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Specifying Instrumentation Requires a Team Effort
Bob Kurczewski,
Technical Consultant

The engineering design process for specifying instrumentation is a multidiscipline engineering team effort at Matrix Technologies. The manufacturing engineering consultants (process, piping, mechanical, electrical, and instrumentation and controls) must be in constant communication with each other, throughout the entire project regarding coordination, changes, updates and deletions.

This article describes the team approach Matrix Technologies’ manufacturing engineering consultants use to specify instrumentation in industrial settings.

Shared drawings provide the foundation

Matrix Technologies’ multidiscipline engineering consultants begin with a set of drawings or documents that everything in the design will be based from, so as not to wander off course with unclear understanding of the scope of work. The process and instrumentation diagrams (P&IDs) come to mind because these are shared drawings from which process, piping, electrical, mechanical, and instrumentation and controls engineering derive their information.

Sometimes process flow diagrams, with the process design and process conditions noted, are developed by the process engineers prior to the P&IDs. The P&IDs then follow and will show more details, thus soliciting discussions on how to technically control the process correctly and efficiently. The International Society of Automation (ISA) developed an instrumentation symbols legend along with instrumentation identification letters. Many companies use this or something very similar as a standard.

Most companies have piping, process and mechanical equipment, electrical, instrumentation and controls standards. Many instrumentation standards have a preferred manufacturers list for the various types of instrumentation.

Here are some of the types of instrumentation that Matrix Technologies’ manufacturing engineering consultants specify during projects:

  • Analytical (H2S, pH, conductivity, density, humidity, combustible gas, toxic gas, oxygen concentration, turbidity, ORP)
  • Control valves and automated on/off valves, pressure regulators
  • Flow meters (coriolis, thermal mass)
  • Differential pressure flow elements (concentric, eccentric, and conditioning orifice plates, venturi tube, flow nozzles, wedge meter, pitot tube, annubar, V-cone, open channel) along with associated differential pressure flow transmitters
  • Flow switches
  • Variable are flowmeters, also known as rotameters
  • Level transmitters (radar, guided wave radar, differential pressure, ultrasonic, displacer, capacitance, floats) and level switches
  • Level gauges (magnetic, glass gauges)
  • Pressure transmitters (absolute, gauge, differential) and pressure switches
  • Thermocouple assemblies and resistance temperature detectors (RTDs) assemblies
  • Temperature transmitters and temperature switches
  • Weight load cells, summing boxes, transmitters
  • Gauges (temperature, pressure, flow)
  • Single loop controllers

Process engineering sets conditions

The multidiscipline engineering consultants need to know the process or utility service description, the process conditions, the pipe specifications, the pipe line size, the associated equipment specifications, so that we may specify the correct connection type, size, pressure rating, and materials for each of our instruments. Process engineering gives us the process conditions with their units of measurement and their desired engineering units read outs for the operation’s control systems displays. Typical control systems display:

  • Process stream (liquid, gas, steam, or water)
  • Flow – minimum, normal, maximum
  • Temperature – minimum, normal, maximum
  • Pressure – minimum, normal, maximum
  • Device downstream pressure – minimum, normal, maximum
  • Molecular weight
  • Density – minimum, normal, maximum
  • Specific gravity
  • Viscosity
  • Vapor Pressure – minimum, normal, maximum

Our manufacturing engineering consultants also need to know the installation locations (indoors, outdoors, general purpose, wash down areas, hazardous areas, etc.) for our instrumentation so that we may specify them correctly. Once we have this information we can specify each instrument. It is advantageous to use ISA’s Instrumentation Specifications Data Sheet templates, which are already developed and standardized for most types of instrumentation. We may use templates that are similar. Also, we create an instrument list and include the inputs/outputs for the electronic instruments to be connected to the control system, and any desired information for use by all involved engineering disciplines.

Process, mechanical, electrical, piping, structural and civil engineers coordinate

Coordination with the engineers that are developing the instrument loop diagrams, electrical controls schematic drawings, control panels, junction boxes, software, and commissioning/validation documents is essential. We need to coordinate with the piping engineers so that we will have enough upstream and downstream pipe diameters for our flow measuring instruments. The correct control valves’ orientations and locations are necessary as well. We give them the instruments’ and valves’ dimensional sheets. The thermowells must fit into the piping and equipment correctly, and this is reviewed as well.

The level gauges must connect to a level bridle or equipment correctly. Process, mechanical and piping engineers are involved with this. All instrumentation needs to be accessible for installation, removal and maintenance. Electrical engineers need to know any electrical service requirements for the instrumentation, such as heat tracing of impulse tubing, power for lights on level gauge glasses, and power for instruments. Structural engineers are involved to help us customize special supports for instruments. Civil engineers help in sump pits areas.

Manufacturers may be part of team, too

When putting together manufacturer’s model numbers for each instrument, catalogs have sections which show all of the options. We compare these selections to our specifications data sheet. Questions will arise and we ask our process and piping engineers about compatibilities with materials, or sizes, etc. If necessary, we contact the manufacturer or their representative to get more information as well as sizing help and verification, especially flow meters and control valves. For instrumentation mounted on tanks, equipment or vessels, we obtain their approved shop drawings to verify connections sizes, types, pressure ratings, dimensions, materials and locations. We communicate with the process engineers and piping engineers during this because their knowledge and experience is needed.

The next steps are to complete the instrument specifications data sheets with the information that we have obtained and technically check them in house, with the reviews performed by the process, piping, mechanical, electrical, and controls engineers. Once these are complete we may send these to the manufacturers’ representatives for quotations. If all is complete and correct with these instruments specifications data sheets and quotes after comparison, we submit these to our client for their review and approval.

It is our responsibility to specify the right instrumentation for the right applications, and document them for purchasing, and later for maintenance. Matrix Technologies multidiscipline engineering consultants work to make sure the clients’ manufacturing processes run smoothly and efficiently.

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about our manufacturing operations management capabilities and manufacturing process control solutions, contact Bob Kurczewski.

© Matrix Technologies, Inc.

Bob Kurczewski
Technical Consultant