David W. Spitzer, P.E.

In your adventures specifying instrumentation, you have probably encountered sales people who use a number of tactics to avoid answering questions about the specifications of their instruments. For example, the sales person might:
• have a canned answer ready that will be used regardless of the question asked
• have the “gift of gab” and naturally changes subjects
• get distracted and wander off the subject
• not know the answer to the question asked
• not be able to answer the question because the specification has not been quantified
• not be able to answer because the specification is not published
• analyze the question and find it unclear or poorly phrased

These observations may seem harsh, but they are not made to imply any lack of knowledge or malice on the part of the individuals involved. To the contrary, I find that suppliers overwhelmingly present specifications as accurately as possible and try to help users who are attempting to learn about the technology. In my particular case, suppliers actively provided specifications and answered my questions when I was investigating flowmeters and level gauges for my “Consumer Guide to …” series of books.

I understand that there are occasions when some specifications, such as humidity specifications, are not available because tests were not performed or documented. I also understand that there are some isolated specifications that are not published, but may be available when requested. I understand that there are some specifications that address proprietary information that should neither be asked for nor provided. What I do not understand, is that almost all of the suppliers of an entire type of instrument do not provide any specifications for their equipment performance.

I was confronted with this issue during the research phase of Dave Mills’ book entitled “The Consumer Guide to Industrial pH and ORP Instrumentation.” The suppliers provided Dave with extensive information regarding the performance of the pH and ORP electronic units. However, the performance associated with sensors was rarely published, even though the sensor is usually the single largest source of measurement error associated with these instruments.

As an instrument user, Dave’s request for performance specifications seems to be a reasonable request, and IEC 60746-5 (Expression of Performance of Electrochemical Analyzers, Part 5) describes these specifications for pH and ORP instruments. Yet answers to Dave’s questions about sensor performance were not forthcoming and typically ignored. To their credit, a few suppliers (Emerson Process Management, Endress+Hauser, and Honeywell) did provide information.

Discussing this issue with others who have worked with pH and ORP measurements and suppliers for years revealed that they were not aware that suppliers did not provide sensor performance specifications. This state of affairs will likely not change until users loudly demand sensor performance specifications. “The Consumer Guide to Industrial pH and ORP Instrumentation” is a step in the right direction. Now it’s your turn — ask for those sensor performance specifications.

Until information is available, buyer beware!

David W. Spitzer, P.E., is a regular contributor to Flow Control. He has more than 30 years of experience in specifying, building, installing, startup, and troubleshooting process control instrumentation. He has developed and taught seminars for over 20 years and is a member of ISA and belongs to the ASME MFC and ISO TC30 committees. Mr. Spitzer has written a number of books concerning the application and use of fluid handling technology, including the popular “Consumer Guide” series, which compares 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. He can be reached 845 623-1830.