slurries in mineral processing or even in the food industry. One of the earliest users of radioisotope instmments was the tobacco industry, where density gauges make sure the right amount of tobacco is packed into each cigarette. 

Density Nuclear gauges are the norm for density measurement. Nuclear density instruments require nuclear handling permits in most countries. Note that there are now some types that use very low level sources that do not require nuclear licensing. Density gauges should be recalibrated regularly as they are subject to drifting. Small flow applications may be able to use a coriolis meter to measure both mass and percent solids with one instrument. 

One such is Venera 4, launched on June 12, 1967. It reached the planet on October 18 and dropped an instrument package containing two thermometers, a barometer, a radio altimeter, an atmospheric density gauge, 11 gas analyzers, and two radio transmitters. Data collected by these instruments were transmitted to the space vehicle "bus parked in orbit around the planet and then sent on back to Earth. After completing the transmission, the bus deployed a parachute to reduce its speed. It then descended into the Venusian atmosphere to an altitude of 15.51 miles (24.96 km), at which point communications were lost. 

Let us consider a somewhat unusual application of this type of instrument. In the manufacture of titanium it is important to keep liquid TiC at a particular high temperature and pressure in a vessel. TiC has a triple point (i.e. the pressure and temperature conditions at which all three phases - solid, liquid, and vapor - of a substance are at equilibrium) in the neighborhood of the particular technical conditions. By using a y-density gauge it is possible to detect when the triple point is exceeded because of the disappearance of the vapor-liquid interface. This allows a simple method of control of the process conditions in the vessel. 

On-Line Instrumentation Used in the Coal Preparation Industry. Ash monitors, nuclear density gauges, and pH monitors are the only on-line instruments currently used to measure process or material parameters in U.S. coal preparation plants. 

Nuclear density gauges are typically used as process control instruments to monitor the density of water-magnetite slurries used in the heavy medium cleaning circuits The instrument... 

The development status of process control instrumentation lags that of the quality control instruments significantly Nuclear density gauges function in the coal preparation plant environment The slurry concentration meter has application in the intermediate and fine sized coal cleaning circuits and needs to be tested in a preparation plant Other devices, such as ash monitors to control the operation of heavy media baths or jigs are not available and instruments developed for other process industries are not suitable for use in coal preparation plants Modeling studies of the various unit operations are required in order to ascertain the fundamental parameters required to automate the control of these systems Primary process control instrument needs include ash, sulfur, and moisture monitors secondary needs include an on-line washability and ash fusion measurement ... 

Depleted uranium (shielding, ballast, etc.) Moisture density gauge Static eliminator Tritium exit sign Pu pacemaker Minimal Significant health effects impossible from radiation exposure... 

Interpret... the results of a sand cone and nuclear density gauge field density tests. (4)... 

First, the moisture and compaction level of the stabilised soil using novel binder was measured using a nuclear density gauge. Table 46 shows the in-situ density and moisture content at four different points of the trial pavement. 

Weimer AW, Gyure DC, Clough DE. Application of a gamma-radiation density gauge for determining hydrodynamic properties of fluidized beds. Powder Technol 44 179-194, 1985. 

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