Clamp-on BTU meter on a chilled water supply/return pair — no pipe cutting, no system shutdown
Quick Answer: Clamp-on ultrasonic BTU meters combine transit-time flow measurement with PT1000 temperature sensors on the supply and return lines to calculate real-time thermal energy — without cutting any pipe or stopping the system. Soaring Instrument offers three configurations covering pipe sizes DN15 to DN1200.
How It Works
A clamp-on BTU / energy meter uses two complementary measurements:
- Flow rate: Transit-time ultrasonic transducers clamp onto the pipe exterior and measure liquid velocity from the time difference between upstream and downstream pulses — no pipe penetration required
- Temperature differential (ΔT): PT1000 RTD sensors clamp onto the supply and return lines to measure the temperature difference
The meter calculates thermal energy continuously:
Thermal Power (kW) = Flow Rate × ρ × Cp × ΔTFluid properties (density ρ, specific heat Cp) are automatically applied for water and water/glycol mixtures.
How transit-time ultrasonic flow meters work →
Three Product Configurations
We offer three clamp-on BTU meter configurations. All support the optional RTD module + PT1000 temperature sensors to enable the energy meter function.
From left: Wall-Mount (DN25–DN1200), Small Pipe (DN15–DN65), and Portable (DN15–DN1200) clamp-on BTU meter configurations
1. Wall-Mount Clamp-On BTU Meter — DN25 to DN1200
Our flagship permanent installation unit, suitable for most commercial and industrial HVAC energy metering.
| Parameter | Specification |
|---|---|
| Pipe Size | DN25–DN1200 (standard); DN15–DN40 with separate sensor set |
| Flow Range | ±0.03 m/s ~ ±12 m/s |
| Flow Accuracy | ±1% of measured value |
| Repeatability | 0.2% of measured value |
| Measurement Rate | >300 times per second |
| Display | 240×128 backlit LCD |
| Analog Output | 4-20mA (max load 750Ω) |
| Pulse Output | 0–10 kHz |
| Communication | RS232/RS485 Modbus (M-Bus or HART optional) |
| Power Supply | DC 10–36V / AC 90–245V |
| Transmitter Protection | IP65 (PC+ABS enclosure) |
| Transducer Protection | IP68, double-shielded cable |
| Humidity | Up to 99% RH, non-condensing |
Energy Meter Option: Add RTD module + PT1000 temperature sensor → measures heat and cold consumption of heating pipelines and air-conditioning refrigeration pipelines. PT1000 uses high-temperature resistance cables.
Transducer options by temperature range:
| Model | Pipe Size | Temperature Range |
|---|---|---|
| TT01 / TT02 | DN25–DN1200 | -40°C ~ +80°C |
| TT03 | DN25–DN1200 | -40°C ~ +130°C |
| TT02H | DN25–DN1200 | -40°C ~ +180°C |
| TT05 (insertion) | DN25–DN1200 | -40°C ~ +130°C |
| TT02S | DN15–DN40 | 0°C ~ +65°C |
| TT03S | DN15–DN40 | 0°C ~ +115°C |
2. Small Pipe Clamp-On BTU Meter — DN15 to DN65
Purpose-designed for small-diameter terminal units and compact HVAC circuits.
| Parameter | Specification |
|---|---|
| Pipe Size | DN15–DN40 (standard); DN50–DN65 (available) |
| Compatible Pipe Material | Stainless steel, carbon steel, copper, PVC, other rigid plastics |
| Compatible Fluid | Water, oil, chemicals (single-phase liquid, no solid particles) |
| Temperature Range | Standard: -10°C ~ 65°C; High-temp type: -10°C ~ 115°C |
| Flow Accuracy | ±2% (±1% after calibration) |
| Low Velocity Cut-Off | 0.1 m/s (factory default) |
| Output | 4-20mA |
| Communication | Modbus RS485 |
| Power Supply | 10–24V DC |
| Protection Class | IP65 |
| Display | 256×128 LCD |
| PT1000 Sensor Cable | 9m standard |
| Data Memory | EEPROM (>10 years retention) |
Energy Meter Option: Optionally configured as ultrasonic cooling/heat meter, BTU meter, or energy meter for monitoring energy consumption on small pipe circuits.
Small pipe ultrasonic flow meter guide →
3. Portable Clamp-On BTU Meter — DN15 to DN1200
Handheld unit for energy commissioning, audits, and temporary monitoring. Add the optional RTD module + PT1000 clamp-on temperature sensors to enable use as a portable energy meter / cold (heat) meter.
| Parameter | Specification |
|---|---|
| Pipe Size | DN15–DN1200 |
| Flow Range | ±0.01 m/s ~ ±12 m/s |
| Flow Accuracy | ±1% of measured value |
| Power | Rechargeable lithium battery, 3000mAh (16 hours continuous) |
| Data Logger | Built-in 32G SD card with data analysis software |
| Transmitter Protection | IP54 |
| Transducer Protection | IP68 |
| Transducer Cable | 5m standard |
| Energy Meter Option | Add RTD module + PT1000 clamp-on temperature sensors |
Portable clamp-on flow meter installation guide →
Select by Application
| Application | Recommended Configuration |
|---|---|
| Chilled water loop sub-metering (permanent) | Wall-Mount BTU Meter, TT01/TT02 sensors |
| Hot water / heating system (permanent) | Wall-Mount BTU Meter, TT03 sensors |
| High-temperature steam condensate | Wall-Mount BTU Meter, TT02H sensors |
| Fan coil unit / small terminal (DN15–DN40) | Small Pipe BTU Meter |
| Energy commissioning / audit | Portable BTU Meter + RTD module |
| District heating billing | Wall-Mount BTU Meter with M-Bus option |
| BEMS / SCADA integration | Wall-Mount or Small Pipe, RS485 Modbus |
What are the key applications of clamp-on ultrasonic BTU meters? →
Why Clamp-On vs. Inline BTU Meters
| Factor | Clamp-On | Inline (Wetted) |
|---|---|---|
| Pipe cutting required | ❌ No | ✅ Yes |
| System shutdown required | ❌ No | ✅ Yes |
| Fluid contact | ❌ None | ✅ Yes |
| Relocatable | ✅ Yes | ❌ No |
| Pressure drop | Zero | Some |
| Moving parts | None | None |
Inline vs. clamp-on ultrasonic flow meter differences →
Frequently Asked Questions
What is the pipe size range for clamp-on BTU meters?
Soaring Instrument clamp-on BTU meters cover DN15 to DN1200. The small pipe model handles DN15–DN65; the wall-mount and portable models cover DN25–DN1200 (DN15 with additional sensor set).
Can the clamp-on BTU meter measure both heating and cooling?
Yes. The meter calculates energy transfer in both directions — positive (heating) and negative (cooling) — and can display separate accumulated totals for each mode.
What communication protocols are supported?
The wall-mount model supports RS232/RS485 Modbus as standard, with M-Bus and HART available as options. The small pipe model supports Modbus RS485. The portable model uses RS485 Modbus.
Does the energy meter function require any pipe modification?
No. The PT1000 temperature sensors clamp directly onto the pipe exterior on the supply and return lines. No pipe tapping, welding, or drain-down is required.
What fluids are compatible?
Designed for single-phase clean liquids: water, water/glycol mixtures, and common industrial liquids. Not suitable for high-solids slurries or two-phase flow.
Ready to Select Your BTU Meter?
Contact us for application-specific configuration →
View the full ultrasonic flow meter range →
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