Using a continuous level sensor to monitor the bulk solid material level in your storage vessels can help you keep material flowing smoothly and prevent costly process interruptions. To help you choose the right continuous level sensor, please contact our bulk handling instrumental experts for instant advices.
A continuous level sensor measures the amount of material in a storage vessel on a continual basis, rather than just indicating whether the material is above or below a certain point, as point level sensors do. This makes a continuous level sensor ideal for monitoring material inventory in your vessels to prevent downtime. Depending on the sensor type and supplier, the continuous level sensor can output data to a console or panel, send the information to a PLC, HMI, or PC, or send the information to the Internet for anywhere, anytime access. An advanced system using multiple sensors can report data from multiple vessels at your site or from vessels at multiple sites, making it easy to monitor your entire operation's inventory status.
Types of continuous level sensors include weight‐and‐cable, 3D scanners, guided‐wave radar, open‐air radar, laser, and ultrasonic. Each type operates differently and has its advantages and disadvantages. Below we provide you some technical information about one of the most commonly used type - Open-air radar, for detecting bulk solids.
Open‐air radar 非接触雷达式
An open‐air radar sensor transmits a radio‐frequency signal to the material surface, which reflects a small portion of the signal back to the sensor's antenna. The sensor processes this returned signal to determine the material's level. The sensor's antenna is typically aimed at the vessel's discharge to prevent the signal from reflecting off the angled bottom when the vessel is nearly empty, which could cause false measurements.
Sensor models are available with different antenna types and operating frequencies (typically ranging from 6 GHz to 80 GHz). Which model will perform successfully in an application depends on the vessel height, the material being measured, the presence or absence of dust, and the sensor's operating frequency.
The sensor's measuring range varies depending on the operating frequency. Sensors with frequencies of 26 GHZ or less can measure up to about 100 feet (30m), while a 80 GHz sensor can measure almost 400 feet (122m). A 26 GHz radar measures in a 10° beam angle, while a 80 GHz radar measures in a very focused 4° beam angle that is ideal for precise targeting. All open‐air radar sensors measure the material level at a single point where the antenna is aimed.
Advantages of the open‐air radar sensor 非接触雷达料位计的优点
• Provides continuous level measurement
• Is nonintrusive and doesn't contact the material
• High frequency open‐air radar can be used in vessels up to 393 feet (~120m) tall
• Narrow beam can be precisely targeted to avoid structure
• Fast reaction/update time tracks filling or emptying activity
• Versatile for use in solids, liquids, and slurries
• Signal not affected by corrugation
• Is virtually unaffected by changes in process temperature, pressure, or material bulk density
Disadvantages of the open‐air radar sensor 非接触雷达料位计的缺点
• Measures a single location so cannot account for variances in topography
• Single point measurement will not result in highly accurate volume
• Doesn't work well with materials that have a low dielectric constant, which don't reflect much radar signal back to the sensor
• Must be carefully located and pointed to desired measurement location
• May require air purging, so a supply of compressed air would need to be run to the sensor
• Lower frequency models may not perform reliably in very dusty environments
• Can have a limited measuring range when the sensor is using a wide beam angle
• Is susceptible to false measurements in nearly empty cone‐bottomed vessels
• Tends to have a high purchase cost compared to the other sensors