Oxygen(O2) Flow Meter Types and Selection Guides

What should I consider when measuring oxygen flow?

The core of measuring oxygen flow rate lies in "safety, accuracy, and adaptability to working conditions".

Oil Free oxgen flow meter with ATEX approved

O2 gas flow measurement needs ATEX certified flow meter

Safety is the primary prerequisite. Oxygen is a combustion supporting gas that can easily cause danger when in contact with grease and impurities. Therefore, flow meters must meet the requirements of oil-free cleanliness, and the material must be compatible with oxygen and flow meter should be ATEX approved gas flow meter.

Accurate measurement O2 flow meter

Gas measurement accuracy is also very important, with different scenarios requiring different error ranges; Industrial production typically requires an accuracy of ± 1% to ± 2.5%.

Match oxygen flow meter to conditions

It is necessary to select the corresponding type based on parameters such as oxygen state (gaseous/liquid oxygen), pressure, temperature, flow range, etc., in order to avoid measurement failure or equipment damage caused by mismatched operating conditions.

What are the main types of oxygen flow meters?

At present, the mainstream oxygen flow meters are mainly divided into three core models, each with clear adaptation scenarios and unique advantages, which can cover the measurement needs of most gaseous oxygen;

At the same time, specialized models are also available for special working conditions to ensure accurate and safe measurements in different scenarios.

Thermal mass flow meter for O2 flow measurement

Thermal mass flow meter for O2 gas

How thermal mass flow meter work for oxygen gas ?

SRK-100 series Thermal gas flowmeter, which is a versatile tool for measuring gaseous oxygen. Its core advantage lies in its strong adaptability and convenient use. Its working principle is to sense the heat loss during oxygen flow through heating elements and temperature sensors, and then convert it into flow data.

What is the advantages to use thermal mass flow meter for oxygen gas ?

• It is good for small and medium flow conditions - whether it is a conventional small and medium flow rate of several cubic meters to tens of cubic meters per hour, or a small flow rate scenario as low as 10 sccm , it can stably output data.
• It can capture flow fluctuations in real time, making it particularly suitable for industrial production processes that require dynamic flow monitoring;
• The pressure loss is minimal and will hardly affect the overall pressure balance of the oxygen delivery system.
• Multiple installation methods such as insertion or pipeline O2 flow meter can be flexibly selected.
• Easy maintenance, only regular cleaning of the sensor probe is required, greatly reducing operation and maintenance costs.
• It can also adapt to different pressure conditions, working normally in medium and high pressure environments ranging from atmospheric pressure to tens of bars. The oxygen gas flow sensor wet parts material is mostly made of 316L stainless steel, fully meeting the requirements of oil-free cleaning and corrosion prevention for oxygen measurement.

Metal tube Rotameter for O2 flow measurement

Rotameter for O2 Gas

How rotameter works for O2 flow measurement?

Metal tube rotameter, which can be regarded as the "practicality" in oxygen measurement, and is favored for its simple structure and high cost-effectiveness. Its measurement principle is based on the balance of buoyancy and gravity, and the flow rate is indicated by the lifting position of the rotor inside the conical metal tube. The reading is intuitive and clear, and on-site operators can quickly read the data without professional training.

What is the advantages to use variable area flow meter for O2 ?

This type of flowmeter is particularly suitable for measuring low to medium flow rates at room temperature and pressure, such as monitoring the output flow rate of small oxygen production equipment and controlling the flow rate of oxygen distribution branches in workshops. The range is usually between 0.1 cubic meters and 100 cubic meters per hour, which can meet the oxygen needs of most small and medium-sized devices.

The outer shell and inner tube are mostly made of stainless steel material, which has strong corrosion resistance and can adapt to slight acid-base corrosion in industrial environments; Moreover, the failure rate is extremely low, with only the rotor and conical tube as the core components, which require almost no frequent maintenance and replacement, and have obvious cost control advantages.

What to note when measuring oxygen with a rotameter?

However, it should be noted that it is more suitable for measurement under stable working conditions. If there are severe pressure fluctuations or sudden changes in flow rate, the measurement accuracy will be affected to some extent. Therefore, it is more suitable for routine monitoring scenarios that do not require high dynamic response.

Vortex flow meter for oxygen flow meter

Vortex flow meter for O2 gas

How vortex flow meter measure O2 gas flow ？

Vortex flowmeter is belongs to the "main force" of high flow oxygen measurement, with the advantages of high precision and wide range. It utilizes the Karman vortex street phenomenon generated by the fluid flowing through the vortex generator, captures the vortex street frequency through sensors, and converts it into flow rate.

What are the advantages of using a vortex flowmeter for oxygen measurement?

• Vortex flow meter principle makes it stable under high flow conditions - the range can cover 10 cubic meters to thousands of cubic meters per hour, which can meet the high flow oxygen delivery monitoring needs of industrial scenarios such as large chemical plants and steel plants.
• It has high measurement accuracy, usually up to ± 1% FS, good repeatability, small data deviation under long-term operation, and is not affected by slight fluctuations in gas temperature and pressure.
• It can adapt to working conditions with high pressure (up to tens of bars or even higher) and high temperature (usually -40 degree C ~200 degree C), and has outstanding stability in complex industrial environments.
• Vortex flow meter sensor parts is with no moving parts, so it has low wear and tear, long service life when taking volumetric measurement of O2.
• Digital gas flow meter for O2: Vortex flow transmitters supports multiple output signals such as 4-20mA/pulse/frequency/MODBUS RTU and HART, making it easy to connect to the central control system for remote monitoring.
• Option with integral temperature and pressure compensation, which can directly see O2 temperature , pressure ,flow rate and total flow information from the digital display.

At present, there are three main types of mainstream oxygen flow meters, each with its own adaptation scenarios: thermal gas flow meters are suitable for measuring gaseous oxygen, especially for small and medium flow conditions, with fast response speed, low pressure loss, and easy installation and maintenance; The metal tube rotor flowmeter has a simple structure and moderate cost, suitable for measuring medium and low flow rates at room temperature and pressure, with intuitive readings and strong corrosion resistance; Vortex flowmeter is suitable for measuring high flow gaseous oxygen, with high accuracy, wide range, adaptability to high pressure and temperature conditions, and good stability.

How to measure the small oxygen flow rate such as 10 sccm ?

Ultra low flow O2 gas flow meter/flow controller

The measurement of small oxygen flow rate (such as 1 sccm, 10 sccm, 100sccm and so on) requires a balance between accuracy and control capability, and the preferred choice is a small thermal gas flowmeter and controller. This type of equipment uses the principle of thermal diffusion to achieve precise measurement by sensing the heat changes during gas flow. The range can be as low as 0~1L/h, and the measurement accuracy can reach ± 1% FS, which can meet the needs of laboratory, medical equipment, small reaction vessels and other scenarios. At the same time, the integrated flow controller can accurately directly achieve O2 gas flow regulation without the need for additional control modules, making it easy to operate. The device is compact in size, with low installation space requirements, and is suitable for narrow working conditions.

How to measure liquid oxygen (LOX) flow rate?

Cryogenic LOX flow measurement

Liquid oxygen has the characteristics of ultra-low temperature (about -183 degree C) and easy gasification. Conventional flow meters cannot withstand extreme low temperatures and require the use of specialized Coriolis flow meters. This type of flowmeter adopts the principle of mass flow measurement, which is not affected by temperature, pressure, and density changes, and can work stably in ultra-low temperature environments. Low temperature resistant stainless steel alloy should be selected as the material to avoid low-temperature brittle cracking; The structural design should have good insulation performance to prevent the influence of liquid oxygen vaporization on measurement;

At the same time, it is necessary to meet the oil-free cleaning standards, eliminate safety hazards, and be widely used in liquid oxygen storage, transportation, chemical, aerospace and other industries for liquid oxygen flow monitoring.

What technical parameters to check when choosing an oxygen flow meter?

In addition to the core functions, the selection should focus on checking the following parameters:

• The measurement range should cover the actual flow range used, users need to provide min flow ,normal flow and max flow to silverinstruments.com engineers to size the proper O2 flow sensor size , to avoid affecting accuracy if the range is too large or too small;
• The accuracy level is determined by flow meter principle , using range ,operation temperature and pressure , with industrial scenes ranging from ± 1.5% to ± 2.5%, and high-precision requirements ranging from ± 0.5% to ± 1%;
• The working pressure and temperature need to match the actual working conditions. The pressure resistance range of the equipment needs to be confirmed for gaseous oxygen measurement, and the low-temperature tolerance ability needs to be verified for liquid oxygen measurement;
• Prioritize 4-20mA/pulse or HART protocol for output signals to facilitate access to control systems;
• The material should be made of oxygen compatible materials such as 316L stainless steel to ensure safety and stability.