Flow Sensors / Flow Meters
A flow sensor/meter for liquid and gas. KEYENCE has developed various clamp-on types to enable stable flow rate measurement with no pipe modification. These devices can be used on small tubes to large pipes. The lineup also includes electromagnetic and Coriolis flow sensors as well as environmental resistant and sanitary types.
Liquid flow rate
Compatible with a variety of pipe materials and liquids, the FD-Q Series Clamp-on Flow Sensor can detect the flow rate of a liquid without the need for any pipe modification. This device enables the detection of a wide variety of liquids, including water (and pure water), oil, and chemicals. Detection is possible on both metal and resin pipes up to 2" in diameter. Unlike conventional sensors, installation and operation are also easy on high-pressure pipes. Costs are significantly reduced with the minimal installation required and the completely non-wetted design eliminates the risk of pressure loss or increased maintenance. Additionally, the large indicator provides real-time status information.
The FD-X Series Clamp-on Micro Flow Sensor can be easily installed from outside the pipe and detect flow rates as low as 0.1 mL/min (and shot amounts as low as 0.001 mL). The device does not come into contact with the liquid, preventing problems such as pressure loss and clogging. The non-contact design also means the device is not affected by the properties of the liquid (ex. viscosity). Even coating/filling applications of grease, adhesives, flux, sealants, chemicals, and other liquids are possible with the FD-X series. The design also prevents pressure drops, enabling flow rate measurement with no adverse effects on equipment conditions, such as jetting and spraying functions. Also, this clamp-on technology means there is no pipe cutting or modification required.
KEYENCE's FD-R Series Clamp-on Flow Meter is designed for pipes as large as 8". Installation is easy and requires only a screwdriver. The device can be mounted to a variety of materials including stainless steel, iron, copper, PVC, and resin. Both flow and temperature monitoring is possible for a wide variety of liquids—from water (including pure water) to oil, chemicals, and high-pressure liquids—at temperatures between -4°F and +248°F. The device does not come into contact with the liquid, so there is no risk of liquid-based corrosion or degradation, reducing maintenance time and costs. The rugged metal construction includes an easy-to-read indicator light, and data can be recorded directly on the device. The IP69K enclosure rating and NEMA4X compliance make this sensor both highly reliable and convenient for indoor and outdoor use.
The FD-M Series Non-Wetted Electrode Electromagnetic Flow Sensor is the first factory automation flow sensor to adopt a free-flowing structure. Unlike floating-element and paddlewheel devices, the free-flowing structure of the FD-M Series has no moving parts or obstructions in the flow pipe, greatly reducing the risk of clogging. With no moving parts, the sensor is not subject to mechanical wear, which ensures a long service life. There is also virtually no pressure loss in the pipe, so the pump uses even less energy. Unlike conventional electromagnetic systems, this device detects liquid from outside the pipe, making it highly resistant to insulating deposits inside the pipe while minimizing maintenance. Two sensor types are available: one with a separate amplifier that allows flow rate monitoring using the LEDs on the sensor head and one with an integrated amplifier and a dual-row digital display for easy setup.
Gas flow rate
The FD-G Series Clamp-on Gas Flow Meter can be easily installed from outside the pipe with only a screwdriver. The clamp-on design greatly reduces installation costs by eliminating the need for pipe modification. Detecting flow from outside the pipe eliminates the risk of restricting or blocking the flow of gas. It also eliminates the risk of leakage from new fittings. The device is compatible with stainless steel and iron pipes from—3/4" to 8"—and can measure compressed air, nitrogen, and other gases. The high-accuracy measurement, paired with a minimum sensitivity of 0.018 CFM, can be utilized for both large flows and incredibly small leaks. The high-definition display can also show both the total flow rate and the current flow rate for a set period, at the same time. Necessary functions for air management are also included, such as automatic leak volume measurement and monetary conversion.
Flow meters, also known as flow sensors, are used to measure the flow rate of a liquid or gas. There are a variety of different types of flow meters, including ultrasonic, electromagnetic, Karman vortex, paddlewheel, floating element, thermal, and diaphragm types. Flow meters that require no moving parts in contact with the target liquid are particularly effective in avoiding potential problems. For example, ultrasonic meters—also known as clamp-on systems—can be installed from outside the pipe for completely non-wetted measurement, preventing any risk of adverse effects on the liquid and eliminating the need for piping work. Electromagnetic meters detect flow via electromotive force created through electromagnetic induction. Models that use an electrode outside the water outlet are most effective. Meters that use the Coriolis method measure the backward force created by the flow of liquid through an oscillating U-shaped pipe. Alternatively, thermal meters measure the flow rate by looking at the amount of heat the liquid removes from a heating element.
Benefits of Flow Sensors / Flow Meters
The manufacturing of products can involve a wide variety of liquids. To ensure quality control, the liquid is monitored using a flow meter and then managed/analyzed accordingly to improve or stabilize product quality.
Using a flow meter for managing liquid flow enables data acquisition for alarms, diagnosis, and analysis. It also allows for management of minute flow rates such as equipment discharge and spray volumes, and management of air, nitrogen, or argon gas supplies based on instantaneous and total flow rates. Flow meters equipped with an analog output can respond flexibly to control and manage needs by transmitting alarm output and diagnostic/analysis data to a PLC or PC. Clamp-on flow meters, which use non-wetted methods that do not adversely affect the liquid, are also capable of measuring very low flow rates at high speeds. This is often necessary for controlling release agent, disinfectant alcohol, and flux application amounts. Mass flow sensors are not easily affected by temperature or pressure, making them suitable for the management of gases.
Flow control using a flow meter enables both predictive maintenance and superior device protection, such as when an optimum temperature range is specified or a correct amount must be used for cooling water circulation. Flow control makes it possible to prevent any deterioration in quality or malfunctions with equipment due to improper cooling.
Quick detection of a decrease in flow rate makes it possible to immediately perform predictive maintenance to avoid adverse effects on production or equipment. This means flow control using a flow meter is essential. A flow meter with two outputs enables the output of both a predictive alarm and the main alarm for proper maintenance before jigs or equipment becomes damaged. Monitoring the conditions of filters and strainers is also important for detecting clogs that may reduce flow. In other cases, bent or clogged pipes may not show a change in pressure, only a decrease in the flow rate. Using a flow meter in addition to a pressure sensor makes it possible to detect problems in the piping quickly for immediate response.
Manufacturing sites often use argon gas for welding, nitrogen gas for oxidation-prevention and heat treatment, and various other resources such as hydraulic oil and coolant. Using a flow meter for flow control makes it possible to visualize the amounts of resources used and to conserve energy (which reduces costs).
Flow meters capable of managing instantaneous and total flow rates simultaneously can detect abnormal flows. These devices can also gather data to determine possible reductions in the consumption amounts based on per-hour usage. Also, if the flow meter has no moving internal components, reductions in pressure due to clogging or other problems can be eliminated, contributing to greater energy conservation with no unnecessary load on pumps. Clamp-on flow meters can also be installed without having to cut piping, eliminating the risk of liquid and air leakages due to added pipe seams.
Flow Sensor / Flow Meter Case Studies
Equipment requiring liquid management (coolant, cleaning fluid)
Equipment requiring liquid management and flow monitoring include injection molding machines (mold coolant flow control), die-casting machines (coolant and mold release agent flow control), grinding machines and cutting machines (coolant flow control), sputtering systems (coolant flow control), and spot welding machines (coolant flow control). Using an applicable flow meter or flow sensor for flow management stabilizes product quality and prevents potential problems with equipment.
Equipment requiring liquid management (oil, coating solutions, chemical solutions, etc.)
Because liquid flow rates and process management are closely intertwined, flow meters and flow sensors are also useful in controlling the flow of liquids other than coolant and cleaning fluid. For example, flow control is also necessary with high-frequency quenching equipment (quenching fluid flow control), lapping/polishing/CMP equipment (slurry), dispensing equipment (flux, hot-melt, ink, grease, adhesives, painting solutions, coating agents, resist solutions, mold release agents, etc.), precision presses (lubricant, etc.), two-component mixers (pre- and post-curing agent liquids, water, printing paint, chemicals, emulsions, adhesives, etc.), cutting machines (for checking cutting oil amounts, etc.), concrete mixers and manufacturing equipment (water volume being mixed with materials), and flue gas neutralization equipment (water and chemical solutions used during smoke evacuation).
Equipment requiring gas flow control (nitrogen, oxygen, air, etc.)
Flow meters and flow sensors are used in processes and machines requiring the flow control of gases such as nitrogen, oxygen, and air. This includes reflow furnaces (nitrogen (N2) flow control to prevent oxidation), quenching furnaces (nitrogen (N2) supply control to prevent oxidation), chip component conveyors (for checking airflow during chip component absorption), electronic component packages (management of enclosed gas (nitrogen) to prevent oxidation), ionizers (air purge flow control), and painting robots (paint (liquid) and air (gas) management).
Frequently Asked Questions About Flow Sensors / Flow Meters
Air bubbles can enter the pipe with the liquid or be formed in the pipe due to impurities or other factors. Bubbles can cause Karman vortices to occur in vortex flow meters, and ultrasonic wave propagation can be obstructed in conventional ultrasonic flow meters, causing the flow meter to malfunction. Generally speaking, flow rates can be measured with no effects from air bubbles when using a meter that measures using the Coriolis method. In recent years, ultrasonic wave flow meters have also begun using stronger ultrasonic signals to ensure adequate signal propagation, even if bubbles are generated. Some ultrasonic flow meters are also able to cancel out the effects of air bubbles or to generate an alarm if air bubbles are detected.
For flow meters that use a standard wetted electrode, insulating deposits inside the pipe can make measurement impossible. Conventional electromagnetic flow meters are also prone to such problems. Flow meters that use capacitive detection with electrodes on the outside of the pipe are effective at preventing these kinds of adverse effects. Fully penetrating electromagnetic flow meters detect liquid from outside the pipe, allowing for stable detection even if the pipe is covered with insulating deposits. Naturally, badly contaminated pipes will require cleaning or other maintenance because of the potential adverse effects on the equipment.
The effects of frequent bending, branching, or diameter variations can result in an uneven velocity of flow in the liquid. This may result in significant measurement errors. To ensure a uniform velocity distribution, a straight section of a sufficient length must be provided on the upstream side of the flow meter or flow sensor. This straight section should be at least 5 times longer than the diameter of the flow path, or 20 times longer if severe deflections or swirling currents exist. If significant measurement errors still exist, consider installing a valve or aperture.
As liquid flows through piping, valves are opened/closed and as connected pumps and other equipment operate, vibrations can be generated. Such vibrations and other noise can result in measurement errors. Karman vortex-type and Coriolis-method devices are often affected by vibrations and are likely to suffer from incorrect measurements. Electromagnetic and ultrasonic devices, however, are virtually unaffected by vibrations. In particular, ultrasonic flow meters that are capable of transmitting and receiving ultrasonic waves at high frequencies are less susceptible to vibrations and noise to ensure stable flow measurement.
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