If you have decided on clamp-on ultrasonic technology (start with our what is a clamp-on flow meter overview if not), the next question is almost always: portable or fixed? They use the same transit-time measurement principle — described in how clamp-on meters work — and they can give the same accuracy on the same pipe. The difference is not in the physics but in the job they are built for: a fixed meter lives on one pipe forever; a portable meter moves between many pipes. Here is how to choose.
Fixed Ultrasonic Flow Meters
A fixed (or permanent) clamp-on meter consists of a wall- or panel-mounted transmitter wired to transducers clamped permanently at one measurement point. It is powered continuously (mains/24 V), feeds the control system, and runs 24/7.
- Best for: permanent monitoring, billing/allocation, process control, BMS/SCADA integration, energy management, any point you always need data from.
- Outputs: 4–20 mA, pulse/OCT, RS485 Modbus RTU, alarms; premium models add GPRS/4G cloud logging. Hard-wired into the plant.
- Form factor: IP-rated wall-mount or panel transmitter, permanently coupled transducers. Compact integrated models exist for small pipes/OEM.
- YS-Flux models: YF-C6 fixed clamp-on (DN25–DN2000), YF-C8 premium (large mains, ±0.5%, GPRS), compact YF-C3 for small lines, and YF-E6 for permanent energy/BTU metering.
Portable Ultrasonic Flow Meters
A portable meter packages the same electronics into a battery-powered, hand-carried unit with a colour display, onboard data logger and quick-mount transducers in a carry case. It clips onto a pipe, measures for minutes or days, then comes off and moves to the next point.
- Best for: surveys and studies across many points, commissioning and hydraulic balancing, pump performance testing, verifying installed meters, temporary troubleshooting, rental/service work, and pre-purchase site checks.
- Outputs: onboard SD/USB data logging and screen readout; some support temporary pulse/analogue. Designed for standalone use rather than permanent control wiring.
- Battery: rechargeable, several to 10+ hours runtime; recharge and re-mount quickly.
- YS-Flux models: YF-P1 for general portable work; YF-P2 with the 3.5″ rotating IPS touchscreen and range up to DN5000 for large mains.
Side-by-Side Comparison
| Factor | Fixed clamp-on | Portable clamp-on |
|---|---|---|
| Intended use | Permanent, one point, 24/7 | Temporary, many points, on demand |
| Power | Mains / 24 V continuous | Rechargeable battery |
| Data output | 4–20mA, pulse, RS485 Modbus, GPRS | Onboard logger, SD/USB, display |
| Control integration | Wired to PLC/SCADA/BMS | Standalone survey tool |
| Mounting | Permanent straps/bracket, wired | Quick clamps, carry case |
| Accuracy on the pipe | Same transit-time accuracy (±0.5–1.0%); depends on installation, not portability — see accuracy guide | |
| Cost model | One per measurement point | One unit serves the whole site/fleet |
| Typical user | Plant/facility operator, utility | Service engineer, commissioning, distributor |
Key Point: Accuracy Is Not the Difference
Buyers often assume a fixed meter is more accurate than a portable. On the same pipe, correctly installed, they are equally accurate — the measurement core is identical transit-time technology. A well-mounted portable can verify a fixed meter precisely because both read to the same ±0.5–1.0% band. What differs is deployment: permanence, continuous power and hard-wired outputs (fixed) versus mobility, battery and logging (portable). Installation quality governs accuracy in both cases — follow the installation guide. And like all clamp-on, both install with no shutdown across the same pipe size range.
How to Choose
- You need continuous data from a specific point (monitoring, billing, control, alarms in the BMS) → fixed (YF-C6/YF-C8, or YF-E6 for energy).
- You measure many different pipes, or only periodically (surveys, balancing, pump tests, meter verification, troubleshooting) → portable (YF-P1/YF-P2).
- You are about to buy fixed meters but are unsure of site conditions → buy or rent a portable first: survey the points, confirm signal and flow, then specify the fixed units with confidence. Many utilities and service companies own one portable to cross-check an entire fleet of fixed meters.
- Large estates / utilities often run both — fixed meters at key billing/control points, plus a portable for audits, night-flow leakage walks and ad-hoc diagnostics.
For the full model-by-application mapping see our application selection guide; datasheets and dimensions are on the Downloads page.
Frequently Asked Questions
Is a fixed ultrasonic flow meter more accurate than a portable one?
No. On the same pipe, correctly installed, a fixed and a portable clamp-on meter give the same transit-time accuracy (typically ±0.5–1.0% of reading). The difference is deployment — fixed meters are permanently powered and wired to the control system for 24/7 monitoring, while portable meters are battery-powered for moving between points. Installation quality, not portability, determines accuracy.
When should I buy a portable instead of a fixed meter?
Choose a portable (YF-P1/YF-P2) if you measure many different pipes or only need data periodically — surveys, commissioning/balancing, pump testing, verifying installed meters, troubleshooting, or pre-purchase site checks. Choose a fixed meter (YF-C6/C8, or YF-E6 for energy) for a permanent point that feeds continuous monitoring, billing or control.
Can a portable meter verify a permanently installed meter?
Yes — this is one of the most common uses. Because a portable clamp-on reads to the same accuracy band without touching the pipe, service teams clip it on adjacent to an installed meter and compare readings. A consistent offset flags calibration drift or a fault in the fixed meter, with no shutdown required.
Portable, Fixed — or Both?
YS-Flux supplies both portable survey meters (YF-P1, YF-P2) and fixed/energy clamp-on meters (YF-C6, YF-C8, YF-E6). Tell us whether you need continuous monitoring or move-around measurement, your pipe sizes and outputs — our engineers will recommend the right set within one business day. Request a Quote →