Thermal Gas Flow Meter, 0~2/20/100L/min, RS485 Modbus

This thermal gas flow meter offers three flow ranges (0-2, 0-20, 0-100 L/min) with RS485 Modbus, 4-20mA, and 1-5V outputs. Includes internal alarm and LCD display. Ideal for laboratory, industrial, and IoT gas measurement.

SKU: T-FLOW-AMS

Flow Range *
Output Signal *
Accuracy

$455.63

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Delivery date: 6-12 days

Overview
Reviews

Overview

The thermal gas flow meter with RS485 Modbus interface offers a comprehensive solution for laboratory, industrial, and IoT gas measurement. Three selectable flow ranges: 0.02–2 L/min, 0.2–20 L/min, and 1–100 L/min, allow precise measurement across diverse applications with a single device.

Specification

Model	T-AMS1000A02	T-AMS1000A01	T-AMS1000A03
Accuracy	±4%RD (0.02-0.5L/min) ±2%RD (0.5-2L/min)	±4%RD (0.2-20L/min) ±2%RD (5-20L/min)	±4%RD (1-25L/min) ±2%RD (25-100L/min)
Measuring Medium	Dry, clean, and non-corrosive gases such as air, oxygen, argon, nitrogen, and carbon dioxide (excluding flammable and explosive gases)
Maximum Working Pressure	0.8MPa
Nominal Diameter	G1/4
Working Temperature	-10°C～+60°C
Repeatability	±1%F.S.
Response Time	50ms
Standard Calibration Gas	Air (25℃, 1 standard atmospheric pressure)
Signal Output	Default RS485+4-20mA/RS485+1-5V (optional)
Communication Method & Protocol	RS485, MODBUS-RTU
Power Supply	<0.85W
Display Mode	LCD display
Housing Material	PC
Duct Material	Aluminum
Net Weight	Approx. 330g

Key Features

±2%RD accuracy ensures reliable experimental results and process control.
50ms response time captures real-time flow fluctuations for dynamic automation environments.
Three selectable ranges cover both low-flow leak detection and high-velocity industrial demands, reducing inventory costs.

Dimension (unit: mm)

Thermal mass air flow meter dimension drawing with mounting hole locations and overall size specifications

Structure

Thermal gas mass flowmeter internal structure diagram and key components

Interface Definition

Thermal mass air flow meter interface definition pinout and wiring diagram

Pin	Lead Wire Color	Definition
1	Orange	External output 1
2	Brown	Analog output
3	Green	RS485B
4	Yellow	RS485A
5	Red	Power supply cable
6	Black	GND
7	Blue	GND
8	Purple	GND
9	Gray	External output 2
/	Transparent Heat Shrink Sleeve	Shielded cable

Piping Methods

Thermal mass flow meter for natural gas piping methods and installation guide

Straight pipe requirement – For the tubing connected to the inlet and outlet ports of the AMS1000 series, always reserve the straight pipe section as specified in the table below. Failure to do so may cause an accuracy deviation of ≥3% F.S.

Orientation of the flow meter duct – The duct of the T-AMS1000 series should be installed either parallel or perpendicular to the horizontal plane.

When installed parallel to the horizontal plane, the device interface must be positioned above the duct and also parallel to the horizontal plane.
For other installation angles, please contact our customer support.

This thermal mass flow meter for air (RS485 Modbus) requires the following straight pipe lengths: for AMS1000A01/A02/A03 – inlet ≥12.5 cm, outlet ≥6.25 cm.

Application

Thermal mass meter application scenarios in medical, agriculture, and petroleum industries

FAQ & Solutions for Thermal Mass Flow Meter

Question for Thermal Mass Flow Meter	Solutions for Thermal Mass Flow Meter for Natural Gas
Flow rate reading is inaccurate – too high, too low, or no flow at all	Check if the piping meets the requirements in the datasheet
	Verify that the gas type being used is correct
	Ensure the gas pressure meets the minimum driving standard of 0.1 MPa
	Make sure the installation environment is free from vibration or interference
Inlet and outlet pipe requirements	For accurate measurement, the inlet of the gas mass flowmeter must be connected to a sufficiently long straight pipe. Refer to the datasheet for detailed installation instructions. The installation area should be free from vibration and electromagnetic interference
Different readings from two flow meters on the same pipeline due to different positions	Different positions along the same pipeline experience different flow resistance (pressure drag), which can cause significant reading variations. To minimize this, ensure consistent installation orientation and sufficient straight pipe sections
What types of gas can this flow meter handle	This thermal mass meter is designed for single-component gases only. Mixed gases cannot be measured accurately. The gas must be dry, clean, and free from moisture or oil vapor

AMS1000 Troubleshooting – Thermal Mass Air Flow Meter

Fault Indication	Possible Cause	Corrective Action
No display on the main interface	Power and ground wires are not connected as required Insufficient power supply (needs +9V to +24V DC) Display screen defective	Connect correctly per wiring instructions Provide a proper +9V to +24V DC power supply Check the display for physical damage
Non‑zero instantaneous flow reading before measurement	Valve on the installation pipeline not fully closed Air leak in the connected pipeline	Check that the pipeline valve is fully closed Inspect the pipeline for air leaks
No flow recorded	Blockage in the pipeline No gas flow inside the pipeline	Check for foreign material blocking the pipeline Confirm the pipeline valve is open and gas is flowing
Reduced flow reading	Blockage Contaminated flow sensor	Check inlet/outlet ports for obstruction Clean or replace the thermal mass flow meter for air affected(refer to maintenance guide)
Communication failure	Incorrect wiring of the thermal mass meter Wrong baud rate setting RS485 not working properly Modbus RTU address incorrectly set	Wire correctly as per the instruction manual Set the host baud rate to 9600 bps Confirm the RS-485/RS-232 converter is functioning Set the correct Modbus address as required

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