Level instruments

Basically, the optical method uses equipment such as alignment telescopes, jig transits, and sight levels. Instruments with built-in optical micrometers for measuring displacements from a referenced line of sight enable an accurate determination of target movements, which are mounted on the machine. 

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. 

Instrumentation level instrumentation for MLO (standpipe level and ultrasonic) has limited use in a shutdown accident. Standpipe level is correct in the absence pressure m the system Ulirti sonic is correct only when the level is within the reactor coolant loops. 

The relatively low entry level instrumentation cost and the relatively simple experimental methods associated with GARField - both comparable to a standard bench-top relaxation analysis spectrometer as commonly used by the food industry, for example, for water/fat ratio determinations - offer potential advantages to the industrial based user. Indeed, the overwhelming majority of the applications development work described here has been carried out in collaboration with major multi-national industrial corporations such as ICI Paints, Unilever and Uniqema, with industry sponsored research laboratories and associations such as Traetek, and with a range of small-medium sized enterprises. 

The height of the liquid interface should be measured accurately when the liquid densities are close, when one component is present only in small quantities, or when the throughput is very small. A typical scheme for the automatic control of the interface, using a level instrument that can detect the position of the interface, is shown in Figure 10.40. Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation. 

By monitoring the 180.73 nm sulfur line, it was possible to detect 0.08 mg/1 sulfate with a precision of 0.8% relative standard deviation at the 200 mg/1 sulfate level. Instrument operating conditions are shown in Table 2.5. 

Good Laboratory Practice (GLP) The system provides a comprehensive feature set to aid customers in meeting GLP requirements. This includes features such as certificate-of-software validation, user-access levels, instrument and sequence logbooks, system-suitability software for aU supported HP instruments, standard GLP reports, and a GLP save option that encrypts and saves data and methods together. 

Cheremisinoff, N. P. Process Level Instrumentation and Control (New York Marcel Dekker, Inc., 1981). 

Given a level instrument, RELATE the associated fundamental principles, including possible failure modes, to that instrument. 

IDENTIFY the principle of operation of the following types of level instrumentation ... 

Given a basic block diagram of a differential pressure detector-type level instrument, STATE the purpose of the following blocks ... 

The different types of level instruments presented in this chapter are summarized below. 

In terms of limitations, the echo will be reduced if the vapor space is dusty or contains foam, water vapors, or mists. In addition, one should not use them to detect sound-absorbing (fluffy solids), sloping, or irregular surfaces. Therefore, the best guide for using ultrasonic level instruments is past experience on similar installations. 

Cylindrical vessels and horizontal tanks are used for the storage of fluids in the chemical process industries. Various level instruments are employed to determine the liquid level in process vessels. The exact liquid volume can be obtained either by calibration of the vessels or by tedious calculations. Partial volumes for horizontal, cylinders with flat, dished, elliptical, and hemispherical ends, and for vertical cylinders are employed for storing process fluids. 

Is the process liquid level maintained at the proper place Are liquid level instruments calibrated Are instrument leads plugged ... 

In aqueous systems, accumulation of a layer of oil or other low-specific-gravity organic liquid will cause a level instrument to indicate a level that is lower than actual. The oil may originate in... 

A misleading level indication due to oil accumulation in the column base caused severe operating problems in many aqueous services. In several cases, liquid level in amine towers rose above the bottom feed inlet and caused column flooding, while the level instrument indicated normal level (238). In another case (238), a glycol regenerator performed poorly when the liquid level in a kettle draw compartment rose above the overflow weir, while the level instrument indicated normal level (238). 

As with column bottom level, when an excessively high or low level can be hazardous, it is a good practice to install high-reliability level instrumentation including alarms, trips, and indicators, and to mount these as per Figs. 5.4 and 15.16. The trips usually switch off rotating machinery downstream of the accumulator and/or cut off product flow. 

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