Level indicator

Magnetic fluids Magnetic flux leakagf Magnetic inductions Magnetic level indicator Magnetic materials... 

The four process control parameters are temperature, pressure, flow, and level. Modem process level detection systems are varied and ubiquitous in modem chemical plants there are thousands of processes requiring Hquid level indication and Hquid level control. From accumulators to wet wells, the need for level devices is based on the need for plant efficiency, safety, quaUty control, and data logging. Unfortunately, no single level measurement technology works rehably on all chemical plant appHcations. This fact has spawned a broad selection of level indication and control device technologies, each of which operates successfully on specific appHcations. 

Level devices can be divided into two broad groups those that indicate level and those that provide means to control level. Indication devices report where the level is at any given point in the process. Control devices provide supervision of the process and can be used to initiate other devices to control process levels. 

Dip Stick Indicators. Visual level indication can be obtained by dropping a weighted cable or rigid dip stick into the media until it reaches the bottom of the vessel. Graduations are marked on the cable or stick. Upon retrieval the operator looks for the point of dry vs wet indicating the depth of the media. This method of level indication is useful in ambient/atmospheric appHcations in nonha2ardous environments. It is not recommended for other appHcations. Measurements are accurate only to the extent of the skill of the operator. 

Impurities above maximum levels indicated in pubUshed specifications (42) can affect the properties of the finished casting. SUicon, for example, is normally added to many of the copper—beryUium casting aUoys to promote fluidity, but excess sUicon reduces ductUity. Excessive zinc, tin, phosphoms. 

Fig. 1. Fat sphtter. TRC, temperature recorder controller FLIC, Hquid level indicator controller PCV, pressure control valve and HCV, heat control valve.

Nitrogen blow Provide level indicator in feed vessel with through into alarm/interlock drum from feed vessel during pressure transfer leading to loss of containment. AGA XK0775 CCPS G-3 CCPS G-15 CCPS G-22 CCPS G-23 CCPS G-29 FMEC 1997... 

Oil level indicator Vent liberated gases in the breaker Oil filling vent... 

At the time of the solvent methanol experiments a metering pump was used. In some experiments the pulsating action of the pump can be disturbing, so a high-pressure syringe-type pump can be used. Since mass flow controllers are available now, the combination of a gas-pressurized feed tank on an electronic scale for liquid level indication and a mass flow controller seems to be a good choice. Both the feed tank and separator can be heated or cooled. In the case of the solvent methanol experiments. 

Balance machines are limited to the 25 to 50 pin sensitivity level, indicating that Equation 9.3 for the example will take the balance close to the limit. 

Allylic and benzylic radicals are also stabilized by both acceptor and donor substituents. As shown in Table 12.5, theoretical calculations at the MP2 level indicate that substituents at the 2-position are only slightly less elfective than 1-substituents in the... 

The rate constants reported in Table 4 are double the specific rate constant for a given site when two identical sites are present, so that the actual position reactivity is half of the level indicated. Since the rates are reported as seeond order, the... 

Fig. 11. Simulated diffraction space of a chiral (40, 5) SWCNT. (a) Normal incidence diffraction pattern with 2mm symmetry (b),(c),(d) and (e) four sections of diffraction space at the levels indicated by arrows. Note the absence of azimuthal dependence of the intensity. The radii of the dark circles are given by the zeros of the sums of Bessel functions [17].

On more than one occasion, tanks have overflowed because the contents were replaced by a liquid of lower specific gravity. The operators did not realize that the level indicator measured weight, not volume. For example, at one plant a tank that had contained gasoline (specific gravity 0.81) was used for storing pentane (specific gravity 0.69). The tank overflowed when the level indicator said it was only 85% full. The level indicator was a DP cell, which measures weight. 

If the level indicator measures weight, it is good practice to fit a high-level alarm, which measures volume. 

If you use ball-float level indicators, compare the size of the balls with those of the branches on the top of the vessel. If a loose ball could lodge in one of the branches, protect the branch with a metal cage, or use another type of level indicator. 

The probable cause of the accident was overfilling due to level indicator failure. Water removal from carbon dioxide was not always sufficient to assure good pressure and level readings in the tanks. Residual water could cause meters to fail from ice formation. 

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