WhatsApp: +86 16626708626
Email: 
Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Manufacturer | Panasonic Industry, formerly Panasonic Industrial Automation Sales / SUNX |
| Full Model | FM-252-4-P |
| Product Series | FM-200 integrated-display digital flow sensor |
| Measured Media | Air or nitrogen |
| Nominal Flow Range | Up to 500 mL/min; approximately 0.5 L/min |
| Display | Four-digit, two-color LCD display |
| Process Connection | 4 mm outside-diameter push-in port |
| Output Type | Two PNP switching outputs |
| Analog Output | 1–5 V |
| Supply Voltage | 12–24 V DC |
| Pressure Range | −0.09 to +0.7 MPa |
| Repeatability | Within ±1% F.S. |
| Operating Temperature | 0 to 50 °C |
| Enclosure Material | ABS enclosure with polyamide flow body |
| Enclosure Rating | IP40 |
| Mounting | Bracket mount |
| Electrical Connection | Connector type |
| Lifecycle Status | Discontinued; Panasonic lists the FM-200 product as discontinued |
Panasonic identifies FM-252-4-P as a discontinued FM-200 integrated-display digital flow sensor. Distributor technical data identifies the unit as a 500 mL/min, 4 mm-port sensor for air/nitrogen with PNP outputs and a 1–5 V analog signal.
Product Introduction
The Panasonic FM-252-4-P is an FM-200 Series digital gas flow sensor for low-flow monitoring of air or nitrogen in automation equipment. Its integrated display provides local flow visibility, while two PNP switching outputs and a 1–5 V analog output allow connection to a PLC, controller, alarm circuit, or process-monitoring system.
This sensor fits applications such as pneumatic leak monitoring, purge-gas verification, low-flow process control, semiconductor support equipment, and laboratory automation. The FM-200 Series is discontinued, so an exact FM-252-4-P replacement requires confirmation of the 4 mm port, PNP output logic, flow range, pressure rating, connector, and PLC input compatibility.
FM-252-4-P
FM-252-4-P
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to This Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| Display is blank | No 12–24 V DC supply, reversed polarity, broken cable, failed sensor | ✅ Medium | Measure DC voltage at the sensor connector using the unit wiring diagram; confirm polarity and inspect cable strain relief | Check the supply and wiring before replacing the FM-252-4-P |
| Display shows zero flow with air supply present | Blocked inlet, incorrect flow direction, insufficient differential pressure, damaged tubing, sensor contamination | ✅ High | Confirm the flow arrow and tubing direction; inspect the 4 mm tubes for kinks; compare inlet and outlet pressure; temporarily test with known clean air flow | Correct plumbing and contamination issues before replacing the sensor |
| PLC does not detect switching output | Incorrect PNP input wiring, missing PLC input common, wrong output setpoint, output load fault | ❌ Usually low | Measure the output state relative to 0 V while flow crosses the displayed setpoint; verify the PLC input expects PNP sourcing logic | Correct PLC wiring or setpoint configuration before condemning the sensor |
| Analog input remains at 1 V or 5 V | Flow is below/above measurement range, open analog lead, wrong PLC analog-input configuration, failed sensor | ✅ Medium | Measure the analog output at the sensor connector; compare voltage with displayed flow; verify the PLC channel is configured for 1–5 V rather than 0–10 V or 4–20 mA | Confirm scaling and signal wiring before replacement |
| Measured flow is unstable | Pulsating supply, pressure fluctuation, tubing vibration, water/oil contamination, electrical noise | ❌ Usually low | Monitor source pressure; inspect filters and air preparation; check for condensate; route sensor cable away from VFD motor leads | Stabilize the gas supply and remove contamination before replacing the unit |
| Displayed flow does not match a reference meter | Incorrect installation, uncalibrated reference, wrong gas type, leaks, sensor drift | ✅ Medium | Leak-test fittings; confirm the process medium is air or nitrogen; compare against a calibrated low-flow reference under steady conditions | Replace only after verifying the process setup and reference instrument |
| Sensor leaks at 4 mm port | Damaged tubing, poor tube cut, incompatible tubing, excessive side load on fitting | ❌ Low | Depressurize the line; cut tubing square; inspect tube outside diameter and fitting seal; soap-test at low pressure where permitted | Replace tubing first. Replace the sensor only if the push-in fitting itself is damaged |
| Sensor failed after installation | Overpressure, contaminated gas, incorrect wiring, ESD, mechanical impact | ✅ High | Review pressure against the −0.09 to +0.7 MPa rating; inspect for oil/water ingress; check wiring and cabinet grounding | Identify and correct the root cause before installing a replacement |
Field warning: The display can look healthy while the PLC signal is wrong. Check both paths: verify the local reading, then measure the PNP output or 1–5 V analog signal at the connector before replacing the sensor.
❗ Do not use this sensor for gases other than the specified air or nitrogen service without written confirmation. Flow calibration, material compatibility, and measurement accuracy can change with gas density, contamination, moisture, and chemical exposure.
If diagnosis remains unclear, contact technical support with photos of the front display, complete label, connector wiring, flow-arrow orientation, PLC input configuration, measured supply voltage, analog-output voltage, and the process pressure.
Frequently Asked Questions (FAQ)
What does Panasonic FM-252-4-P measure?
The FM-252-4-P measures low gas flow for air or nitrogen. Its nominal maximum flow is 500 mL/min, or 0.5 L/min, and it provides a local digital display plus discrete and analog outputs for control-system monitoring.
Is the FM-252-4-P still manufactured?
No. Panasonic lists the FM-200 integrated-display digital flow sensor family, including FM-252-4-P, as discontinued. New-surplus stock may be available, but quantities are limited and should be confirmed before scheduling equipment downtime.
Can I replace it with any 4 mm flow sensor?
No. A 4 mm port is only one compatibility point. Match the 500 mL/min range, air/nitrogen calibration, 12–24 V DC supply, PNP output logic, two switching outputs, 1–5 V analog range, process-pressure range, electrical connector, and physical installation dimensions. A sensor with NPN outputs, 4–20 mA output, or a different calibrated range may power up but will not work correctly with the existing PLC program.
Does this sensor provide both digital and analog outputs?
Yes. The FM-252-4-P provides two PNP switching outputs and one 1–5 V analog output. This allows one sensor to provide alarm or interlock signals through the PNP outputs while sending a proportional flow signal to a PLC analog-input channel. Verify the actual output wiring and PLC input scaling from the installed machine documentation.
Can I use it with a 4–20 mA PLC analog input?
Not directly. The specified analog signal is 1–5 V, while a 4–20 mA input expects current. You would need a properly engineered signal conditioner, and you must verify scaling, isolation, power requirements, and fault behavior. In many cases, choosing a replacement sensor with native 4–20 mA output is cleaner—but it may require PLC program changes and mechanical rework.
Why does the displayed reading differ from the PLC value?
Start by measuring the sensor’s analog output at the connector and comparing it against the displayed flow. Then verify that the PLC channel is configured for 1–5 V, not 0–10 V or 4–20 mA. Check the PLC scaling equation, common reference wiring, cable condition, and electrical noise. The sensor may be fine; the PLC could simply be interpreting a valid 1–5 V signal with the wrong range.
Why is a new-surplus FM-252-4-P cheaper than a current replacement?
The model is discontinued, so new-surplus units are stored legacy inventory rather than current factory production. Pricing reflects availability, storage condition, packaging, test level, warranty, and market demand. Request actual item photographs, the full Panasonic label, connector condition, display power-up verification, output test evidence, and written warranty terms.
How should a supplier test a surplus flow sensor?
A useful test includes visual inspection of the resin body and 4 mm fittings, power-up on a regulated 12–24 V DC supply, display verification, controlled air-flow comparison, PNP output switching at a defined setpoint, 1–5 V analog-output measurement, and leak inspection at approved pressure. The supplier should package the unit to prevent port damage and provide test photos or video on request.
