ST501 Water Treatment System Utilizing Adaptive Signal Processing to Maintain Measurement Accuracy in Variable Flow Conditions
ST501 Stationary Ultrasonic Flowmeter
Integrate into your management system to provide remote measurement services.
Cost-Effective Fixed Ultrasonic Flowmeter ST501
Introduction
ST501 Ultrasonic flow meter uses the most reliable digital signal processing technology, transmitting flow measurement for a wide range of liquid and pipe size with high accuracy and reliability. Combined the outstanding performance transducer with higher industrial level material, Flo-Instruments can have long time work without any worries.
Clear menu display selections make use of instruments very convenient. Clamp-on transducers makes the unit more flexible over a wide range of applications.
The ST501 ultrasonic flowmeter is based on Transit-Time technology, which has high measurement accuracy. ST501 uses a clamp-on transducer, which can collect flow data simply by clamping it on the outside of the pipe, and it will never come into contact with the fluid, and will not cause liquid pollution, pressure reduction, leakage, etc.
Benefits
- Measures the actual flow and total consumption ofvarious liquids
- No loss of process control, optimization of assets and efficiency, no downtime or expense from calibration
- Adaptive signal processing algorithms optimize performance, ensuring accurate measurements even in challenging flow conditions.
- Clear display interface and LCD display with alarm function, easy to operate and debug
- Utilize transit-time ultrasonic technology so as to realize bidirectional flow measurement by precisely measuring the time it takes for ultrasonic signals to travel upstream and downstream
- Leverage the data logging capabilities to analyze historical flow patterns to make system optimization.
- Built-in keypad and simple menu system for fast and easy programming of pipe diameter, pipe material, liquid type, and measurement units.
Principle
- Introduction to TVT
The Transit-Time Ultrasonic Flow Meter, also known as Time-of-Flight (TVT) ultrasonic flow meter, is a non-intrusive flow measurement technology widely used for clean liquid applications. It operates on the principle of measuring the time difference between ultrasonic signals transmitted in the direction of flow and against the flow direction.
The device has a pair (or more) of ultrasonic transducers installed on the exterior of the pipe (clamp-on) or inserted in-line. One transducer sends an ultrasonic pulse downstream with the flow, while the other sends it upstream, against the flow. Since the fluid's movement affects the transit time of the ultrasound, the time difference between the two signals is directly proportional to the flow velocity.
Product Dimension
| Transmitter |
![]() |
| Transducer |
![]() |
Wiring Instructions
Open the cover can be found at the right lower side, connect to DC power terminal.
As per wiring diagram to connect:
RTD input (only for Energy Model), RS485, 4-20mA, Transducer (Upstream transducer, Downstream transducer), Relay Output, OCT Output.
For double-shielded transducer cable: "+" on the blue wire, "-" on the white wire and "shield" on the shield.
![]() |
Communication and Output Functions
The ST501 Fixed Ultrasonic Flow Meter is equipped with multiple communication and output options to ensure seamless integration into various industrial control systems. These outputs enable real-time data acquisition, remote monitoring, and control of flow-related processes.
Summary of Output Capabilities
| Output Type | Function | Application Examples |
| RS485(Modbus) | Digital communication | Remote monitoring, SCADA, system integration |
| 4-20mA | Analog output | PLC input, process feedback, DCS systems |
| OCT Pulse | Flow totalization output | Batch controllers, energy meters, flow loggers |
| Relay | Alarm/ control output | Trigger alarmscontrol valves/ pumps, flow safety protection |
Specifications
| Performance specifications | |
| Velocity range | 0 ~ ±16ft/s (0 ~ ±5m/s) |
| Accuracy | ±1.0% |
| Pipe size | Clamp-on: 1’’~48’’ (25mm~1200mm) |
| Fluid | Sea Water, Kerosene, Gasoline, Oil, Alcohol, ect |
| Pipe material | PVC, Carbon Steel, Stainless Steel, ect |
| Function specifications | |
| Optional Outputs | OCT Pulse output: 0~5000Hz. |
| Analog output: 4~20mA, max load 750Ω. | |
| Communication interface | RS485 |
| Power supply | 24V DC/1A |
| Keypad | 16(4×4) key with tactile action |
| Display | 20×2 lattice alphanumeric, back lit LCD. |
| Temperature | Transmitter: 32℉~140℉ (0℃~60℃) |
| Transducer: 32℉~140℉ (0℃~60℃) | |
| Humidity | Up to 99% RH, non-condensing |
| Physical specifications | |
| Transmitter | Aluminum Alloy, IP65. |
| Transducer | Encapsulated design, IP68. |
| Transducer cable | Standard cable length: 33ft (10m). |
| Weight |
Transmitter: approximately 0.7kg; Transducer: approximately 0.4kg |
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.




