Types of Level Gauges

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Types of Level Gauges[edit]

Several forms of level gauges exist in the industry. Depending upon the types of liquids such as water, oil, diesel etc. measured by level gauges, they can be classified into following categories:

  1. Tank level gauges: These level sensing devices generally determine volume of liquid enclosed in the tank.
  2. Fuel level gauges: These devices mainly provide fuel level readings in case of automobiles and other equipments consuming fuel.
  3. Water level gauges: These level gauges are basically applied to determine the rise or fall occurring in water level.
  4. Mechanical level gauges: This category of level gauges is mainly employed in underground storage tank applications for measuring the level of liquid.

Some other kinds of level gauges are mentioned below:

Magnetic level gauges[edit]

“These types of level Gauges are used for highly hazardous/toxic liquids where gauge glasses are susceptible to attack by the process medium.”[1] Their maximum working temperature and pressure range can be 4000C and 220 bar respectively. Use of these devices is mainly recommended for combustible, risky and corrosive fluids. Besides, they are capable for inter-phase level detection. Liquids involving extreme temperature and pressure can also measured by these gauges. They can be installed in underground storage tanks also. These types of level sensors work upon two fundamental principles. One is the Archimedes Principle which states that any object submerged in a fluid tends to experience the same buoyant force as the weight of the liquid put out of place. The other principle is the phenomena of attraction and repulsion between opposite poles and poles of permanent magnets respectively.

Reflex Level Gauge[edit]

rent tube which is clamped to the gauge body. The sight glass has prismatic right angled grooves on the side facing the liquid and vapor space.”[2] Based upon the presence of liquid or vapor area, external light waves incoming towards the reflex level gauge will undergo either absorption or reflection. In case of vapors, the light radiations running into the groove surface are entirely reflected and returned back to the direction of observation. Thereby, the vapor area gives out silvery white appearance. On the other hand, the light radiations which come across the surface of the grooves in the liquid region are fully absorbed owing to which the liquid at the back of the glass emerges black in color.

-- 02:41, 19 April 2018 (EDT)=== Transparent Level GaugeTransparent level indicators are highly useful in chemical industries and petrochemical fertilizers. As the fluid is stored in high pressure and high temperature, the transparent level indicator is very useful to find the fluid level. Transparent Level Gauge WORKING PRINCIPLE Apart from glass tube level gauges, transparent level gauges are always fitted with two plate transparent glasses between which the fluid is contained. The fluid level is indicated as the result of the different transparency of the two media and in some cases (for water steam), by conveying upwards on to the surface of separation (between liquid and gaseous substances) a source of light located at the back of the gauge, the rays of which are totally reflected down to the observer.

APPLICATIONS Transparent level gauges are suitable for almost all installations. In fact they permit:

the use of mica shields or Polytrifluorochloroethylene shields to protect the glass from the corrosive action of the process fluid the observation of interface the observation of the liquid colour This instrument consists of a metal body, machined to have an internal chamber and one or more front windows (on each side of the gauge). On each window a special high resistance plate transparent glass is applied with sealing joint and metal cover plate hold by bolts and nuts.

The chamber is connected to vessel with cross fittings and flanged, threaded or welded ends. Usually, between the instrument and its connecting ends, valves are fitted to consent shut-off piping and to disassemble the level gauge without to empty the vessel. Drain valves can also be fitted to cross fittings device.

To avoid leakage in case of glass breakage, safety ball-check device can be provided in cross-fittings or shut-off valves. This kind of indicator is suitable for water/steam. To protect glass surfaces from corrosive action of the process fluid, Transparent Level Gauges can be fitted with Mica shields or Polytrifluorochloroethilene shields. This kind of indicator is suitable for liquids colorless and very fluid.

Level Gauge In some case (i.e. for water / steam) the best reading is obtained by conveying upwards on the surface of separation (liquid/steam or vapor interface), a source of light, located on the back of the gauge, the rays of which are totally reflected down to the observer.

Bi - Color Level Gauge[edit]

These devices are considered appropriate for measurement of level in boilers since the glasses used in their construction are carefully guarded against the wet steam generated in a boiler drum. This steam protection is provided by putting in high quality mica sheets. Detection of level in bi-color level gauges depends upon the distinction in index of refraction between steam and water. They can work with temperatures as high as 120kg/cm2 and well suited for saturated steam applications. kdtgk,cgtkcgtydi
“Bi-colour gauge is in fact a transparent gauge with its liquid chamber in a wedge shape section and fitted on a rear side with an illuminator.”[3] Two color filters, one red in color and the other green in color are positioned directly facing the light source in the illuminator, hence the name bi-color gauge. In cases where red color light radiations hit upon the water, they gets averted in one side and then absorbed whereas when they encounter the steam region, they tends to pass through without any constrictions and emerges red in color. On the other hand, reverse action takes place for light radiations passing via green filters.

Tubular Level Gauge[edit]

These types of level gauges detect the level of liquid in the process vessel via direct communication means. These devices mainly find their application in low pressure, non-toxic and non-sticky liquid level measurement applications.

See Also[edit]

Level Gauges



Liquid Level