Metritape Operation 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.

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 Hastelloy^TM  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

Applications

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

Water and Wastewater

The Metritape level sensor is ideal for ponds, streams, tanks or sumps because of its high resolution, stable output and simple pipe mount installation. Since it has no moving parts and because specific gravity and viscosity do not adversely affect its output, Metritape is perfect for gauging raw sewage and sludge. Hundreds of municipalities and treatment plants use this reliable sensor in diverse applications including cooling ponds, digesters, groundwater, reservoirs, raw sewage, sludge pits, and wet wells.

Slurries and Viscous Liquids

Metritape has proven durability in the gauging of slurries and dense liquids. The sensor's smooth, non-mechanical design resists buildup and is unaffected by agitation. Heavy ores, syrups, viscous muds and high viscosity oils do not hamper its operation. Applications include coal slurries, drilling mud, iron ore slurries, lime slurries and pulp and paper.

Petroleum

The Metritape sensor's outer sheath gives it a smooth, nonstick surface ideal for gauging waxy crudes and heavy oils. Its chemically inert surface is also ideal for gauging refined products. Up to three temperature detectors can be built into the Level / Temp model which carries full intrinsic safety approvals. Applications include avgas, bunker C, crude, diesel oil, fuel oil, gasoline, jet fuel and naptha.

Chemicals

Organics, inorganics, solvents, toxic substances and chemical waste tanks have all been successfully gauged with resistance-tape level sensors. Applications include acetic acid, acetone, benzene, caustics, chromate, condensate, methanol, phenol, plating solutions, sulfuric acid, toluene and xylene.

Metritape Product Selection

The Metritape product line includes Aquatape for water and wastewater, Petrotape for petroleum and fuel and Chemtape for chemicals and petrochemicals. The Metritape family also includes the LA sensor series for higher temperatures and pressures. Please consult the product selection chart to determine which Metritape sensor is right for your application.

Additional information about each product can be obtained by clicking within the text of the sensor selection chart or by downloading the individual product data sheets, which are best viewed with Adobe Acrobat Reader.