Piping Specialties Inc. (PSI) is one of the northeast's largest suppliers of valves; process controls/instrumentation, and engineered mechanical specialties. Industries served: Power Generation, Pulp/Paper, HVAC, Water/Wastewater, Food/Beverage, Life Sciences, Chemical/ Process, Semiconductor. For more information visit PSI-Team.com or call 800-223-1468.
The Level Measurement Company That Industrial Engineers Trust When It Really Matters
Level Measurement in the Food Processing Industry
Level sensors and controls are crucial in industrial food processing and production facilities to ensure quality and consistency. These devices monitor and regulate the level of liquids, solids, or granular materials in containers, vessels, or silos. Here are some of the most common types of level sensors and controls used in the industry:
- Capacitive level sensors: These sensors detect changes in capacitance caused by the presence or absence of material (liquid or solid) in a container. They measure liquids, powders, or granular materials levels in various applications, including food and beverages.
- Ultrasonic level sensors: Ultrasonic sensors use sound waves to measure the distance between the sensor and the material's surface. These sensors are non-contact and used for measuring levels of liquids or solids in tanks or silos and provide the food industry with accuracy and reliability.
- Radar level sensors: Similar to ultrasonic sensors, radar level sensors use radio waves to measure the distance between the sensor and the material's surface. They are also non-contact and suitable for liquid and solid materials. Radar sensors are particularly useful in challenging environments with dust, vapor, or foam, making them ideal for food processing applications.
- Hydrostatic pressure level sensors: These sensors measure the pressure exerted by the liquid column on the sensor at a specific depth. The pressure re-calibrates to a level measurement. They are primarily used for measuring liquid levels in tanks and have broad use in the food and beverage industry.
- Float level sensors: Float sensors use a floating device to detect the liquid level in a container. The float's vertical or tilting movement triggers a mechanical or electrical signal indicating the liquid level. Food processing plants often use them for simple and cost-effective level measurements.
- Vibrating or tuning fork level sensors: These sensors use a vibrating probe or tuning fork that changes its vibration frequency when it comes into contact with a material. They can detect the presence or absence of material and provide point-level detection of liquids, powders, or granular materials.
- Optical level sensors: Optical sensors use infrared or visible light to detect the presence or absence of a material at a specific level. They are suitable for various materials, including liquids, powders, and solids, in food processing applications where minimum contact with the material is essential.
The choice of level sensor and control system depends on factors like the process material, the required accuracy, the process conditions, and the specific application within the food processing facility. Each technology has advantages and limitations, so careful consideration is needed to select the most suitable option for each application.
SIL Level Switch Is Specifically Designed for Floating Roof Tanks
- Loop or Line Powered
- Wetted Parts: 316SS 3/4" NPT Mounting, 3/16" FEP insulated flexible and adjustable cable, non-sparking brass sensor.
- Automatic and local or remote manual test functions ensure proper system operation.
- One system fits most floating roof tank applications, reducing field spans
- Adjustable insertion lengths up to 15' (4,6m)
- Excellent trip point accuracy over a wide range of medias and tank roof
Industrial Thermowell Process Connection Types
Water Cut Meters from Drexelbrook
Water cut meters measure the water cut (or BS&W) of oil flowing from a well, a separator, crude oil transfer in pipelines, and tanker loading.
Food Industry Batch Level Control
- 3A designed sanitary sensing elements
- No moving parts
- 3 control points on one vertical sensing element
- Cote-Shield circuitry eliminates false alarms due to coatings
- Designed to endure Clean In Place (CIP) demands
Level Measurement Solutions for Water Treatment
Several functional level measurement technologies have viable solutions for a broad range of industrial and municipal water treatment applications. Because of the variety of applications that exist and the varying application conditions, no one technology is best suited in all cases.
POINT LEVEL VERSUS CONTINUOUS LEVEL INSTRUMENTS
Regardless of the application, there are two significant classifications of level measurement instrumentation: point level and continuous level measurement.
Point Level (On/Off) measurement indicates the absence or presence of level at a certain threshold (point) within a vessel. Point-level switches perform as high level and spill prevention alarms, low level, pump protection alarms and pump control.
Continuous Level (Proportional) measurement indicates the level in a vessel over the full span of capacity. These devices perform as process control as well as inventory control and management.
LEVEL CONTROL TECHNOLOGY CHOICES
The technologies used to measure level are affected differently by the varying process conditions. Below is a brief description of the different technologies commonly used in a water treatment facility.
RF ADMITTANCE/CAPACITANCE
RF Admittance/Capacitance employs a radio frequency signal and monitors for a change in capacitance. Either the presence or absence of material or how much material is in contact with the sensor, making it highly versatile and a right choice for a wide range of conditions and materials for point or continuous level measurement.
RADAR
Radar utilizes either Pulsed Wave or Frequency Modulated Continuous Wave (FMCW) through-air transmission that allows for an accurate non-contact reading of reflected electromagnetic signals.
MAGNETOSTRICTIVE
Magnetostrictive uses an electric pulse from ferromagnetic wire to accurately detect a float's position with embedded magnets. As the pulse intersects the float's magnetic field, a second pulse reflects an electric circuit that accurately determines the distance and thus the level position.
CONDUCTIVITY SWITCHES
Conductivity switches measure the drop-in resistance when a conductive liquid contacts with two probes or a probe and a vessel wall.
ULTRASONIC (POINT LEVEL)
Ultrasonic (Point Level) measurement electronically resonates a crystal at a fixed frequency to generate sound waves that travel across an air gap to a second crystal. As liquid fills the gap between the two crystals, the second crystal begins to resonate with the first.
ULTRASONIC (CONTINUOUS LEVEL)
Ultrasonic (Continuous Level) measurement uses a transmitter to generate an ultrasonic pulse and measures the time it takes for a reflected signal to return to the transducer to determine a liquid level.
GUIDED WAVE RADAR (GWR)
Guided Wave Radar (GWR) utilizes a Time Domain Reflectometry (TDR) technique by sending a highly focused electronic signal down a metallic rod or flexible cable waveguide. When the transmitted signal intersects the liquid's surface, it reflects along the rod or cable to determine the distance traveled. The level position is then easily inferred.
HYDROSTATIC
Hydrostatic measurement immerses a pressure transmitter with a sensing diaphragm and a sealed electronic circuitry that transmits an analog signal proportional to the liquid level above the sensor.
FLOAT SWITCHES
Float switches rely on a low-density float mounted in a vessel that magnetically couples to a limit switch. A change in fluid height actuates a switch by moving the float.
VIBRATION/TUNING FORK
The Vibration/Tuning fork is piezoelectrically energized and vibrates at a frequency of approximately 1200Hz, and as the process media cover the fork, the frequency shifts. The internal oscillator the frequency shift by and converts it into a switching command.
POINT LEVEL SOLUTIONS
Advanced RF Admittance/Capacitance point level devices are the most versatile of the point level technologies, especially with process media that can coat the sensor. They provide excellent spill/overfill protection. They are simple to install and have no moving parts, making them virtually maintenance-free. Their robust design and circuitry make them an ideal solution for many water treatment applications.
Both tuning forks and ultrasonic gap switches provide reliable high- or low-level measurements in various applications. For non-coating conductive liquids, conductivity switches provide economic priced measurement while float switches appear in many basic applications at very cost-effective prices.
CONTINUOUS LEVEL SOLUTIONS
Mechanical systems such as floats and bubblers require extensive maintenance and are less reliable and accurate than electronic systems. Hydrostatic systems afford better reliability and are simple to use, and can transmit data to another receiver for remote monitoring, recording, and control.
RF Admittance/Capacitance level is a time-proven and one of the best available technologies for indication and control. RF technology inherently provides the highest accuracy and repeatability in interface measurements. Variations in the makeup of upper and lower phases of a liquid have no appreciable effect on system accuracy. Recalibration is not required.
For short-span measurements, RF Admittance technology provides one of the most preferred readings. As the level of measurement span decreases, the more appropriate RF technology becomes. In spans of only a few inches, RF systems can repeatedly produce accuracies of 1/32ths of an inch. RF has the added benefit of not being limited by “dead zones” inherent with many popular technologies often selected for measurement ranges larger than 5 feet.
Non-metallic tanks pose no technical problems for Ultrasonic, Magnetostrictive, Hydrostatic Pressure, Radar, and GWR (Guided Wave Radar) technologies. The GWR approach is suitable for vessels with internal obstructions and uses lower energy levels than airborne radar technologies. Non-contact technologies, such as Radar and Ultrasonic, can have measurement ranges up to 130 feet.
For long-range measurements or headroom limitations, flexible sensors offer insertion lengths up to several hundred feet for Hydrostatic Pressure and RF Admittance technology products. Loop-powered GWR (TDR)-based products allow measurement ranges up to 115 feet in selected applications. Magnetostrictive technology provides an accuracy of 0.1% of measurement span in flexible sensor designs up to a maximum range of 70 feet.




