Metritape Level Sensor Working Principle


Whether your application is an individual tank, a tank farm, a reservoir, or a river, our unique Metritape level sensor provides a reliable solution. This is because resistance-tape is remarkably different from other level sensors; in principle, appearance, and performance.

Metritape Level Sensor Working Principle

The reason for Metritape’s success is its simple principle of operation and the high quality materials used in its construction. The sensor consists of a gold plated, stainless steel base strip, partially insulated from a gold plated wire that is wound around the base strip to form a helix (figure 1).

This helix is sheathed in either Mylar or HastelloyTM to insulate the sensor’s inner elements from the liquid to be measured. Sliding the sheathed helix into a protective channel that leaves the front of the sensor exposed then completes the sensor. The sensor is generally contained within a still pipe suspended from the top of the tank. However, other mounting options are available.

When the sensor is installed (figure 2), the outer envelope jacket (1) is compressed by the hydrostatic pressure of the liquid (2). This causes the gold wire winding to contact the gold plated base strip. The resulting change in the resistance of the gold wire (3) indicates the length of active helix and the distance from sensor top to liquid surface.

The helix is wound at 4 turns per inch, 1000 ohms per meter (305 ohms per foot) resistance gradient providing ¼ inch resolution. Metritape sensors are easily installed from tank top by dispensing the flexible sensor from its cardboard shipping reel into a customer supplied still pipe of PVC or Steel.

Metritape Simply Works

With more than 25,000 Metritape sensors installed worldwide, this simple, rugged technology is selected because of its many features and benefits:

  • No moving parts; nothing to wear out
  • High reliability; virtually maintenance free
  • Easy to install from tank-top; no need to empty tank
  • Not adversely affected by agitation, foam, vapors, or product build up
  • Calibration remains stable and drift free
  • Intrinsically safe for use in flammable liquids
  • Temperature detectors can be added to sensor


Metritape is the solution for a wide range of level gauging applications, including:

  • Inventory Control
  • Distributed Data Collection and Telemetry
  • Process Tank Monitoring
  • Hydrology and Flood Control