Wednesday, October 26, 2016

Continuous Liquid Level Measurement Using Bubbler Method

bubbler or downpipe liquid level measurement schematic
Bubbler or Downpipe Liquid Level Measurement Schematic
Courtesy King-Gage
Measuring liquid level in a tank or vessel can be accomplished in a number of ways, all of which require some arrangement of instrumentation to either infer the liquid level through measurement of a related physical property, or directly deliver the liquid level visually using a scaled gauge arrangement. One indirect method of level measurement, referred to as the bubbler or downpipe method, is so named because it employs a purging gas that continually vents from the bottom of a dip tube extending into a tank of liquid. Through a simple apparatus, the level of a liquid can be inferred by the amount a back pressure exerted upon the gas flowing through the tube.

Probably the greatest advantage of this method of liquid level measurement is that the subject liquid does not contact the sensing instrumentation. The only portion of the apparatus in contact with the liquid is a tube immersed into the tank. Selecting the proper material for the immersed tube is left to the user. An additional feature of this method is the entry of the sensing tube from the top of the tank, eliminating the need for a fitting below the liquid level surface.

Basically, a purge gas flows through the immersion tube and may bubble out the immersed end of the tube, which is open to allow the contained liquid to exert a hydrostatic pressure on the purge gas. The back pressure on the gas that is exerted by the liquid contained within the tank will vary directly with the depth of the liquid. The back pressure can be correlated to a liquid level. Further calculations, which would include the tank shape, dimensions, and the liquid density can provide an indication of the volume and mass of the liquid.

It is possible for a user to assemble the components necessary to put a bubbler level indicator into operation, but King-Gage produces a device which consolidates purge control, pressure measurement, level signal transmitter, and necessary connections into a single compact device. There are versions of this level transmitter for electric and pneumatic output signals. They also include an additional level of protection in the form of an internal diaphragm that further isolates the device from the measured medium.

More details, along with some good illustrations, are provided in the document below. Share your process measurement challenges with application specialists, combining your process expertise with their product application knowledge to develop effective solutions.


Tuesday, October 18, 2016

Knowledge Base for Steam System Components

steam system schematic showing area of steam utilization
Steam utilization schematic showing array of products (blue)
Spirax Sarco
Steam, ubiquitous source of industrial power and commercial heat, ranks as a substantial continuing expense item for any organization where it is utilized or produced. Designing, installing, and managing steam system operation effectively can generate immense cost savings over less rigorous approaches.

An effective method of good decision making involves tapping into the experience and expertise of those that have gone before, accomplished what you plan to attempt. For steam systems, Spirax Sarco is a premiere source of information, knowledge, and expertise. The company has been deeply involved in the production and utilization of steam for many years, designing and manufacturing components utilized throughout the entire process.
steam system schematic showing components utilized in production of steam
Steam production schematic showing array of products (blue)
Spirax Sarco
In the steam generation section of an operation, the company provides a extensive array of interrelated products.
  • Blowdown Heat Recovery Systems
  • Blowdown Vessel
  • Boiler Feedtank Systems
  • Boiler Level Controls and Alarms
  • Bottom Blowdown Valves and Systems
  • Condensate Contamination Detection
  • Electrically Actuated Two Port Control Valves
  • Pipeline Strainers
  • Sample Coolers
  • Safety Valves
  • Spirax Range of Flowmeters
  • Steam Trap Performance Monitoring
  • Tank Level Controls
  • TDS Control
  • Vacuum Breakers
Throughout the balance of the steam system, the list of components available from the company expands even more, illustrating Spirax Sarco's depth of knowledge about steam system components and how they function together to deliver efficient and safe steam system operation.

Reach out to experts with your steam system challenges, combining your facility and process knowledge with their product application expertise to develop effective solutions.

Thursday, October 13, 2016

Stainless Steel Globe and Gate Valves For Industrial Process Control

stainless steel gate valve globe valve for industrial process control
Stainless Steel Gate Valve
CPE-Aloyco
Gate and globe valves see common usage throughout fluid processing industries. The correct procedure for valve selection includes an evaluation of the process media, environment, and how the valve will need to perform.

Gate valves, unless specially adapted, are intended for applications requiring only fully open or closed service. Their slow operation is advantageous at preventing hammering in the piping system and a fully open gate valve presents little pressure drop.

Globe valves are well suited for shutoff and throttling operation, controlling fluid flow at points between fully open or closed. The "Z" pattern of their fluid path does add some pressure drop.

Selecting the right valve construction material is an important element of a successful installation. Aloyco, a Crane brand, recommends consideration of several factors.
  • Type of media
  • Media temperature range
  • Pressure range, including all possible conditions
  • Environmental conditions which may affect the valve
  • Extraordinary stresses to which the valve may be subjected
  • Compliance with safety standards and/or piping codes
Stainless steel valve construction will provide an additional measure of corrosion resistance and may be a selection that extends the useful life of a valve.

More detail is included in the document included below. Share your fluid control requirements and challenges with a specialist, combining your process experience and knowledge with their product application expertise to develop effective solutions.



Thursday, October 6, 2016

Regenerative Turbine Pumps

regenerative turbine pump for industrial use
Regenerative Turbine Pump
Roth Pump
Most of us are familiar with centrifugal pumps and their generally understandable operating design. A regenerative turbine pump is significantly different in the way in which liquid moves through the impeller section, enabling this pump type to prove advantageous in a number of industrial applications.

A centrifugal impeller basically traps some liquid at the inlet and rapidly slings through the discharge port. The liquid velocity is increased by the impeller and manifests as outlet pressure. The key distinction here is that the liquid enters and exits the impeller only one time. A regenerative turbine pump has an impeller with a comparatively larger number of vanes, also of a different shape. This shape imparts a circulatory movement of the liquid from the vanes to the casing, and back to the vanes. Each return to the vane section increases fluid velocity, which can be converted to increased pressure. As the impeller rotates, liquid enters, leaves, then re-enters the vane section many times. This process is called regeneration. The impact of this design is a pump that can deliver substantially greater pressure than a centrifugal pump with the same impeller diameter and rotational speed.

A regenerative turbine pump is capable of pumping fluids with up to forty percent entrained gases without damage from cavitation or any performance loss. Fluid conditions with even low levels of entrained gases would likely produce substantial loss of performance in a centrifugal pump, evidenced as fluctuating discharge pressure and excessive wear and vibration. Where cavitation is a concern, the regenerative turbine pump holds the advantage over centrifugal. Applications with low flow and high head requirements will also be better serviced by a regenerative turbine pump.

There is more to be learned. Some additional detail and explanation are provided in the document included below. Effective solutions are developed through a combining of your process knowledge and the application expertise of a product specialist. Reach out and share your fluid transfer challenges for the best solution.