The Consumer Guide to Magnetic Flowmeters
The difficulty of unbiased "comparison
shopping"
One problem that faces users and
specifiers of flowmeters is how to compare the specifications
and performance of different flowmeters. This is a real problem because specifications
are often written so as to emphasize positive features,
and minimize the negative features of a particular
product.
We decided that
something could be done to assist the end users and
specifiers of flowmeters.
What was needed was a thorough, objective,
third-party assessment of the specifications of all
of the world's flowmeters.
We decided to begin
with magnetic flowmeters, because they are one of
the most commonly used technologies, both in process
and environmental applications.
We began by producing a Competitive Intelligence
Report and Marketing Intelligence Report that were
intended to be sold primarily to manufacturers and
large end-users. However,
we found that there was a real need for a simplified,
lower cost version that could be used by smaller end-users
and individual specifiers.
To this end, we
developed "The Consumer Guide to." series of books.
The first in the series was The Consumer
Guide to Magnetic Flowmeters, published by Copperhill
and Pointer and available from ISA Press. This book
is now in its second edition.
Magnetic flowmeters are not a commodity
product
How we put together our study
Recent information we developed in the course of doing
research for our series of reports "Competitive Intelligence
Survey: Magnetic Flowmeters," challenges the perception
that magnetic flowmeters are, or should be considered,
a commodity product.
Originally, we collected data on 43 companies
worldwide who sell magnetic flowmeters.
We found that 26 companies manufacture meters,
with the remainder private-labeling them from one or
more manufacturers. When the study was completed, our
list expanded to over 60 companies worldwide, including
companies in
Eastern Europe,
China,
and India.
We asked the companies to participate in our research,
and all but a few agreed to provide product specifications.
Their raw information was tabulated on over
150 data sheets that were developed specifically for
this purpose.
The types of magnetic flowmeters were further
organized into categories (see sidebar).
Within each category, each model was compared
on the basis of its published performance specifications.
If there appeared to be an omission or inconsistency
in a published specification, we sought further clarification
from the supplier.
How we analyzed the data
Tabulated and graphical performance
data revealed significant differences between models
and manufacturers of magnetic flowmeters.
Some magnetic flowmeter performance was as
much as 2-3 times poorer than that of other flowmeters
in the same category (see chart).
The calculations illustrate much
of the reason why magnetic flowmeters might be perceived
as a commodity product. Magnetic flowmeter performance specifications
are often intricate, yet suppliers often simplify
them to reflect performance only under the best operating
conditions. So
incredibly "simple" have things become that
some suppliers cannot quantify the accuracy of the
analog output signal. Yet this is important, since the analog output
is the signal most commonly used to control the process.
What the data means
End-users and consulting engineers
who know that several suppliers offer identical equipment
(except for nameplate) will be able to better control
whose equipment they purchase, and at what price. To simplify these relationships, the flowmeter
categories were tabulated by supplier along with country
of origin and/or source of manufacture.
To help select the best equipment
for an application, users would also like to know
which models perform better in a given category of
magnetic flowmeters.
To this end, within each category, each model
was ranked in order of its calculated performance.
The results of the study
The report concludes, ".while there
are differences in the electronic features associated
with different transmitters, flowmeter performance
at reference conditions was found to vary widely. Differences were especially significant at low
flow conditions that are commonly encountered in actual
flowmeter operation."
This series of reports is unique
in providing this comparison data.
We consider the results to be significant and
expect that some buying patterns and marketing strategies
may be altered as an outcome of our research.
Because of the dynamic changes in the flowmeter
marketplace due to acquisitions, product additions
and deletions, we intend to update this report as
events warrant, and make it available as a consumers'
guide utility on a continuing basis.
Books in the series
The Consumer Guide to Coriolis
Mass Flowmeters
The Consumer Guide to Differential
Pressure Flow Transmitters
The Consumer Guide to Magnetic
Flowmeters
The Consumer Guide to Ultrasonic
Flowmeters (available early 2004)
The Consumer Guide to Vortex Shedding
and Fluidic Flowmeters
All of these books are available
at the ISA Bookstore (www.isa.org).
David W. Spitzer has more than 25
years of experience in specifying, building, installing,
start-up and troubleshooting process control instrumentation.
He has developed and taught flow seminars for 20 years.
Mr. Spitzer is a member of ISA, and belongs to ASME
MFC and ISO TC30 committees. He has published a number
of books concerning the application and use of fluid
handling technology, including "The Consumer Guide
to." series that can be used to compare flowmeters
by supplier. Mr. Spitzer is currently a principal
in Spitzer and Boyes, LLC, offering engineering, product
development, marketing, and distribution consulting
for manufacturing and automation companies.
SIDEBAR - MAGNETIC FLOWMETER
CATEGORIES
- Ceramic-lined
Ceramic magnetic flowmeters
have abrasion-resistant liners typically made
of alumina ceramic instead of the typical elastomer
linings usually found in magnetic flowmeters. They often permit higher temperature operation,
and because their electrodes are typically part
of the ceramic substrate, they tend not to offer
a leak path between the electrode and liner.
