Liquid-level gauges

Figure 3.2. Liquid-level gauge for an ammonia tank.

Provide reliable seal liquid makeup, using liquid level gauging and monitoring wth recording to ensure good records of performance. The liquid level must be maintained otherwise, the hazards of a bleedthrough or backflow can become serious. 

Still-gauging methods are adequate for only the largest leaks. The accuracy of most tank-installed liquid level gauges is usually /s in. at best. A product loss reflected by a 0.062-in. level drop for a 100-ft-diameter tank translates to a 306 gal/day leak. If this Vi6-in. drop in product level is not discernible from the masking effects of fluid expansion, losses in excess of 2650 barrels annually will go undetected. At, for example, 20 per barrel, this loss amounts to over 53,000 for a single tank. Most importantly, the associated liability risks of groundwater contamination could involve much greater potential costs. 

Are containers equipped with an approved liquid level gauging device (except those filled by weight) ... 

Are containers fitted with a fixed tube liquid level gauge at 85% of water capacity ... 

Are all storage tanks fitted with liquid level gauges ... 

Are liquid level gauges adequately protected from physical damage ... 

At least weekly, the liquid level gauges of low-pressure containers should be observed. If, at any time, a container shows a loss of more than 10%, it should be refilled, unless the minimum gas requirements are still provided. 

Australia SAAAS1271 Safety valves, other valves, liquid level gauges and other fittings for boilers and unfired pressure vessels... 

Use Radiation therapy (cancer), radiographic testing of welds and castings, as a source of ions in gas-discharge devices, as the radiation source in liquid-level gauges, for locating buried telephone and electrical conduits, portable radiation units, y-irradiation for wheat and potatoes, as a research aid in studying the permeability of porous media to flow... 

Connections to containers, except safety relief connections, liquid level gauging devices, and plugged openings, shall have shutoff valves located as close to the container as practicable. 

Power was supplied from a dc generator located externally to the area. Temperatures were measured with a Rubicon potentiometer with a range of 0.01 to 100,000 jlv in conjunction with a Leeds and Northrup galvanometer. Pressure was controlled in the dewar with automatic pressure control valves and was measured with a 12-in. laboratory test pressure gauge. Liquid level was indicated with a resistor-type liquid level gauge. 

For a 5.0-m-i.d. liquid oxygen storage vessel (horizontal cylindrical vessel), the indication on a differential pressure level gauge is 19 kPa. If the fluid in the vessel is under a pressure of 101.3 kPa, determine the liquid level and the sensitivity of the liquid level gauge. 

A capacitance liquid level gauge is used to indicate liquid level in a liquid oxygen storage vessel. The total length of the probe is 2.0m.and the inner and outer cylinders have diameters of 50 and 75 mm, respectively. If the capacitance reading of the probe is 400 ppF,... 

Wifli LNG, flie boU-ofif vapour is usually returned or collected via a vapour return line. If flie tank or vessel is over-filled when topping-out, due, say, to malfunction of the high liquid-level gauge, then liquid will pass into the warm return line, where it wiU evaporate and create an overpressure problem. 

Ordinarily, liquid level in the lower barrel is controlled by torque tube level controls and diaphragm-t3 e valves. Connections for liquid level gauges, pressure gauges, and drains are provided. 

FIG. V-33 Process vaporizer with controls factory mounted. Note float and float-operated valve, liquid level gauge, thermostatic steam valve, condensate traps, bursting disc relief valves, and miscellaneous hand valves, including bypasses and strainers. (Source Armstrong Engineering Associates.)... 

ASME B31.3, Process Piping, American Society of Mechanical Engineers, 2002. AS 1271, Safety Valves, Other Valves, Liquid Level Gauges and Other Fittings for Boiler and Unfired Pressure Vessels, Australian Standard, 1997. 

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