Float & Tape Gauges

2500 (ATG)

Mechanical reliability with always-visible level indication.

What It Is & How It Works

A float and tape level gauge uses a buoyant stainless-steel float riding directly on the liquid surface, connected by a perforated tape to a precision counter mechanism at the tank roof or ground level. As the liquid rises or falls, the float moves the tape, rotating a drum and producing a continuous mechanical level reading without external power.

The measurement is driven entirely by buoyancy and gravity. The float tracks the surface, the tape transmits that motion, and the counter displays level in feet, inches, and fractions. Because there is no electrical signal in the measurement path, the gauge holds its reading through power outages, lightning, and harsh process conditions, making it the standard for visible, fail-safe level indication.

Installation involves mounting the gauge head on a tank nozzle and running the float assembly vertically through the product. Guide wires, stilling pipes, or pan floats maintain stable operation in turbulent tanks or those with internal obstructions. Fixed-roof, floating-roof, cone-roof, and pressurized configurations are all supported.

Accuracy reaches ±1/16 inch over the full measurement range. Modular cartridge assemblies simplify field maintenance. For facilities requiring remote monitoring, a digital transmitter mounts directly to the gauge head, converting float motion into 4–20 mA, HART, or Modbus output while preserving the local mechanical readout.

Float & Tape vs. Radar Level Gauges

Float and tape gauges provide a direct mechanical reference to the liquid surface, always visible without power. Radar gauges calculate level electronically via microwave signal, with no moving parts. Many terminal operators use both: radar as the primary electronic gauge, float and tape as the mechanical verification that remains readable during power loss or system failure.

Choose radar for non-contact, low-maintenance electronic measurement.

Choose float and tape for mechanical reliability, local visibility, and power-independent operation.

When to Choose a Float & Tape Gauge

Float and tape gauges are selected when visible mechanical indication, power-independent operation, and long-term reliability drive the decision:

Petroleum Terminals & Refineries: Inventory measurement for product storage and blending where a visible mechanical reference complements electronic gauging.
Chemical & Petrochemical Storage: Corrosion-resistant materials handle aggressive products where a simple, reliable gauge reduces maintenance burden.
Water & Wastewater Treatment: Level indication for reservoirs and process tanks where mechanical simplicity and low operating cost are priorities.
Dual-Measurement & Redundancy Applications: Independent mechanical verification alongside radar or servo primary gauges, supporting API 2350 and OIML R85 dual-measurement principles.
Retrofit & Brownfield Installations: Direct replacement into existing tank nozzles and fittings, with optional transmitter upgrade for digital output.

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2500 (ATG) 2520 (ATG)

Why It Excels

Power Loss, Lightning, or System Failure

Purely mechanical operation maintains a readable level indication when electronic systems are offline.

Facilities Requiring Visible Level Confirmation at the Tank

Operators read the level directly from the counter without instruments, radios, or control room access.

Long-Range Tanks with Minimal Maintenance Budget

Simple tape-and-drum mechanism with modular cartridge design extends service life and simplifies field repair.

Tanks Requiring Independent Mechanical Verification

Provides a technology-diverse second measurement for custody-transfer audits under API 2350 and OIML frameworks.

Hybrid Mechanical-Electronic Monitoring

Adding a transmitter creates a dual-output system, retaining mechanical indication while feeding digital data to SCADA or FuelsManager®.

What to Consider Alongside Automatic Tank Gauges

Consider an alternative when:

You need density, interface, or BS&W measurement from the primary gauge. See Servo Level Gauges.
The application requires non-contact, maintenance-free electronic measurement. See Radar Level Gauges.
Tanks are small, underground, or require flexible probe installation. See Magnetostrictive Level Gauges.
You need only point-level alarms, not continuous measurement. See Level Alarms.

How Float and Tape Gauges fit into a larger system

Pair with Radar or Servo Level Gauges for dual-measurement verification. Custody-transfer standards (OIML R85, API MPMS) emphasize independent verification. Float and tape gauges provide the mechanical reference; radar or servo delivers the electronic primary. See Radar Level Gauges or Servo Level Gauges.
Pair with L&J MCG 1090/1095 Level Alarm Probes for overfill protection. Independent high-level alarms create an API 2350-compliant safety layer separate from continuous measurement. See Level Alarms.
Add a transmitter and pair with Varec FuelsManager® for inventory intelligence. A float and tape transmitter converts float motion into digital output, feeding software like FuelsManager for real-time volume correction, tank strapping, and automated compliance. See Float & Tape Transmitters and FuelsManager®.

Featured Products

Varec 2500 — Automatic Tank Gauge

The industry-standard float and tape gauge with over 90 years of field history. Designed for general bulk storage across petroleum, chemical, and water applications with a range of float and tape configurations for different tank types and products. Pair with a Varec 2920 FTT or L&J MCG 2000MAX transmitter for hybrid mechanical-digital operation.

Varec 2520 — High-Pressure Automatic Tank Gauge

Float & tape gauge engineered for pressurized bulk storage applications. Rated for higher-pressure service where standard ATGs cannot be used, while maintaining the same mechanical reliability and local indication.