Level instruments locations

Gauge glass and level instruments to be located at inlet-outlet end. 

Sizing of the blowdown drum and location of the level instruments are based on the following guidelines. The reader should refer to Figure 2 while reviewing the following items. 

Demonstration of surface shifts in the nonmetal levels, i.e. in the C Is and N Is levels, was not feasible in these first efforts. These levels are located considerably deeper in energy and were inaccessible. Recent developments in synchroton radiation instrumentation,15 however, allow high resolution core level studies to be performed involving these levels.16-20 The first such study was carried out on the (100) and (111) surfaces of VC16 and a surface shifted C Is level was clearly observed (Figure 25.2). A C Is... 

Third, safety valve leakage is indirectly monitored from the safety grade pressurizer pressure and level instrumentation system also located in the control room. 

Cold reference leg" water level instruments measure reactor vessel water level by measuring the differential pressure of two columns of water — the variable leg and the reference leg. The reference leg is maintained filled to a constant height of water by a condensate chamber located at the top of the reference leg. Non-condensible gases can collect in the condensate chamber and can become dissolved in the water at the top of the reference leg. These dissolved gases can be transported down the reference leg by small leaks in valves and fittings at the bottom of the reference leg. 

The preferred location for level instruments is away from the turbulence at the liquid outlet nozzle. Although the vessel is provided with a vortex breaker, instruments should be set in the quiet zone of the vessel for example, on the opposite side of the weir or baffle or near the vapor outlet end. Process nozzles should be located a minimum from the tangent line. Steam-out conneaions should be located at the end opposite the maintenance access and vent in the bot-... 

To facilitate specific elevation requirements for level instruments or positioning a maintenance access, nozzles may be located off the main axis. These nozzles are generally referred to as hillside nozzles. A typical hillside nozzle is shown in Exhibit 5-15- Tall vertical drum nozzles should be elevated and oriented using the tower subjea as a guide. It should be noted, however, that nozzle locations are not restricted by internal components, as is die case for the distillation tower. More information on vertical drums is available in Chapter 10, Towers. 

Level instruments are located in the liquid section of the tower, usually at the bottom. The elevation of the nozzles is dictated by the amount of liquid being controlled or measured and by standard controller and gauge glass lengths. This information is furnished on the instrument vessel sketch. Exhibit 10-35 illustrates level instrument requirements. 

Level controllers, switdies, and gauges are either located individually or grouped on a common bridle or standpipe. The controller must be operable from grade or a platform gauges and switches may be operable from a ladder if no platform is available. Exhibit 10-59 illustrates arrangements for level instruments. 

If tank heaters are employed, mobile maintenance equipment should be located in the mo.st convenient area. Tank maintenance includes. such aaivicies as internal inspection, cleaning, and repairs to internals, roof suppoas, and level instruments. Setting entrances to stairway or ladder areas at grade is the mast convenient choice for operations personnel. It should be noted that. stairways are not recommended for tanks whose diameters are le.s.s than 15 ft 6 in (4.7 m). 

For. safer, handrails. should be added along the tank roof edge on both sides of the ladder or stairway. Level instruments with internal floats are u.sually located in this area, as are roof maintenance access openings, which are convenient for in.speaions. repairs, and cleaning of instruments. 

The distorting influence of the physical horizon line on measurement of astronomical azimuths can be levelled by locating the instrument on the beach, whose calm surface coincides with the astronomical... 

A Q-switched, frequency-quadrupled Nd—YAG laser (X, = 266 nm) and its accompanying optical components produce and focus the laser pulse onto the sample surface. The typical laser spot size in this instrument is approximately 2 pm. A He-Ne pilot laser, coaxial with the UV laser, enables the desired area to be located. A calibrated photodiode for the measurement of laser energy levels is also present... 

When groundwater contaminant plumes are suspected of having significant depth as well as lateral distribution, a three-dimensional array of monitoring points is needed to identify and characterize such plumes. Thus, groundwater data must be obtained from a number of different locations and from a number of different depths at each location. As a result, either a large number of drillholes are required, each with separate instrumentation installed, or instruments must be combined and installed at multiple levels in each of a smaller number of drillholes. 

The sensitivity of the fluorescence methods varies considerably with the instrument used. Advances in modern instrumentation and the power of today s computers allow for a much improved sensitivity. Using commercially available instruments and modern computers equipped with appropriate software, detection limits down to 10 pg of calf thymus DNA can be achieved using ethidium bromide. (We have achieved such levels using several Perkin-Elmer MPF66 Instruments at various locations.)... 

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