What is the advantage of 50:1 turndown over standard orifice plate flowmeters?

A 50:1 turndown ratio means the TVA can accurately measure flow rates from 2% to 100% of maximum capacity. Standard orifice plates typically offer only 4:1 turndown, meaning significant low-flow steam consumption goes unmeasured. This results in incomplete energy data and potential billing or efficiency calculation errors.

Does the TVA require external pressure and temperature transmitters for saturated steam?

No. The TVA has in-built density compensation that automatically adjusts for pressure variations in saturated steam applications. For superheated steam measurement, additional ancillary equipment (pressure sensor) is required.

Can the TVA be installed in existing pipework with limited straight-run availability?

Yes. The TVA requires only 6 pipe diameters upstream and 3 downstream—significantly less than orifice plates (20D/7D) or vortex meters (15D/5D). This makes it suitable for retrofit installations in confined plant areas.

How does the TVA maintain accuracy at low flow rates?

The variable area design produces a linear relationship between flow rate and output signal, unlike DP-based meters which have a square-root relationship. This ensures consistent accuracy even at low flows where DP meters experience signal degradation.

What outputs are available for integration with plant control systems?

The TVA offers 4-20 mA analog output, pulse output for totalization, and optional Modbus RTU communication via RS485. A local LCD display with keypad provides on-site access to instantaneous and totalized mass or energy flow data.

SPIRAX SARCO · FLOWMETERS

Spirax Sarco TVA Target Variable Area Flowmeter for Saturated and Superheated Steam

Name: Spirax Sarco TVA Target Variable Area Flowmeter for Saturated and Superheated Steam
Brand: Spirax Sarco

Spirax Sarco TVA Flowmeter for accurate steam flow measurement with 50:1 turndown. Ideal for saturated & superheated steam in industrial plants.

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Overview

The Spirax Sarco TVA Target Variable Area Flowmeter is engineered for accurate and reliable measurement of saturated and superheated steam in industrial applications. Unlike conventional differential pressure flowmeters, the TVA utilizes a variable area design with a moving cone mechanism that maintains measurement accuracy across a wide flow range, making it suitable for processes with fluctuating steam loads.

The flowmeter features in-built automatic density compensation, eliminating the need for external pressure and temperature sensors for saturated steam applications. This integrated approach simplifies installation, reduces capital costs, and minimizes potential points of failure. The moving cone design reshapes the flow profile, allowing installation in pipework with limited straight-run availability—only 6 pipe diameters upstream and 3 downstream are required.

With a 50:1 turndown ratio, the TVA captures steam consumption across the entire operating range, from minimum to maximum flowrates. This capability is critical for comprehensive steam energy management, helping plant engineers identify inefficiencies and reduce energy waste.

Key Features

50:1 turndown ratio — measures complete steam flow range at best practice steam velocities
In-built density compensation — automatically adjusts for pressure fluctuations without external sensors
Linear output signal — maintains accuracy at low flow rates where DP meters lose precision
Minimal straight pipe requirements — only 6D upstream and 3D downstream needed
Robust moving cone design — resistant to wet steam erosion, highly reliable long-term operation
Integrated electronics — single pipe penetration point for simplified installation
ISO 17025 UKAS accredited calibration — every unit individually calibrated for guaranteed accuracy
Multiple output options — 4-20 mA, pulse output, local LCD display, optional Modbus RTU via RS485

Specifications

Parameter	Value
Turndown Ratio	50:1
Fluid Compatibility	Saturated and superheated steam
Sizes Available	DN50, DN80, DN100
Accuracy (10%–100% max flow)	±2% of measured value
Accuracy (2%–10% max flow)	±0.2% FSD
Max Operating Pressure (Horizontal)	32 bar g @ 239°C
Max Operating Pressure (Vertical)	7 bar g @ 170°C
Upstream Straight Pipe Requirement	6 pipe diameters
Downstream Straight Pipe Requirement	3 pipe diameters
Communication Options	4-20 mA, pulse, Modbus RTU (RS485)
Reference Document	TI-P192-01

Applications

The TVA Flowmeter is suitable for steam flow measurement across a wide range of industrial sectors:

- Process industries — chemical, petrochemical, and pharmaceutical plants requiring accurate steam accounting - Food and beverage manufacturing — steam consumption monitoring for cooking, sterilization, and cleaning processes - Power and utilities — boiler house steam distribution and energy management - Textile and paper mills — process steam metering for drying and heating applications - HVAC and district heating — steam flow measurement in large commercial and industrial heating systems - Energy auditing — baseline measurement and ongoing monitoring for energy efficiency programs

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