Description
QT811 ultrasonic flow meter adopts a new external clamp design, which could get the flow rate without touch the measurement medium. As the advantage of a clamp on flow meter, no need to cut off the pipe or long time stop the equipment, save the cost of time and labor costs. Easily and friendly for installation and operation, QT811 could not only work as flow meter, but also BTU meter to realize the monitoring of flow and energy.
Advantages
Comparing with other traditional flow meter, QT811 ultrasonic flow meter is specially designed for small pipe sizes clamp on flow measurements. It is integrated design with the monitor LCD and the sensors in one body, user could read flow rate directly from the device. With various kinds of outputs including 4-20mA, OCT pulse and RS485 modbus, ultrasonic flow meter could achieve remote monitoring in central control room.
Technical Data
Clamp On Ultrasonic Flow Meter Parameters
| Size | DN15-DN40 (1/2″- 1 1/2″) |
| Accuracy | ±1% of measured value |
| Flow Range | ±0.1m/s ~ ±5m/s |
| Fluid | Single medium liquid |
| Pipe Material | Metal / PVC, PP or PVDF rigid plastic pipe |
| Power Supply | 10-24V VDC |
| Electric Power | < 3W |
| Data Storage period | 300ms |
| Memory for data backup | EEPROM (Data storage: over 10 years, data read/write frequency: over 1 million times) |
| Protective circuit | Power reverse connection protection, Power surge protection Output short circuit protection, Output surge protection |
| Outputs | 4-20mA, OCT (optional) |
| Communication | RS485 |
| Power and IO connection | M12 type aviation plug |
| Medium Temperature | 0-75℃ |
| Humidity | 35 to 85% RH (No condensation) |
| Vibration resistance | 10~55Hz double amplitude 1.5 mm, 2 hours in each XYZ axis |
| Environment temperature | -10 to 60°C (No freezing) |
| Protection | IP65 |
| Main material | Aluminum, Industrial Plastics |
| Cable Length | Signal cable 2m (standard) PT1000 sensor standard cable length 9m |
Size Drawing (Unit: mm)

Parts
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Clamp On Ultrasonic Flow Meter Dimension
| QT811 | Specification | Code | ||
| Type of Transmitter | Ultrasonic Flow Meter | 1 | ||
| Ultrasonic Energy/Btu Meter | 2 | |||
| Output (Choose 2 out of 4) | 4-20mA | A | ||
| Modbus(RS485) | M | |||
| OCT(Frequency) | O | |||
| 1 Relay | R | |||
| Temperature Sensor | Without PT1000 sensor | WT | ||
| Another side cable length 9m | P | |||
| Another side cable length 15m | P15 | |||
| Another side cable length 25m | P25 | |||
Installation
Try not to disturb the upstream flow distribution. Ensure no valves, elbows or triplets; try to install the control devices or throttles in the downstream if any, so as to ensure sufficient pipe flow at the measurement point, details are shown below:





