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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.
Radar (Radio Detection and Ranging) is a system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. It transmits a signal, bouncing off the target and returning to the radar system. By analyzing the reflected signal, the radar can determine various parameters about the target.
When discussing FMCW, we are talking about a specific type of radar signal. Here's how FMCW works:
The benefit of FMCW is that the frequency change provides a way to determine the range (distance to an object). There's a delay when the transmitted wave bounces off an object and returns. During this time, the transmitted wave's frequency has changed. By comparing the received wave's frequency to the current transmitted frequency, the radar system can determine how long it took for the wave to return and thus calculate the distance to the object.
FMCW radar is handy because it can be more compact, requires less peak transmit power (because it's continuous wave and not pulsed), and can provide range and speed information simultaneously.
"Open air" in the context of radar transmitters usually refers to systems that operate without waveguides or enclosed transmission mediums. Instead, they transmit their signals directly into the environment. These systems are used in various applications, including vehicle radars (like those used in adaptive cruise control or autonomous vehicles), weather radars, and more.
An open-air radar transmitter that uses FMCW is a radar system that transmits a continuous wave signal directly into the environment, modulating the signal's frequency over time. By analyzing the frequency shift of the returned signal relative to the transmitted signal, the radar can determine the range to the reflecting object. This technology is widely utilized due to its efficiency, compactness, and ability to provide detailed information about detected objects.
Drexelbrook's open-air radar products deliver exceptional resolution and accuracy tailored for demanding applications. These instruments harness FMCW (Frequency Modulated Continuous Wave) technology, ensuring a powerful signal at the measurement surface. This robustness guarantees optimal return signals, even when measuring agitated liquids.
A Drexelbrook radar level transmitter stands out as the optimal choice for applications that necessitate non-contact technology.
For more information about Drexelbrook level instruments in New England, contact Piping Specialties / PSI Controls. Call 800-223-1468 or visit https://psi-team.com.
The operation of industrial processes is a delicate balance of efficiency, safety, and maintenance. A crucial part of maintaining this balance is ensuring the smooth operation of material handling systems, which often employ chutes to transport bulk materials. One common complication these systems face is the problem of chute blockages or plugging, a critical issue that can lead to costly downtime, equipment damage, and potential safety hazards.
Plugged chute detection technologies mitigate these challenges, offering early detection and warning of chute blockages. However, the effectiveness of these technologies varies, and understanding their characteristics is essential for making an informed decision.
Plugged chute detection technologies fall into three broadly classified groups, mechanical, acoustic, and electromagnetic methods.
Mechanical systems, such as tilt switches and paddle wheel indicators, are simple and inexpensive but prone to mechanical failure and false alarms due to vibration or material buildup. They also require regular maintenance to function effectively.
Acoustic detectors, on the other hand, utilize microphones to listen for changes in the acoustic signature of material flow. While this can be an effective method, it is sensitive to environmental noise and requires sophisticated signal processing to distinguish between normal and blocked flow.
Electromagnetic methods include capacitive probes, microwave radar, and RF Admittance. These offer non-contact detection and are less prone to false alarms and mechanical failures—however, the material's properties, environmental conditions, and installation setup affect their performance and application.
After an extensive review of these technologies, RF Admittance emerges as the overall best selection for plugged chute detection for several reasons:
Reliability
RF Admittance technology uses a probe to measure changes in the dielectric constant (a property of materials that affects their response to an electric field) between the sensor and the chute wall. When the chute is clear, the admittance (the measure of how easily a circuit or device allows an electric current to pass) between the probe and chute wall will be at one level, and when the chute is blocked, the admittance will change significantly. This reliable detection method leads to fewer false alarms than mechanical and acoustic systems.
Resistance to Material Buildup
One of the significant advantages of RF Admittance technology is its resistance to material buildup on the probe. The technology uses a driven shield construction that ensures only the material near the active sensor affects the reading. This feature helps to eliminate the risk of false alarms due to material buildup, a common issue in other technologies.
Versatility
RF Admittance technology works with various materials, regardless of their conductive or non-conductive properties, making it a versatile solution in different industries handling multiple types of bulk materials.
The Drexelbrook Plugged Chute Detector consistently identifies whether material is flowing through chutes. If the material ceases to flow due to a blockage, an alarm from the flush-mounted capacitance sensing element will be triggered, prompting further necessary actions such as notifying an operator or shutting down a conveyor belt.
The Drexelbrook detector, also known as a blocked chute switch, reliably tracks the presence or absence of bulk solids material in chutes without compromising flow speed. This cost-effective device ensures the continuous flow of materials.
Its robust sensor design makes this point-level switch optimal for handling materials such as coal, wood chips, ores, and powders. Since it is flush mounted through a chute wall, there is no protrusion into the chute to hinder or obstruct material flow.
The point-level switch can automatically identify and disregard coatings, thus preventing false alarms. It features a universal power supply that auto-detects and adjusts to the input power source.
Unlike similar technologies, the point-level switch for detecting plugged chutes permits remote electronics installation at a convenient or safer location.
The dependable detection of plugged chutes ensures smooth plant operations and significantly reduces the chance of spills due to blockages.
Key Features:
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:
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.
Commonly, valves are operated with handwheels or levers, although some must be regularly opened, closed, or throttled. In certain conditions, it is not always practical to position valves manually; hence actuators are employed instead of hand wheels or levers.
An actuator is a mechanism that moves or regulates a device, such as a valve. Actuators decrease the requirement for people to operate each valve manually. Valves using actuators can remotely control valve position, particularly crucial in applications where valves open and close or modulate fast and precisely.
Pneumatic, hydraulic, and electrical actuators are the three fundamental types.
Actuators position valves in response to controller signals and can be positioned rapidly and precisely to accommodate frequent flow variations. The instrumentation systems that monitor and respond to fluctuations in plant processes include controllers. Controllers receive input from other instrumentation system components, compare that input to a setpoint, and provide a corrective signal to bring the process variable (such as temperature, pressure, level, or flow).
You have a control valve when actuators pair with flow-limiting or flow-regulating valves. Generally speaking, control valves automatically restrict flow to provide accurate flow to a process to maintain product quality and safety.
Control valves can be linear, where the stem moves the valve disk up and down like globe valves, or rotational. Rotary control valves include butterfly valves, which open or close with a 90-degree rotation. The pneumatic diaphragm and electric actuators are the most prevalent on linear and rotational control valves.
Some valves require long stem travel or substantial force to change position. A piston actuator's higher torque is preferable to diaphragm actuators in these situations. Examples of piston actuators are rack and pinion and scotch-yoke designs.
Single-acting piston actuators control the air pressure on one side of a piston, and with higher air pressure, the piston moves within the cylinder and turns the valve. The air on the opposite side of the piston exits the cylinder via an air vent. With decreased air pressure, the spring expands, causing the piston to move in the opposite direction.
If air pressure falls below a predetermined threshold or is lost, the spring will push the piston to the desired position, referred to as the "fail" position (open or closed).
A double-acting piston actuator lacks a spring and has air supply ports on both ends of the cylinder. Increasing air pressure to the supply port moves the valve in one direction. Higher pressure air entering from the opposite supply port pushes the valve in the opposite direction. Filling the cylinder with air and releasing air from the cylinder is regulated by a device known as a positioner.
Typically, the control of pneumatic actuators occurs from air signals from a controller. Some actuators react directly from a controller, for instance, a 3-15 PSI controller pneumatic output. Sometimes, a controller signal alone cannot counteract friction or fluid pressure. This situation requires a separate, higher-pressure air supply and modulating it with a pneumatic or electro-pneumatic positioner. These devices regulate a higher-pressure air supply to ensure that an actuator has enough torque to position a valve accurately. The positioner responds to a change in the controller's air, voltage, or current signal and proportions the higher pressure air to the actuator. Connecting the actuator stem to the positioner is a mechanical linkage. This mechanical connection is also known as a feedback connection. As the actuator stem moves up or down, or rotationally, the link likewise moves. The location of the connection informs the positioner when sufficient movement coincides with the controller's air signal. The controller's signal transmits to the positioner instead directly to the actuator, and the positioner regulates the air supply provided to the actuator.
Like other process components, actuators are prone to mechanical issues. Since actuator issues can negatively impact the operation of a process, it is essential to be able to recognize actuator issues when they occur. Frequently, an operator can notice an actuator fault by comparing the valve position indication to the position specified by the controller. For instance, if the position indicator shows the valve closed, but the flow indicator on the controller indicates that flow is still passing through the valve, the valve seat and disc are likely worn, enabling leakage through the valve.
Because there are so many different styles and designs of actuators, positioners, and valves and so many industrial applications, the combination possibility matrix is vast. You must discuss your application with a knowledgeable, experienced valve expert. The success of your project in terms of product quality, system cost, maintenance, and safety depends upon it.