Showing posts with label level. Show all posts
Showing posts with label level. Show all posts

Monday, September 11, 2017

Industrial Level Measurement

Point level
Point level switch (FCI)
In many industrial processes, the measurement of level is critical. Depending on the nature of the material being measured, this can be a simple or complex task. Several different technologies for sensing level are briefly explained here.

Direct Method

The direct method of level measurement calculates levels instantly using physical properties, like buoyancy and fluid motion. Beginning from the simplest, the following are the three main types:
  • Sight glass type
  • Float type
  • Magnetic level gauge
Sight glass measures liquid in tanks. A scaled glass tube with metallic covering it is attached to the top and bottom edges of the tank and, as the liquid moves up and down, the level in the tube fluctuates in the same way.

Float type measurement makes use of buoyancy: a float device follows the liquid level while sitting atop it. As the liquid moves so does the float device; a cable, attached to the top of the device, is rigged to a calibrated scale with a pointer in the middle. The up and down movements pull the string which pulls the pointer, thus showing where the liquid level is.

 A magnetic level gauge looks like a thick thermometer and is attached to the end of a vertical chamber. This vertical chamber contains a magnetic float, a permanent magnet, which floats on the top of the liquid level in the tank.

There is one more thing also attached to the outside of the tank: an indicating scale with small metallic strips. These strips are white and red sided flippers, rotating 180° whenever the float magnet attracts them while passing over. Whenever the float magnet is above, the strips will flip red side up, indicating the tank’s level.

Indirect Method

In the indirect method of level measurement, the level of a liquid is calculated by a variable that changes according to the level. There are four main types:

  • Pressure gauge type
  • Differential pressure type
  • Ultrasonic type
  • Radar type
The pressure gauge is a simple method; a pressure gauge is attached near the bottom of tank and pressure, exerted by the tank, is calculated. The gauge changes in time with the tank’s liquid pressure, and the measurement is made according to the height of the liquid.

Radiometric Level
Radiometric Level (RONAN)
The differential pressure method (DP method) is another widely used method in industry. This method requires a DP transmitter and a port; these two parts are connected to the external tank at opposite ends. The differential pressure in the tank is measured between the DP transmitter at the bottom and the port at the top; the output of the differential pressure calculated by the DP transmitter is proportional to the liquid level. The more liquid in the tank, the more pressure is at the transmitter; the less liquid in the tank, the more pressure at the port.

The ultrasonic method is a no-contact type. A transmitter is mounted atop the tank and ultrasonic sound waves are sent from the transmitter toward the surface of the measured fluid. An echo of the wave is calculated and the time it took for the wave to reach its end goal from the transmitter becomes its distance. The time of the length of the distance is then calibrated in terms of the level of process material.

The radar method is a no-contact type and it uses electromagnetic waves. Electromagnetic waves are sent through a transmitter to the surface of the measured material. There is a receiver toward the bottom of the tank which takes a portion of the energy sent from the wave and then reflects it back toward the surface of the medium. The reflected energy then becomes calibrated into level measurement.

Industrial level control requires deep knowledge and understanding of many process variables, such as media compatibility, interfaces, head pressures, material densities, and mechanical considerations. It's always recommended that an experienced consultant be involved with the selection and implementation of any industrial level device.

Thursday, December 15, 2016

Versatile Thermal Dispersion Switches For Level, Temperature, Liquid Interface, and Flow Applications

flow level interface temperature switch for fluid process control
Sanitary version of  FLT93 FlexSwitch
Courtesy Fluid Components International
Thermal dispersion, as a method of process measurement, relies upon precise temperature measurement and, in some cases, the ability to measure heat input. The principal is fairly simple, based upon the relationship between two temperature measurement points in the subject fluid. One is heated by the control system in a known manner, the other is not. Whether measuring fluid flow, or functioning as a liquid level or interface switch, the relationship between the two temperature measurements can provide the needed information reliably, accurately, and without any moving parts in the measurement system.

Fluid Components International utilizes these physical principals in the operation of their FlexSwitch line of thermal dispersion measuring instruments. By combining modular components in various ways, the company offers switches suitable for applications across a wide range of industries.

  • Flow
  • Level
  • Flow and temperature
  • Level and temperature

Features throughout the product line include:

  • Dual trip points and relays
  • SIL 2 rated, ultra reliable
  • 3 year warranty
  • Broad agency approvals
  • Suitable for full range of pipe sizes
  • Apply in fluids to 850 °F (454 °C)
  • No moving parts to foul, clog or maintain
  • All welded elements
  • Easy to install and set-up
  • Highly sensitive and accurate
  • Threaded, flanged, packing gland installation
  • Integral or remote mounted electronics
  • Choice of enclosures
  • Field selectable AC or DC power
More information about the FlexSwitch line of thermal dispersion based switches is provided in the document below. For best results, share your project requirements and challenges with a product application specialist. Combine your process knowledge with their product application experience and develop effective solutions.



Tuesday, August 9, 2016

Non-contact, Radiometric Level Detection for Liquids or Solids

Radiometric level detection
Radiometric level detection
(courtesy of RONAN)
Radiometric level detection, using a very low gamma level source, is designed to deliver outstanding performance in a wide range of difficult applications and process conditions for both liquids and bulk solids which include the most dangerous materials such as caustic, toxic, corrosive, explosive, and carcinogenic irrespective of their viscosity and temperature.

These level gauges meet “As-Low-As-Reasonably-Achievable” (ALARA) guidelines. Source activity is customized depending on vessel and process parameters such as diameter, wall thickness, material, and measurement span to ensure optimum sensitivity, economy and safety while keeping the source activity to a minimum.

An exclusive “Radiation Low Level” (RLL) source holder uses up to 100 times less gamma energy than comparable gauges, and is the only source holder recognized by the NRC to be so safe that it does not require the stringent documentation, training or handling procedures of other systems.

How it Works

Radiometric level detection
Sources and Detector Mounted
External to Vessel 
Radiometric level measurement provides a safe and efficient, non-contact method to measure liquids or solids in harsh process environments. Each system consists of a gamma source, detector and microprocessor.
  • The gamma source, typically mounted external to the vessel emits energy through the vessel walls collimated in a direction towards the detector mounted on the opposite side of the vessel. The gamma energy reaches the detector when the vessel is empty. As the process level rises in the vessel, the gamma energy reaching the detector will decrease in an inversely proportional relationship to the level. 
  • The detector measures the level of energy and sends a proportional signal to the microprocessor. 
  • The microprocessor linearizes, filters, and correlates this signal to a level measurement. 
The entire system is mounted external to the vessel and can be easily installed and maintained while the process is running ... without expensive down time, vessel modifications or chance of accidental release.

Applications
Radiometric level detection
Low Level Source and Detector
Mounted External to Vessel

  • Solids or Liquid Measurement 
  • Measurement Not Affected by: 
  • Internal Obstructions. i.e. Agitators Extreme Process Temperatures 
  • Caustic Processes 
  • Violent Product Flow 
  • Sterile Process 
  • Changing Process 
  • Variable Product Flow 
  • Automatic Compensation for Vapor Density Changes 
  • Automatic Compensation for Foam or Gasses 
  • Automatic Compensation for Process Build-Up 
  • Detectors Contoured to the Shape of Vessels 
  • Upgrade Utilizing Existing Sources 
Features and Benefits
  • Accurately Measures the Most Complex Processes 
  • Solid Crystal or Flexible Scintillating Fill- Fluid 
  • Excellent Measurement Reliability due to Proprietary Filtering Technology 
  • Level Detection of Multiple Interfaces 
  • Low Maintenance / No Component Wear 
  • Auto-Calibration
For more information in Maryland or Virginia, contact:
Flow-Tech
410-666-3200 MD
804-752-3450 VA

Monday, October 19, 2015

Welcome to Flow-Tech's Maryland & Virginia's Process Control Blog

Virginia and Maryland Process Control
Serving Maryland and Virginia
Flow-Tech, Inc. has been specifying and applying process instrumentation and control valves in the Maryland and Virginia markets for over 40 years. Flow-Tech's outstanding growth in sales and reputation is directly a result of our consultative sales approach, delivered by our team of knowledgeable and experienced Sales Engineers.

We see this blog as an extension of that process where today's customer can learn and discover at their own time and place, narrow the selection of products and vendors, and then  arrange for me focussed presentation with a salesperson.

This blog will be populated with post we think you will find interesting and education in the area of process instrumentation and control. It will be updated frequently, so please check back often.