testo 6451 – Compressed Air Meter DN15 (½″) for Consumption, Flow, Pressure and Temperature Measurement

The testo 6451 is a stationary compressed air meter for continuous monitoring of compressed air consumption and operating conditions in industrial compressed air systems. The device combines four important measured variables in one compact measuring system: volumetric flow, total consumption, temperature and operating pressure.

This makes the testo 6451 suitable for consumption measurement as well as leak monitoring, consumption-based allocation of compressed air costs and analysis of peak loads. Transparent monitoring of compressed air consumption helps identify potential savings and enables better assessment of compressed air generation capacity utilization.

Four Measured Variables with One Device

The testo 6451 simultaneously measures:

• Volumetric flow of the compressed air
• Total consumption via the integrated totalizer
• Medium temperature
• Operating pressure

For many applications, this eliminates the need for an additional separate pressure measurement. The standard TFT display can show up to three measured values simultaneously directly at the measuring point.

Calorimetric Flow Measurement

Flow measurement is based on the calorimetric measuring principle. This allows measurement without any moving mechanical parts. The integrated measuring section provides defined flow conditions and reduces installation-related measurement deviations.

For the testo 6451 in the DN15 version, the measuring range is:

• Volumetric flow: 4 … 1,250 l/min
• Standard volumetric flow: 0.25 … 75 m³/h
• Flow velocity: 0.3 … 99.8 m/s

The specifications for volumetric flow, display and settings refer to standard volume according to DIN ISO 2533.

Integrated Pressure and Temperature Measurement

In addition to compressed air consumption, the testo 6451 also monitors the current operating pressure and medium temperature.

Measured variable	Measuring range
Volumetric flow	4 … 1,250 l/min
Standard volumetric flow	0.25 … 75 m³/h
Flow velocity	0.3 … 99.8 m/s
Totalizer	0 … 100,000,000 m³
Operating pressure	-1 … +16 bar
Temperature	-10 … +60 °C

Direct Integration into Control and Monitoring Systems

For further processing of the measured values, two scalable 4 … 20 mA analog outputs are available. These can be used to transmit flow, pressure or temperature, for example, to a PLC, process control system, data logger or energy management system.

The testo 6451 is supplied with an operating voltage of 18 … 30 V DC. Maximum current consumption is less than 80 mA.

Making Compressed Air Consumption Transparent

Continuous consumption measurement enables, among other things:

• Measurement of compressed air consumption for individual machines or plant sections
• Consumption-based allocation of compressed air costs
• Detection of unusually high consumption
• Support for leak monitoring
• Analysis of peak loads
• Monitoring of available compressed air generation capacity
• Evaluation of energy-saving measures
• Implementation of continuous compressed air monitoring

The compressed air meter can therefore also make an important contribution to operational energy and environmental management, for example within management systems according to ISO 50001 or ISO 14001.

Technical Data testo 6451

Technical characteristic	testo 6451
Order number	0555 6451
Nominal diameter	DN15 (½″)
Process connection	R ½ thread
Flow measuring principle	Calorimetric
Volumetric flow	4 … 1,250 l/min
Standard volumetric flow	0.25 … 75 m³/h
Flow velocity	0.3 … 99.8 m/s
Flow resolution	1 l/min / 0.1 m/s / 0.05 m³/h
Totalizer	0 … 100,000,000 m³
Pressure measuring range	-1 … +16 bar
Pressure resolution	0.05 bar
Temperature measuring range	-10 … +60 °C
Temperature accuracy	±0.5 K
Medium	Compressed air
Medium temperature	-10 … +60 °C
Pressure rating	16 bar
Minimum burst pressure	64 bar
Outputs	2 × 4 … 20 mA, scalable
Maximum load	500 Ω
Power supply	18 … 30 V DC
Current consumption	< 80 mA
Display	1.44″ color display, 128 × 128 pixels
Ambient temperature	0 … +60 °C
Storage temperature	-20 … +85 °C
Ingress protection	IP65 / IP67
Weight	approx. 728.5 g

Volumetric Flow Measurement Accuracy

The achievable measurement accuracy depends on the compressed air quality. Testo specifies the following values at a medium temperature of +23 °C:

• Compressed air class 1-4-1 according to ISO 8573-1:2010: ±(2 % of reading + 0.5 % of full scale)
• Compressed air class 3-4-4 according to ISO 8573-1:2010: ±(6 % of reading + 0.6 % of full scale)
• Repeatability: 0.8 % of reading + 0.2 % of full scale

Typical Applications

• Compressed air consumption measurement in production plants
• Consumption monitoring of individual machines and consumers
• Energy and cost monitoring
• Leak monitoring
• Peak-load analysis
• Monitoring of the compressed air supply
• Energy management according to ISO 50001
• Environmental management according to ISO 14001

Advantages of the testo 6451

• Four measured variables with just one measuring instrument
• Integrated pressure measurement
• Integrated inlet and outlet measuring section
• Direct local indication via TFT color display
• Simultaneous display of three measured values
• Two scalable 4 … 20 mA outputs
• Calorimetric measuring principle without moving wear parts
• Easy integration into existing compressed air systems
• Suitable for continuous energy and consumption monitoring

Scope of Delivery

• testo 6451 compressed air meter DN15 (½″)
• integrated inlet/outlet measuring section
• integrated pressure measurement
• analog outputs
• operating instructions

The testo 6451 is therefore particularly suitable for operators who not only want to measure the current compressed air flow, but also continuously monitor consumption, pressure and temperature and make compressed air costs transparent.