Low flow mass flow meter

Table of Content
What is low flow mass flow meter ?
Low flow mass flow meters are essential in many applications where accurately measuring small flow is crucial
Low flow Coriolis mass flow meter
The construction of low flow Coriolis flowmeter
Key features of small Coriolis flow meters designed for ultra-low mass flow measurement
Main display of the micro Coriolis flow meter
Important Considerations when installing low flow Coriolis mass flow meter
Low flow thermal mass flow meter
How low flow thermal mass flow meter work?
In which applications low flow thermal mass flow meter work?
Technical specifications of low flow thermal mass flow meter

What is low flow mass flow meter ?

A low flow mass flow meter is a special device used for measuring very small amounts of liquids or gases as they move through a system. These meters are specifically built to accurately measure flow rates as low as grams per hour or kilograms per hour.

To ensure precise measurements at such low flow rates, low flow flow meters use various technologies. Common types of these meters include positive displacement flow meters for tiny flows, small thermal mass flow meters, or mini Coriolis flow meters for extremely low mass flows.

Low flow mass flow meters are essential in many applications where accurately measuring small flow is crucial:

• 1. In pharmaceutical research and development, they assist in precisely dosing and dispensing drugs or chemicals.
• 2. In microfluidic systems used for biomedical analysis, lab-on-a-chip devices, or microreactors.
• 3. For testing fuel cells, to measure the flow rates of gases involved in the process.
• 4. In environmental monitoring systems, such as air quality monitoring or emissions testing.
• 5. In analytical instrumentation, like chromatography systems or spectrometers.

Low flow Coriolis mass flow meter

SH-CMF-FE series micro Coriolis flow meters are especially handy for measuring extremely low mass flow rates. They work by detecting the tiny deflections caused by the flow through a vibrating tube. These deflections are directly related to the mass flow rate, ensuring accuracy in measurement.

The Coriolis Mass Flow Controller excels in providing accurate measurement and precise control of fluid medium mass flow, making it indispensable across a range of industries. It plays a critical role in scientific research and production within the semiconductor and integrated circuit sectors, specialty materials fields, chemical and petroleum industries, pharmaceutical production, environmental protection, and vacuum technologies.

This flow device is particularly vital in electronic process equipment, including diffusion systems, epitaxy processes, chemical vapor deposition (CVD), oxidation, plasma etching, sputtering, and ion implantation. Additionally, it is widely used in coating equipment, optical fiber melting processes, micro-reactors, gas mixing and distribution systems, capillary measurements, and analytical instruments like gas chromatography.

The construction of low flow Coriolis flowmeter

The small Coriolis flow meter consists of primary component and secondary component.
The primary component of the system is the mass flow sensor, a position-sensitive resonant device based on the Coriolis Effect. The sensor comprises a vibrating tube (also known as the measuring tube), a signal detector, a vibration driver, a support structure, and housing.

The vibrating tube is the oscillating conduit through which the fluid flows. Signal detectors, which are critical for monitoring the Coriolis effect, come in two main types: photoelectric detectors and electromagnetic detectors.

The vibration driver is responsible for inducing oscillations in the vibrating tube. Together with the signal detector and an amplification processing circuit, it forms a positive feedback self-excited oscillation system.

The support structure, typically cast from stainless steel, anchors the vibrating tube and connects it to the mounting flange, creating a unified assembly. The housing provides protection for the vibrating tube, signal detector, and vibration driver. Most flow sensors feature a single-layer housing, but in specialized applications, double-layer protection may be employed.

The secondary component is the mass flow transmitter, an electronic system centered on a microprocessor. It supplies power to the flow sensor and converts its signals into mass flow and other relevant parameter readings. The low flow transmitter also compensates and corrects mass flow and density measurements based on temperature parameters. It typically outputs standard current or frequency signals and supports cross-linking and remote communication with a host computer or DCS system via specific communication protocols. The mini Coriolis flow transmitter's display panel can be configured to show various required parameters.

key features of small Coriolis flow meters designed for ultra-low mass flow measurement

- They maintain high accuracy even when measuring very small flows, with accuracy levels as low as 0.25% for liquid measurement and 0.5% for gas measurement.
- They offer a high turn-down ratio of up to 100:1, allowing accurate measurement over a wide range of flow rates.
- Small mass flow meters can detect mass flows as low as 40 grams per hour.
- They are made of durable materials like stainless steel 316L.
- Micro mass flow meters come in various measurement ranges, from 0 to 10 kg/h to as high as 0 to 1000 kg/h.
- Some models come with integrated PID controllers for flow regulation.
- Low flow mass flowmeters offer digital output options like 0-5V DC, 4-20mA, or 1-5V DC, and support communication protocols like RS485 or RS232.
- Some models can handle high temperatures up to 150°C.
- They are designed to be lightweight, compact, and easy to install in tight spaces or on portable systems.
- They offer various electrical connection options like DB9, RJ11, or 5.5×2.1, and can be powered by ±15VDC or 24VDC.
- They typically have a standard pressure rating of 435 psi, with a maximum pressure capacity of up to 100 bar.

Main display of the micro Coriolis flow meter

Important Considerations when installing low flow Coriolis mass flow meter

1 Adding a Filter
Ensure that the gas used is purified, avoiding contamination by dust, liquids, and oil. If necessary, install a filter before small Coriolis flow meter. When connecting a liquid source bottle to the outlet of the flow meter, a one-way valve should be installed at the outlet to prevent liquid backflow, which could damage the flow meter.

2 Use of Corrosive Gases
The small mass flow meter channel is constructed from corrosion-resistant materials such as SUS 316L (00Cr17Ni14Mo2), SUS 417J1 (00Cr30Mo2), and fluororubber. These materials can handle general corrosive environments, provided the user's system is free of steam and water, has low leakage, undergoes frequent cleaning, and is used properly. If the application involves highly corrosive or organic solvent gases, this should be specified when ordering. For special corrosive gases, all sealing materials should be appropriately adjusted.

3 Installation Locations
For optimal performance, install the small Coriolis flow controller with the mounting surface in a horizontal position. However, the small flow metering device is not overly sensitive to positioning and can be installed in any orientation. If a zero shift is observed when installed in a non-horizontal position, it can be adjusted before operation.

4 Valve Port Sealing
The solenoid valve in the small flow mass flow controller functions as a regulating valve and should not be used as a shut-off valve. Users should install a separate shut-off valve, particularly when dealing with corrosive gases, at both the inlet and outlet of the mass flow controller to ensure safe operation. After prolonged use, a leakage rate at the valve port within 2% of the full scale (F.S.) is considered normal. If the leakage exceeds 2%, repairs are necessary.

5 Calibrations and Gas Conversion
The small flow mass flow controller is typically calibrated with nitrogen (N2) at the factory. If calibration with a different gas is required, this must be specified when placing the order. For users operating the controller with gases other than nitrogen, conversions can be made using the conversion coefficients provided.

Low flow thermal mass flow meter

How low flow thermal mass flow meter work?

The exceptional accuracy, durability, and reliability of the SRK series low flow mass flow meters are attributed to our innovative sensor probes. Each sealed probe contains two critical sensing elements: a speed sensor and a temperature sensor, which work in tandem to automatically compensate for any variations in temperature and pressure.
The system operates by maintaining the speed sensor at a constant temperature above the gas temperature, measuring the cooling effect of the gas flow. The mass flow of the gas is then calculated based on the electrical power required to maintain this constant temperature difference, directly proportional to the flow rate. Both sensors utilize standard platinum resistance temperature detectors (RTD), with the platinum RTD wire securely wound around a robust ceramic core for enhanced reliability. The entire sensor assembly is encased in a 316 stainless steel housing, ensuring long-term durability and protection.

In which applications low flow thermal mass flow meter work?

Low flow thermal mass flow meters are primarily used to measure the flow of pure gases or mixed gas. These meters are highly effective in monitoring the mass flow rate of various gases, including air, nitrogen, hydrogen, oxygen, biogas, LPG, methane and carbon dioxide, among others. They are commonly deployed in applications where precise gas flow measurement is critical, such as in laboratory research, industrial gas supply systems, environmental monitoring, gas leakage detection, and semiconductor manufacturing.

These micro gas flow meters are particularly valuable in situations requiring accurate measurement of low gas flows, where traditional flow measurement technologies might struggle. Their ability to provide direct mass flow readings without the need for temperature or pressure compensation makes them ideal for use in cleanroom environments, gas chromatography, and leak detection systems, as well as in process control for chemical and pharmaceutical industries.

Technical specifications of low flow thermal mass flow meter

The low flow thermal mass flow meter offers precise gas measurement within a range of 2 SCCM to 30 SL/M, boasting an accuracy of ±1% F.S and a turn down ratio of 100:1. With a response time of less than 0.8 seconds and excellent repeatability of ±0.2% F.S, this meter ensures reliable and consistent performance.

It operates effectively within a temperature range of 0~50°C and can handle a maximum operating pressure of up to 10 MPa. The unit is built with robust stainless steel as the base material, featuring seals made from Viton, neoprene, or nitrile rubber for durability.

Communication options include RS232/485.MODBUS, with output signals available in 0~5V, 4-20mA, and 1-5V. The flow meter is powered by either ±15VDC or 24VDC, and has a temperature coefficient of ±0.025%F.S/°C. The electrical interface is provided via a DB15 connector, and the unit features a leak rate of 1×10^-9 SCCS He, ensuring high integrity in demanding applications.