Streamlining flow instrumentation specification and documentation

One of the more tedious tasks in the design of a control system for process applications is specification of instruments. Design-related procurement and documentation requires determining what process conditions the instrument will need to withstand and measure.Process environmental requirements for each instrument include not only what chemicals are present but also the range of both pre...

By Tracy J. Coates P.E April 1, 1999

One of the more tedious tasks in the design of a control system for process applications is specification of instruments. Design-related procurement and documentation requires determining what process conditions the instrument will need to withstand and measure.

Process environmental requirements for each instrument include not only what chemicals are present but also the range of both pressure and temperature from normal and extreme conditions. In addition, these same parameters must be determined for the ambient environment outside of the process stream in which the instrument’s electronics operate in. Measurement requirements must also be defined at both normal and extreme conditions.

Documentation of these requirements is the basis for instrument procurement. Errors or lack of clarity in this documentation can result in instruments that do not function as required or fail prematurely, increasing the instrument’s cost of ownership. Another potential result of incomplete or incorrect information is that a more sophisticated (and usually more expensive) instrument than necessary may be specified for the application.

Many operations also need to improve documentation of their processes to meet FDA, OSHA (PSM), or EPA (RMP) requirements. Instrument specifications are vital for determining what is expected to be in a specific function. This is important to control system implementers for determining range and signal data, to maintenance personnel for repair and replacement data, and to the operations department as a reference document.

For control engineers faced with specifying flow instrumentation for any or all of these reasons, Fisher-Rosemount’s (Austin, Tex.) software called ‘Rosemount Flow Sizing Program for Vortex and Magnetic Flowmeters’ aids this documentation process. Rosemount’s documentation package can:

  • Perform the necessary engineering calculations for the selected instrument technology. It would be nice if the software selected the best technology for each application, but for now that’s left up to the control engineer;

  • Allows the user to input data in any of the common engineering units. The software provides a range of choices that are ‘mouse-click’ selectable. This section also includes help files that include conversion factors and other reference material;

  • Includes a physical properties database for many fluids, both liquids and gases, based on information published by American Institute of Chemical Engineers. This database supports the calculation of density, compressibility, viscosity, and other related fluid parameters based upon user input for vortex meters.
    Availability of this database improves specifier efficiency by not requiring parameter research or calculation for fluids contained in the database. It currently contains a collection of standard ‘organics’ and gases, including air, water, steam, and natural gas. For the most part, the items listed are pure components only and are not sorted as gas or liquid; and,

  • Automatically fills out the ‘instrument’ portion of an ISA-format specification sheet and then gives the user the ability to complete the rest of the form. Despite a format error in the magnetic flowmeter section, editing of its standard format is not allowed. Once completed, the specification forms are easily printed to provide the desired documentation.

Rosemount’s flow sizing software can be used for both vortex-shedding
and magnetic flowmeter specification and documentation.

Version 1.0.2 is available on CD-ROM. It can be loaded onto the hard drive of any PC running Microsoft Windows 95 or greater. The installation routine provided is easy but does not automatically load help files onto the PC. This must be done separately using a file copy.

For more information on the Rosemount Flow Sizing Program for Vortex and Magnetic Flowmeters, visit www.controleng.com/freeinfo .

Author Information
Contributing Editor, Tracy J. Coates P.E. is a consulting engineer at PCE Engineering, Johnson City, Tenn.