Showing posts with label direct level. Show all posts
Showing posts with label direct level. Show all posts

Monday, December 14, 2015

Process Measurement - Tank Fluid Level Measurement

industrial magnetic level indicator
Industrial Magnetic Tank Level Indicator
Courtesy Granzow
Industrial process control often requires the storage of liquid in vessels or tanks. Continuous and accurate indication of the liquid level within the tank is an essential data point for safety and process control. There are a number of methods and instrument types utilized to provide tank level measurement, each with attributes that may be advantageous for a particular installation. Some of the selection criteria for a tank fluid level indicator may include:
  • Direct or indirect measurement of level
  • Tank shape, regular or irregular
  • Media compatibility with measurement device
  • Requirements for maintenance or calibration
  • Compatibility with process temperature and pressure range
  • Local display and visibility
  • Level indication signal type and transmission
  • Level alarm switches or other indicators
When the instrument of choice is a magnetic level indicator, also referred to as a magnetic level gauge, the selection has usually hinged upon one of this instrument's strengths. Its use for providing level indication has a number of positive attributes:
  • Continuous level measurement
  • Operable without electric power
  • Direct visual tank fluid level indication, regardless of tank shape or profile.
  • Wide range of operating temperature and pressure
  • Breakage resistant construction
  • Range of construction materials available to accommodate corrosive media
  • Measuring indicators, switches, and transmitters mounted externally, without contacting the medium being measured.
  • Low maintenance operation.
  • Readable level indication from greater distance than glass sight gauges.
  • Applicable to large fluid level ranges with a single instrument.
These process measurement devices have a strong position in the tank level measurement field and should be considered as a candidate for fulfilling those application requirements. I have included a technical data sheet from Granzow, one of several manufacturers of this type of instrument, so you can see more detail. Share your application challenges with a sales engineer that specializes in level measurement. Combining your process knowledge with their product application expertise will yield positive solutions.

Wednesday, August 20, 2014

Level Measurement

level measurement
Level Indicator
(King-Gage)
Level measurement is an important process measurement. In many processes, it is important to measure the level of various liquid and solid materials. Effective level measurement provides reliable and continuous operations by maintaining optimum material inventory, by maximizing plant availability, and the prevention of spillages and other process disturbances.

Level is measured at the interface between two material "phases", that is, between liquid and air or solid and air, or other different density materials. The different phases must be clearly separated. When liquids are thoroughly mixed together, level cannot be measured because there is no separation of phases. The interface must be definite in nature.

In the case of an open tank filled with water, the point at which water and air contact is the definite interface, or phase change. Another interface example would be between oil and water. In this example, the specific gravity of oil is less than water, so oil floats on top, but in separate form. Liquids that mix well together do not have a clear interface, so it is difficult to determine level of each.