Arrow Hunter PLUS – Portable BTU Energy Flowmeter

The ECHO Arrow Hunter PLUS range of non-invasive flowmeters utilizes Transit-time ultrasonic technology for the accurate flow measurement of clean or dirty liquids in full pipes. The AH+BTU is designed for simple portable applications where flow display and data logging are the only requirements. Includes case and mounting straps.



•   All-in-One Portable Thermal Energy Measurement using non-intrusive (clamp-on) flow and temperature sensors with an integral energy meter

•   Advanced Transit-time Technology with +/- 0.5% Accuracy and certified Class A Clamp-on Temperature Sensors

•   Dual Channel Meter measures flow in all metal, composite & plastic pipes 0.25″ – 118″ diameters with or without liners

•   Dual DSP Microprocessor with digital signal noise rejection

•   Portable enclosure with graphical display and large data logging capabilities

•   Easy to install clamp-on sensors – usually reading energy and flow within 30 minutes time

The ECHO Arrow Hunter Plus range of non-invasive flowmeters utilize transit-time ultrasonic technology for the accurate flow measurement of clean or dirty liquids and liquefied gases in full pipes.  The AH+BTU is a single source Portable Thermal Energy Meter with Class A certified insertion or clamp-on temperature sensors and precise flow for a complete Energy Measurement Solution.  This meter will monitor off-peak, extremely low flows down to 0.03 ft/s.

The AH+BTU is designed for portable applications where quick setup, accurate flow testing and reliable energy measurement are the primary requirements.  The unit is simple, light-weight and cost-effective.  It meets and exceeds the measurement performance of any competitors flowmeter on the market today.

The measurement of flow is based on the principle that sound waves are influenced by a flowing medium.  Measurements are made by penetrating the pipe with ultrasound and measuring the  frequency variations and phase shifts of the signals received.  This measuring technique has no effect on the flowing medium. There is no pressure loss in the pipe and no wear on components of the measuring device.

The ultrasonic and temperature sensors are clamped onto the outside of the pipe, thus eliminating the need to dismantle the pipe work and interrupt the process.  The AH+BTU can be applied to any type of metal or plastic pipe with or without a liner carrying clean or dirty liquids.  We have several transducers to chose from depending on pipe size, process temperature and required hazardous approvals.

ECHO Process Instrumentation offers a 60 day Performance Guarantee! 


  •  Certified and Highly Accurate Portable Energy Flowmeter
  •  Measurement is independent of fluid conductivity
  •  No pressure loss, no possibility of leakage
  •  Easily retrofits failed mag meters in older plants
  •  No cutting of pipes necessary, no interruption of process, no plant shut down
  •  No additional fittings for maintenance required
  •  Hygienic measurement, no risk of contamination, suitable for ultra clean liquids
  •  No contact with medium, no risk of corrosion when used with aggressive media
  •  Cost advantages when used with large diameter pipes, high pressure systems, etc.



Technical Specs:  Arrow Hunter PLUS – Portable BTU Energy Meter


Measuring principle : Ultrasonic Transit-time
Flow velocity range : 0.03 … 82 ft/s (0.01 … 25 m/s)

Resolution : 0.00082 ft/s (0.25 mm/s)
Repeatability : 0.15 % of measured value ±0.015 m/s
Accuracy : Volume flow :  ± 0.5% factory calibrated (process conditions can reduce accuracy),
± 0.5% of measured value with process calibration
                 Flow velocity : ± 0.5 % of measured value
Turn down ratio : 1/100
Max particulates : < 10 % of volume

Flow transmitter

Enclosure : Portable

Protection rating : NEMA 12 (IP 65 according EN60529)
Operating temp. : 14 …140 °F (-10 … 60 °C)
Housing material : Extruded aluminum, lids are zinc alloy
Flow channels : 2
Power supply :  Internal rechargeable batteries, 8 x NiMH AA 2850 mAh or 9 VDC external power supply
Display : LCD graphic display, 128 x 64, backlight
Dimensions : 10.5 H x 6.6 W x 1.5 D inch (266 H x 168 W x 37 D mm)
Weight : Approx. 4.4 lbs (2 kg)
Power consumption: < 1 W in measurement mode
Signal damping : 0 … 99 s
Measurement rate : 10 … 1000 s-1
Operating languages: English, German, French, Spanish
Response time : 1 s, faster rates upon request

Quantity and units of measurement

Volumetric flow rate : m3/h, m3/min, m3/s, l/h, l/min, l/s, USgal/h, USgal/min, USgal/s, USMGD, bbl/d, bbl/h, bbl/min, bbl/s
Flow velocity : m/s, ft/s, inch/s
Mass flow rate : g/s, t/h, kg/h, kg/min
Volume/ Mass : m³, l, US gal, bbl / g, kg, t
Heat flow         : W, kW, MW
Heat quantity   : J, kJ, MJ, BTU, MBTU, MMBTU

Internal data logger

Storage capacity : > 100,000 samples (512 kByte)
Logging data : All measured and totalized values


Serial interface : RS 232, (optional RS 485)
Data : Instantaneous measured value, parameter set and configuration, logged data

Software AH+ PC Software

Functionality : Downloading of measured values/parameter sets, graphical presentation, list format, export to third party software, on-line transfer of measured data
Operating systems : Windows 2000, NT, XP, Vista, 07

Process inputs (Galvanically Isolated)

Temperature                :  PT100, four-wired circuit, measuring range –50 … 400˚C, resolution 0.1K, accuracy +/- 0.2 K

Process outputs (Galvanically Isolated)

Current                         :   0/4 … 20mA, active, 500Ω, 16 bit, U = 30V, accuracy 0.1%

Digital Pulse               :   (Open Collector) Totalizer, 0.001 … 1000/unit, width 30 … 999ms, U=24V, Imax = 4 mA

Relay                            :   Alarm, fault (programmable), Form C       (SPDT-CO), U=48V, Imax = 250mA

Serial                            :   RS232 only




Clamp-on Sensors


Pipe Diameter range: 0.25 … 9.8 inch (10 … 250 mm)
Dimensions : 1.7 x 0.7 x 0.8 inch (43x18x22mm)
Material : Stainless Steel
Temperature range :    Type XTT+SM-P: -22 … 266 °F (-30 … 130 °C)

Protection rating : NEMA 6P (IP 68) submersible

Hazardous rating : General Purpose


Pipe Diameter range: 1.96 … 118 inch (50 … 3000 mm)
Dimensions : 2.3 x 1.2 x 1.3inch (60x30x34 mm)
Material : Stainless Steel

Temperature range : Type XTT+LG-P: -22 … 266 °F (-30 … 130 °C)

Protection rating : NEMA 6P (IP 68) submersible

Hazardous rating : General Purpose



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