Sunday, August 30, 2015

Fun Engineering Stuff from BCE - Static Fluid Dynamics

Many process control field devices measure pressure to determine other process variables, such as level and flow. Knowing basics principles of how process instruments work is important. Let's have a little fun with some basic fluid principles.

Question One

Suppose we were to steadily pour a liquid into the leftmost vertical tube until it reaches a mark four inches from the bottom. Given the diameters of the other tubes, how high will the liquid level settle in each when all columns are in a condition of equilibrium (no liquid flowing through any part of the system)?

Now consider the same set of vertical tubes (same diameters, same step heights) connected at the bottom by an inclined pipe. If we were to pour a liquid into the leftmost vertical tube until it reaches a mark two inches from its bottom, how high will the liquid level settle in each column when all columns are in a condition of equilibrium?

Question Two

Which of these tubes will generate the most hydrostatic pressure, assuming they all contain the same type of liquid at precisely the same (vertical) height?

(Attribution for questions to Tony R. Kuphaldt.)

Tuesday, August 25, 2015

Basic Operation and Function of Control Valves

control valve basics
Control Valve (Cashco)

Control valves are an integral part of many process control loops. Understanding their basic operation is important for any process control professional. Here is an excellent document outlining the control valve operation, the major components, and terminology used.

This document covers:
  • Terminology
  • Control Valve Basic Designs
  • Characterization and Trim Design
  • Control Valve Technical Considerations
  • Force-Balance Principle
  • Actuator Basic Designs
  • Control Valve Unit Action
  • Actuator Benchset Range
  • Valve Positioner Basics
  • Control Loop Action
  • Control Valve Packing Designs
  • Seat Leakage

Wednesday, August 19, 2015

Insertion and Inline Mass Flowmeters

inline - insertion mass flowmeter
Click image for larger view.
Need a flowmeter able to cover wide piping sizes from 1 1/2" piping and up, consider inline or insertion flowmeters. Constructed of 316 SS, with 2 RTD sensors, offering dual tip and single piece construction with no ports to clog. Thermal Instrument insertion probe mass flow meters provide reliable, accurate, and repeatable measurement of gas and liquids.

These mass flowmeters operate using a constant temperature system that employs two RTD sensors; one for sensing temperature, and one for sensing flow. The sensor is heated to a precise temperature above that of the fluid passing by. The fluid conducts heat off the sensor in direct proportion to the mass flow rate. The temperature is used to set the heat on the flow sensor and correct for changes in the fluid temperature.

The insertion meter is inserted directly into the flow stream to measure the flow rate of gases, liquids, or slurries in stacks, irregularly shaped lines, and process ducts. Unlike other probe flow meters, these devices have no apertures that can be clogged with particles or distorted by wear. Probes are manufactured using 316 SS as a standard, but corrosion resistant materials such as Hastelloy C, Monel, Inconel, Tantalum, and Carpenter 20 are also available. In addition, protective coatings are available including: Carbide, Fluorocarbon , Teflon, and Sulfinert.

Excellent for mass flow measurement for gas, mass flow measurement for water and other liquids, mass flow measurement of natural gas, landfill gas, oxygen, hydrogen, helium, and argon.

Friday, August 14, 2015

A Mini Electric Heater for Clean Flowing Gases

Need a small, compact electric heater to heat flowing air or gas? Equipment manufacturers and laboratory engineers  can find themselves challenged to provide a stream of clean high temperature air or gas.

The solution? A mini “process air” heater.

These heaters are designed so that the stream of air is heated by passing over an enclosed heated metal surface rather, than directly over resistance elements. This prevents contaminants from entering the flow of gas.

Generally, these heaters have the following specifications:
  • Designed for applications where streams of high temperature, clean air is needed. 
  • Air flow passes over an enclosed heated body; not exposed to ni-chrome  resistive elements.
  • Constructed of 304 Stainless Steel (other material is available). 
  • High temperatures, ranges and temperature sensors are available. 
Electric process air heaters provide quick heat up and cool down cycles with maximum heat transfer. They are compact and available in a variety of voltages.

There are many uses for these clean air process heaters. Some general applications are laminating, drying, baking, shrink fitting, plastic welding, soldering, preheating and metalworking, and packaging.

More specific industry uses are:

  • Combustion testing
  • Flow simulation
  • Component stressing
  • Curing adhesives
  • Fuel cell testing
  • Paperboard sealing
  • Heat shrink installations
  • Forming
  • Curing adhesives
  • Sterilizion
  • Pharmaceuticals
  • Medical/surgical hardware
  • Packaging materials
  • Speed drying
  • Activation adhesives 
  • Ink drying

  • Air knife in wave solder machines
  • Soldering/desoldering PC boards
  • Multi-station desoldering
  • Wafer and PC board drying
  • Heat shrinking insulation
  • Preheating process gases
  • Heat welding plastic or vinyl
For more information about these heaters, contact:

21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999

Thursday, August 13, 2015

Safety Instrumented Systems to Mitigate Risk of Combustion Process

combustion analyzer
Here is a paper by AMETEK Process Instruments presented at the ISA Analysis Division Symposium on mitigating risk (personnel injury and/or loss of production) of the combustion process through implementing Safety Instrumented Systems (SIS).

Safety Instrumented Systems identify hazardous operating conditions and correctly respond in such a way to bring the combustion process back to a safe operating condition or implement an automatically controlled shutdown to reduce the risk of operator error causing a catastrophic event.

For more information, contact:

21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999

Tuesday, August 4, 2015

Flue Gas Desulfurization (FGD) Slurry: Measuring Density

fluid gas desulfurization
Fluid Gas Desulfurization Using
Non-contact Gamma Density Gauge
courtesy of RONAN
(click to view larger)
Application Note courtesy of RONAN Measurements

Burning pulverized coal produces sulfur dioxide (S02) gas as a by-product. To reduce S02 emissions, wet scrubber flue gas desulfurization systems (FGD's) were installed in many power plants in response to the Clean Air Act of 1990.

Low cost, and highly available, limestone is used as a reagent in FGD's. The limestone slurry scrubs S02 from the flue gas, thus reducing its escape in to the atmosphere. The resulting by-product of this reaction is mixed with air and produces calcium sulfite, which is then filtered and de-watered and reused as ingredients for wall board, fertilizer or cement.


Accurately measuring and controlling the slurry density before and after the scrubbing process is difficult because limestone slurry is very abrasive and is very caustic. Because of this, density measurement with in-line gages becomes very difficult and expensive.


Using a non-contact gamma density gauge, mounted externally to the pipe, keeps the gauge separated from the slurry and protected from the abrasives and caustic chemicals present. Using a non-contact gamma density gauges also results in lower maintenance and lower costs as exotic wetted materials are not needed. Because in this approach, density is directly measured as a mass in a given volume, and not inferred as with other volumetric technologies (inferring density, the measurement is prone to errors because of varying process variables), the accuracy of non-contact gamma density gauges is very high. Finally, no sampling of the slurry is required, eliminating the need for bypass piping.


Radiometric Measurement provides accurate and reliable solution to measure slurry density, with low cost of ownership.

For more information, or if you have a challenging density measurement application, contact:

21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999