Flow Line Options Newsletter: Issue No. 2
In this issue...
- Feature Article (first of a series): Flow Meter Basics
- New Product Announcement: Compact, Clamp On Ultrasonic Flow Meter
- TECH TIDBIT: Calculating the "Bang" of Water Hammer
- NEW: Flow Line Options CD-ROM Catalog!
- A Bit of Humor
Feature Article
Selecting a flowmeter can be a daunting task. There are dozens of meter types, hundreds of manufacturers, and everyone says their meter is "best."
In truth, there is no "best" meter given the infinite combinations of fluids, pressures, temperatures, and application requirements demanded by the market. It's not uncommon to find different meter types used in a single plant for similar applications. Flow Line Options offers a variety of excellent flow metering devices, and offers the following information to help guide your selection.
Flow Meter Basics
For selecting a flow meter, you must first consider your application requirements. Flowmeters have varying degrees of accuracy and repeatability. While a meter must be repeatable to be accurate, repeatability is not always a measure of accuracy.
However, for many applications, the repeatability is more important than accuracy. For example, there are situations such as cooling flows where the absolute flow rate is neither known nor importantthe concern is maintaining the flow at a point where the desired result is obtained.
Other concerns are readout options. These may be as simple as reading the rate of flow on an analog indicator or total on a mechanical register, or as complex as having sophisticated control options including electronic outputs, alarms, totalization, and/or dynamic compensation for changing fluid conditions.
Regardless, the following information should always be known to select the proper flow meter:
- Fluid name
- The fluid specific gravity (or density)
- Flow range to be metered (even needed for flow totalizing applications); if you do not know the flow, look for Flo-Corp's next newsletter that will include an article on "guestimating" flow
- The operating pressure and temperature of your application; if these will change, the minimum, normal, and maximum values should be communicated to the flow meter supplier
- Material preferences, particularly in the case of corrosive fluids
- Pipe size and/or connection requirements; if an open channel flow, the type of weir or flume, if present, should be identified
- If electronic accessories, such as 4-20mA outputs, remote totalizers, alarms and the like, are required, what is the available input power
- Unusual circumstances, such as environmental concerns that might include weather exposure, powerful magnetic fields, hazardous areas, excessive vibration, or spacial limitations as just a few examples
From that information, we will try to match you with the most appropriate meter in the tabulation below. To learn more about each of the meter types shown, please visit our Flow Meter Index page.
In our next issue, we'll offer some other useful tips for selecting the best meter for your requirements.
|
Meter Type |
Liquid |
Gas |
Steam |
Remarks |
|
X |
X |
X |
Versatile, general purpose flowmeters for installation on pipe sizes from 1/2 4" only. Commonly found in industrial service, water treatment, compressed air and gases, plating and pickling lines, annealing atmospheres and combustion applications where reliable, repeatable performance is vital. These meters are easy to install, with no particular straight run piping requirements, and very low maintenance. |
|
|
Magnetic Flowmeters |
X |
Extremely accurate for conductive liquids, for pipe installations from 1" up. There are no moving parts or structures to block flow, giving them good immunity to liquids with particulate matter in the stream. Normally require a minimum of 10 diameters upstream, 6 diameters downstream, straight piping. Can be mounted in many positions, but generally, require a full pipe (this is best accomplished on vertical pipe runs). |
||
|
X |
Truly non-intrusive, easy installation (sensors mounted to outside of pipe wall), and offered in portable models. Offered in both transit time and doppler technologies, these meters can handle anything from ultrapure liquids to slurries. Installation is extremely easy, as sensors are mounted to the outside of pipe (making it possible to install without interrupting flow). For best results, these meters still typically require a minimum of 10 diameters upstream, 6 diameters downstream, straight piping. Can be mounted in many positions, but generally, require a full pipe (again, best accomplished on vertical pipe runs). |
|||
|
X |
Best applied on clean, lubricating fluids; one of the best values in terms of accuracy to price performance. Turbine meters require minimum of 10 diameters upstream, 6 diameters downstream, straight piping. Filtration is also important if there are any particles in the fluid, as they can damage the bearings or turbine blades of the meter. Turbine meters are typically very compact. In most applications, they should be recalibrated annually. |
|||
|
X |
X |
X |
Highly accurate meters for a variety of fluids in pipelines from 1/2 through 72 inch size. No moving parts, low pressure drop, and high rangeability or turndown. Offered in wafer, insertion and inline styles. Normally require a minimum of 10 diameters upstream, 6 diameters downstream, straight piping. Can be mounted in many positions, but generally, require a full pipe (this is best accomplished on vertical pipe runs). |
|
|
X |
Highly accurate and repeatable, typically used for registering the amount of liquid consumed over time. Normally provided with a remote signal or totalizer. Bi-directional flow may be possible in some models. |
|||
|
X |
Positive displacement units that register the total amount of liquid passed; offered in residential and industrial versions. Typically used for situation where you need to register the amount of liquid consumed over time. Normally supplied with a mechanical register, remote totalizers and alarm contacts can also be supplied. |
|||
|
X |
For open channel flows in streams, sewer pipes, and similar; two-part system consisting of a flow sensor and a weir or flume. The meter sensor is, in truth, a level gauge designed to interpret the height of the liquid stream at a weir or flume, and display it as flow. These are often found in waste water facilities, or for metering the water and sewage discharge of a plant. |
New Product Announcement: Compact, Clamp On Ultrasonic Flow Meter
The new Series TFXL is an ultrasonic flowmeter that clamps on to the outside of a pipe. It is designed to replace mechanical flowmeters in applications where liquid conditions tend to damage or impede mechanical flow meter operation. Installation of the TFXL is cost effective and requires no maintenance. The TFXL is offered on pipe sizes from 1/2” to 2” and can be ordered with or without a local display. All meters provide two flow rate outputs, 4-20mA analog and a choice of simulated turbine meter or TTL-pulse frequency, permitting the product to be interfaced with a variety of monitoring equipment. Windows ® based software utility allows users to configure, calibrate and troubleshoot.
- Series TFXL provides easy and low cost installation by clamping on the outside of existing piping systems.
- Non-invasive system allows solids to pass through the pipe with no affect on meter. Y-strainers or filtering devices are not needed.
- No maintenance is required due to no moving parts or contact with the liquid. Digital circuitry provides stable, reliable performance year after year without periodic calibration.
- Direct interface is provided to data collection systems via 4-20mA output and either TTL-pulse or simulated turbine meter outputs that are proportional to fluid flow rate.
- UltraLink Windows® software utility allows configuration, calibration and troubleshooting.
- Greater accuracy can be attained in applications consisting of entrained gases. The Series TFXL will automatically correct displayed flow rates and electronic outputs.
- Series TFXL will be used with Coal Bed Methane applications, but it will also be available for well water and any other liquids with less than 40% TSS or aeration.
- Series TFXL is a bi-directional flow measurement system. Multiple totalizers can simultaneously be operating to measure forward total, reverse total and net total.
Download Specifications (Adobe Acrobat PDF)
TECH TIDBIT: Calculating the "Bang" of Water Hammer
Water hammer is a series of pressure shocks created by a sudden change in liquid flow velocity in a pipe. The change subjects every component in the system to a pressure wave that can cause considerable damage to components within the system, and should be avoided. While there are many formulae relating to different aspects of water hammer, a simple "worst case" formula is:
Ps = Po + (64 x V x sg)
Where:
Ps = Maximum surge generated, psig
Po = Normal operating psig
V = Fluid velocity in feet per second
sg = Specific Gravity of fluid related to water
For example, if you had a glycol solution with a specific gravity of 1.07 flowing at 100 GPM in 1-1/2" Schedule 40 steel pipe (a velocity of 15.78 fps) in a system that normally operates at 50 psig, the peak pressure possible for water hammer becomes:
Ps = 50 + (64 x 15.78 x 1.07)
Ps = 1130.6 psig
NEW: Flow Line Options CD-ROM Catalog!
Have Flow Line Options on your desktop with our CD-ROM catalog.
The CD uses a browser interface and Acrobat PDF specs to make it compatible with the majority of computers. It should auto-start on most Windows computers, as well as Mac (except OS X) and UNIX. If it doesn't auto-start, a simple double-click on the Start file will launch it.
You may request your CD-ROM catalog from Flow Line Options here.
- Whenever a system becomes completely defined, someone will discover something which either abolishes the system or expands it beyond recognition.
- If builders built buildings the way programmers write programs, the first woodpecker to come along would destroy civilization.
- The opulence of the front office decor varies inversely with the solvency of the firm.
- The attention span of a computer is only as long as its cord.
- If there's a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.
- When everything seems to be working perfectly, something is wrong that you don't know about.
- The place you want to get to will always be just off the edge of the map you have handy.
- Logic is a systematic method of coming to the wrong conclusion with confidence.
- All's well that ends.
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