2010 Industrial HVAC Control Case, Part I
Thomas Mason, PE
We begin with a background statement, explaining why The Design Firm received the contract to do facilities design for relocation of a successful manufacturing process for a large international firm. Next is a brief review of the original plant HVAC system, made up of 27 fans. This is followed by a review of the original 1993 electrical design for control of the fans.
As part of the 1993 controls discussion, considerable attention is given to the different type of programmable logic controller (PLC) connections available and the advantages of each, along with the Code and safety compromises of each. In this section, the presentation of the 1993 design is shown, along with comments by the field installing crew and by the current author.
The discussion of the 1993 controls design is followed by interpretation of the engineering term, “as-built”. This is examined in terms of design changes during fabrication, field fabrication changes, certified as-built drawings and, finally, photographs of the finished product. This section is enormously interesting to engineers who sit at a computer screen all day. Their innocence will be destroyed.
The story moves to 2009, when plans are made to relocate the plant to a different country, with a different climate. The process and all machines are to remain unchanged. The facilities HVAC system, must, however be redesigned. Also, HVAC performance standards and fabrication standards have changed in the intervening 15 years.
The 2009 requirement for a different 29 fans is discussed, focusing on the difference in controls requirements, and only slightly, looking at the differing performance. The first relocation HVAC controls design (RELOC-1) was a straight upgrade of what was certified to be the as-built installation. However, later examination of the photographs forced a redesign to utilize the three large control cabinets, as fabricated. This produced RELOC-2. Finally (for Part 1 of this course), the client decided to replace the three large control cabinets with three personal computers running HMI (human machine interface). This leads us to RELOC-3, which is discussed, but not performed.
Part 2 of this course will discuss the PLC and HMI design approved by the Client and the system, as fabricated by the systems integrator.
The course includes
a multiple-choice quiz at the end, which is designed to enhance the understanding
of the course materials.
Upon completion of this course, the student will be able to:
This course is intended for electrical design engineers who do not work daily with HVAC controls. It will be of value to HVAC designers who do not have direct knowledge of the electrical requirements that make their systems work. It will be of value to design and project managers who need to be able to ask the hard questions. It will be of value to engineering construction services personnel who must make last minute changes to get the systems to work.
Benefit to Attendees
The value provided by this course is in introducing concepts to persons who have not encountered them previously and to provide confidence in understanding to persons who follow previous examples but don’t understand the choices available.
In 1993, The Design Firm (TDF) received a contract to prepare construction documents for a proprietary manufacturing process at a remote location of Large International Company (LIC). The Design Firm worked well with Large International Company and when LIC decided to relocate the process, intact, to a different country, they again contracted TDF for construction documents. Because the process is proprietary and subject to trade secret laws, TDF is very careful to conceal process details when bidding the facility design. Please join a brief review of the 1993 HVAC controls design and the 2009 relocation. This part of the course stops when LIC makes a substantial scope change for HVAC controls. Part II will finish the story.
In this lesson, you are required to download and study the following course content:
Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.
This course presented representative excerpts from the 1993 HVAC controls design for a medium sized manufacturing facility. The form and content of the design material was discussed in detail, from both theoretical and practical viewpoints. An attempt was made to be professional and objective. For a more personal report on the same material, investigate the PDHonline audio version of the course.
Related Links and References
For additional technical information related to this subject, please visit the following websites or web pages:
Make-Up Air Units
(This is the plug-in sensor for a comprehensive system.)
Heavy-Duty Oil-Tight indicators, buttons and switches
PLC Common-Input, common-output, isolated-input, common-input, relay-output Cards
Relay Ladder Logic
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.