Saturday, November 11, 2017

Clamp-on, Transit-time Difference Ultrasonic Flowmeters Ideal for HVAC Retrofit and New Construction

Transit-time Difference Ultrasonic Flowmeters
Transit-time Difference Ultrasonic Flowmeters (Flexim)
There are many reasons for large commercial buildings, medical centers, museums, airports, sports complexes, federal institutions and military complexes to invest in building energy optimization efforts. Better and more efficient operation of HVAC equipment can reduce the buildings energy and operational costs significantly.

Controlling flow, temperature and pumps can provide energy cost savings of over 20%. Many campus energy managers believe that the biggest user of energy in any complex is the HVAC system, and the key to saving energy in HVAC systems is an accurate and reliable flow metering capability.

Better efficiency of the heating and cooling infrastructure of a building also leads to more environmentally friendly buildings, something that has become a social prerogative of building owners and operators.  Older buildings were not built with BTU meters as metering requirements were added to buildings through increased regulations.

Submetering the buildings heating and cooling systems have become increasingly more important, as building owners are both mandated to meter these utilities and have a financial interest in the accuracy of these BTU measurements. The problem historically is that nearly all flow meters are designed for gradual failure due to direct contact with the fluids they are monitoring and the particulate accumulation on the sensors.

Clamp-on, transit-time difference ultrasonic flowmeters are the ideal retro-fit flowmeter, and also should receive strong consideration for new building construction. Transit-time difference ultrasonic clamp on flowmeters exploit the fact that the transmission speed of an ultrasonic signal depends on the flow velocity of the carrier medium - kind of like a swimmer swimming against the current. The signal moves slower against the flow than with it.

How Transit-time Difference Ultrasonic Flowmeters Work

The flowmeter sends ultrasonic pulses through the process medium - one in the same direction as the
flow and one in the opposite direction. The flowmeter's transducers alternate as emitters and receivers. The transit time of the signal going with the flow is shorter than the one going against. The flowmeter measures transit-time difference and determines the average flow velocity of the process medium. Since ultrasonic signals propagate in solids, the flowmeter can be conveniently mounted directly on the pipe and measure flow non-invasively.

Contact Flow-Tech with your questions about any flow measurement application. Reach them at 410-666-3200, or visit

Tuesday, October 31, 2017

Understanding HART Protocol

A current loop using sensing and
control transmission with HART protocol
overlaid on the 4–20 mA loop.
The Highway Addressable Remote Transducer Protocol, also known as HART, is a communications protocol which ranks high in popularity among industry standards for process measurement and control connectivity. HART combines analog and digital technology to function as an automation protocol.

A primary reason for the primacy of HART in the process control industry is the fact that it functions in tandem with the long standing and ubiquitous process industry standard 4-20 mA current loops.

The 4-20 mA loops are simple in both construction and functionality, and the HART protocol couples with their technology to maintain communication between controllers and industry devices. PID controllers, SCADA systems, and programmable logic controllers all utilize HART in conjunction with 4-20 mA loops.

HART instruments have the capacity to perform in two main modes of operation: point to point, also known as analog/digital mode, and multi-drop mode. The point to point mode joins digital signals with the aforementioned 4-20 mA current loop in order to serve as signal protocols between the controller and a specific measuring instrument. The polling address of the instrument in question is designated with the number ì0î. A signal specified by the user is designated as the 4-20 mA signal, and then other signals are overlaid on the 4-20 mA signal. A common example is an indication of pressure being sent as a 4-20 mA signal to represent a range of pressures; temperature, another common process control variable, can also be sent digitally using the same wires. In point to point, HART’s digital instrumentation functions as a sort of digital current loop interface, allowing for use over moderate distances.

HART in multi-drop mode differs from point to point. In multi-drop mode, the analog loop current is given a fixed designation of 4 mA and multiple instruments can participate in a single signal loop. Each one of the instruments participating in the signal loop need to have their own unique address.

Image courtesy of  Dougsim (Own work) [CC BY-SA 4.0], via Wikimedia Commons

Tuesday, October 24, 2017

Vibration Analysis in Manufacturing and Process Control

Vibration graph
Image courtesy of Wikipedia
As all of us who ride or drive an automobile with some regularity know, certain mechanical faults or problems produce symptoms that can be detected by our sense of feel. Vibrations felt in the steering wheel can be an indicator of an out-of-balance wheel or looseness in the steering linkage. Transmission gear problems can be felt on the shift linkage. Looseness in exhaust system components can sometimes be felt as vibrations in the floorboard. The common thread with all these problems is that degeneration of some mechanical device beyond permissible operational design limitations has manifested itself by the generation of abnormal levels of vibration. What is vibration and what do we mean by levels of vibration? The dictionary defines vibration as “a periodic motion of the particles of an elastic body or medium in alternately opposite directions from the position of equilibrium when that equilibrium has been disturbed or the state of being vibrated or in vibratory motion as in (1) oscillation or (2) a quivering or trembling motion.”

The key elements to take away from this definition are vibration is motion, and this motion is cyclic around a position of equilibrium. How many times have you touched a machine to see if it was running? You are able to tell by touch if the motor is running because of vibration generated by motion of rotational machine components and the transmittal of these forces to the machine housing. Many parts of the machine are rotating and each one of these parts is generating its own distinctive pattern and level of vibration. The level and frequency of these vibrations are different and the human touch is not sensitive enough to discern these differences. This is where vibration detection instrumentation and signature analysis software can provide us the necessary sensitivity. Sensors are used to quantify the magnitude of vibration or how rough or smooth the machine is running. This is expressed as vibration amplitude. This magnitude of vibration is expressed as:

Displacement – The total distance traveled by the vibrating part from one extreme limit of travel to the other extreme limit of travel. This distance is also called the “peak-to-peak displacement.”

Velocity – A measurement of the speed at which a machine or machine component is moving as it undergoes oscillating motion.

Acceleration – The rate of change of velocity. Recognizing that vibrational forces are cyclic, both the magnitude of displacement and velocity change from a neutral or minimum value to some maximum. Acceleration is a value representing the maximum rate that velocity (speed of the displacement) is increasing.

GE Bently Nevada
GE Bently Nevada is a leading provider of vibration
analysis instruments and software.
Various transducers are available that will sense and provide an electrical output reflective of the vibrational displacement, velocity, or acceleration. The specific unit of measure to best evaluate the machine condition will be dependent on the machine speed and design. Several guidelines have been published to provide assistance in determination of the relative running condition of a machine. It should be said that guidelines are not absolute vibration limits above which the machine will fail and below which the machine will run indefinitely. It is impossible to establish absolute vibration limits. However, in setting up a predictive maintenance program, it is necessary to establish some severity criteria or limits above which action will be taken. Keep in mind that guidelines are not intended to be used for establishing vibration acceptance criteria for rebuilt or newly installed machines. They are to be used to evaluate the general or overall condition of machines that are already installed and operating in service. For those, setting up a predictive maintenance program, lacking experience or historical data, similar charts can serve as an excellent guide to get started.

As indicated earlier, many vibration signals are generated at one time. Once a magnitude of vibration exceeds some predetermined value, vibration signature analysis can be used in defining the machine location that is the source of the vibration and in need of repair or replacement. By using analysis equipment and software, the individual vibration signals are separated and displayed in a manner that defines the magnitude of vibration and frequency. With the understanding of machine design and operation, an individual schooled in vibration signature analysis can interpret this information to define the machine problem to a component level.

Vibration monitoring and analysis can be used to discover and diagnose a wide variety of problems related to rotating equipment. The following list provides some generally accepted abnormal equipment conditions/faults where this predictive maintenance technology can be of use in defining existing problems:
  • Unbalance
  • Eccentric rotors
  • Misalignment
  • Resonance problems
  • Mechanical looseness/weakness
  • Rotor rub
  • Sleeve-bearing problems
  • Rolling element bearing problems
  • Flow-induced vibration problems
  • Gear problems
  • Electrical problems
  • Belt drive problems
Analyzing equipment to determine the presence of these problems is not a simple and easily performed procedure. Properly performed and evaluated vibration signature analysis requires highly trained and skilled individuals, knowledgeable in both the technology and the equipment being tested. Determination of some of the problems listed is less straightforward than other problems and may require many hours of experience by the technician to properly diagnosis the condition.

To learn more about vibration analysis and critical asset monitoring, contact Flow-Tech at 410-666-3200 or visit

Article abstracted from US DOE Operations & Maintenance Best Practices Release 3.0

Thursday, October 19, 2017

Centralized Gas Monitoring for Industry

Drager REGARD 7000
The Drager REGARD 7000 is a modular and highly expandable analysis system for monitoring various gases and vapors. Suitable for gas warning systems with various levels of complexity and numbers of transmitters, the Drager REGARD 7000 also features exceptional reliability and efficiency. An additional benefit is the backward compatibility with the REGARD.

For more information in Maryland or Virginia, contact Flow-Tech at 410666-3200 or visit

Check out the video below to learn more about the Drager REGARD 7000. Thanks for watching.

Monday, October 9, 2017

5 Myths of Dust Explosion Propagation

Fike explosion testing
Dust explosion propagation testing at Fike labs.
Abstracted from
"Dust Explosion Propagation: Myths and Realities"
by Fike Corporation

The unfortunate propensity of dust explosions to destroy entire facilities and claim lives has been reported in numerous past incidents.

Powder handling processes are often comprised of interconnected enclosures and equipment. Flame and pressure resulting from a dust explosion can therefore propagate through piping, across galleries, and reach other pieces of equipment or enclosures, leading to extensive damage.

While the ability of dust explosions to propagate has been widely recognized, some misconceptions lead to the false sense of security that explosion isolation is not required.

This post will enumerate, illustrate and unravel 5 common myths about explosion propagation. Download the full Fike White Paper here, or read it in full at the bottom of this post.

Myth #1: A large amount of dust is needed for an explosion to propagate.

Dust explosions do not need large amounts of fuel to propagate.

A 1 mm layer can create a dust explosion hazard in a typical room. The explosion only needed a 1/100 inch layer of dust on the ground to fully propagate.

Myth #2: A dust explosion starting in a vented vessel cannot propagate through connected pipes.

It is a common belief that protecting an enclosure, by means of venting or suppression, will affect explosion propagation in such a manner that no explosion isolation is needed at all. 

Although venting protects a vessel from the high pressures generated by an explosion, it does not necessarily prevent the explosion from being propagated through piping into other vessels.

Myth #3: A dust explosion cannot propagate against process flow. 

An argument also often heard is that a dust explosion cannot propagate against pneumatic process flow. 

An explosion is capable of traveling both with and against process flow, even over long distances.

Myth #4: A dust explosion weakens as it propagates.

Literature includes numerous discussions about explosion behavior in interconnected vessels. 

Experimental evidence has shown that explosions not only propagate, but become increasingly more damaging.

Myth #5: Small diameter pipes do not support dust explosion propagation.

Dust explosion propagation in small pipes has always been a controversial topic. The primary argument being that flame propagation is challenged due to heat loss to the pipe walls.

While conditions for dust explosions to propagate in relatively small diameter pipes are not yet fully established, their ability to propagate has been clearly demonstrated by several researchers.

Contact Flow-Tech with any questions regarding explosion protection testing, isolation valves, vents and systems at or call 410-666-3200.

Saturday, September 30, 2017

Campus Metering: Why Meter?

Instrumentation Energy Management
Schools, universities, medical centers and federal building
use instrumentation for energy management.

Energy and water managers have long known the value of metered data. With recent advances in energy and water metering and information systems resulting in increased functionality at lower costs, obtaining these data in a cost-effective manner is now a standard practice. Whether energy and water resource managers are trying to comply with legislated and mandated metering requirements, or looking to apply accepted building management best practices, such as utility bill verification or benchmarking, today’s metering technologies can provide the information needed to meet energy and water goals, save money, and improve building operations.

Metering of energy and water utilities has seen an increase in interest, application, and technology
Clamp-on flow meter
Clamp-on flow meter (Flexim)
advancement in both the private and the public sectors. One significant driver of this heightened interest is the ongoing modernization of the nation’s electric infrastructure with the move toward the smart grid and smart meters. Another significant driver, specific to the Federal sector, includes the legislative mandates for metering of Federal buildings.

The Business Case for Metering

The application of meters to individual buildings and energy-intensive equipment provides facility managers and operators with real-time information on how much energy has been or is being used. This type of information can be used to assist in optimizing building and equipment operations, in utility procurements, and in building energy budget planning and tracking.

It is important to keep in mind that meters are not an energy efficiency/energy conservation technology per se; instead, meters and their supporting systems are resources that provide building owners and operators with data that can be used to: 
Flow computer
Flow computer (KEP)
  • Reduce energy and water use
  • Reduce energy and water costs
  • Improve overall building operations 
  • Improve equipment operations
How the metered data are used is critical to a successful metering program.

Depending on the type of data collected, these data can enable the following practices and functions:
  • Verification of utility bills
  • Comparison of utility rates
  • Proper allocation of costs or billing of reimbursable tenants 
  • Demand response or load shedding when purchasing electricity under time-based rates 
  • Measurement and verification of energy project performance 
  • Benchmarking building energy use 
  • Identifying operational efficiency improvement opportunities and retrofit project opportunities 
  • Usage reporting and tracking in support of establishing and monitoring utility budgets and costs, and in developing annual energy reports. 
Most of the metered data uses listed above will result in a reduction in energy and water costs. The degree of cost reduction realized will depend on the unit cost of the energy and water being saved and on the effectiveness with which the site analyzes the data and acts upon its findings and recommendations. Examples of additional metering benefits can include:
Inline flowmeter
Thermal dispersion flow meter (FCI)
  • Supporting efforts to attain ENERGY STAR and/or green building certifications 
  • Promoting tenant satisfaction by providing information that tenants find useful in managing their operations 
  • Prolonging equipment life (and reducing capital investment requirements) and improving its reliability by verifying the efficient operation of equipment 
  • Assessing the impact of utility price fluctuations prior to or as they happen, allowing sites/agencies to address budget shortfalls on a proactive basis. 
Metering options will change in response to new material, electronic, and sensor development, as well as new and additional requirements for real-time data information. Future expansion of a metering system should be considered, as well as introduction of new metering and sensor technologies, based on the best available information, but be careful not to over design a system, thus unnecessarily increasing its cost.

Contact Flow-Tech with questions about improving your facilities energy management systems.  

Tuesday, September 12, 2017

ADMAG TI Series AXW Magnetic Flowmeter Maintenance Manual

ADMAG TI Series AXW Magnetic Flowmeter
ADMAG AXW Magnetic Flowmeter
The ADMAG AXW™ series of magnetic flow meters has been developed based on Yokogawa's decades-long experience in Magnetic Flowmeters. The AXW series continues the tradition of high quality and reliability that has become synonymous with the Yokogawa name.

The AXW series is ideal for industrial process lines, and water supply / sewage applications. With outstanding reliability and ease of operation, developed on decades of field-proven experience, the AXW will increase user benefits while reducing total cost of ownership.

Sizes are available from 500 to 1800 mm (20 to 72 inch.) with a wide liner selection such as PTFE, Natural hard rubber, Natural soft rubber, and Polyurethane rubber lining. Offering industry standard process connections such as ASME, AWWA, EN, JIS, and AS flange standards. A submersible version is also available.

This manual provides the basic guidelines for maintenance procedures of ADMAG TI (Total Insight) Series AXW magnetic  flowmeters.

In Virginia, contact Flow-Tech for any Yokogawa instrument requirement you may have. Call 804-752-3450 or visit