Float-Type Level Indicator

Guide tube shall be removable from tank. Clean the tube regularly. 

Consider small diversion of incoming flow to the tube also for self-cleaning of the tube and drain holes at bottom. 

Provide reference nozzle at top. Measure empty space from the reference nozzle by a dipstick in case of urgency. Take care to wash the dipstick if acid level is checked. 

Material of Constmction of Float shall be corrosion-resistant Stainless Steel 316 or carbon steel coated with Teflon or glazed ceramic. 

Use strong multistrand wire (made of corrosion-resistant material) for connecting to the float. 

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Formation of emulsions that can confound interface level measurements Leak in float type level indicators... 

Fig. 8-20. HRE-2 float-type level indicator (covers a 5-in. range at psi-2000 operating pressure).

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 middle gauge cock is located at the boiler NOWL. Boilers operating at more than 250 psig have either two gauges or one gauge and an electric or electronic level indicator. Low water alarms are either float types or weight types. 

Plasticizer level indicators are essential to protect storage tanks from overflows. Differential pressure gauges and floating type indicators are used for the measurement of tank levels. It is possible to calibrate level gauges in volumetric units or to indicate depth of liquid. Level indicators can also have transmitters and these may be related to high level... 

Tank level measurement relies on nickel or Monel flush diaphragm d/p cells or nickel float-type indicators. Figure 11.48 shows both types. 

Liquid-level measurements. Instruments arc available for both on-off and continuous level measurements. On-off measurements are made with modified automotive-type spark plugs in which a long rod is used in place of the normal cent( r conductor of the spark plug. To olitain a continuous level measurement, the fluid head is measured with a differential pressure in.strumc iit. The pre.ssure reciuired to bubble a gas into the fluid is compared with the pressure above the liquid to obtain the fluid head. Resistance probe and float types of level indicators are available for use in liquid-metal. systems. 

Unusually difficult level-sensing problems are introduced when it is desired to measure or control the true level of a slurry or a boiling liquid. Most proven devices are density-sensitive, and the mean density of two-phase systems is usually unknown. Of the level transmitter types cited above, none appears adequate for continuous-range indication. For spot indication, float, capacitance, and Dynatrol transmitters are promising. 

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