Control System Design and Operation Articles |
These are articles Jay Santos wrote (and a few that I wrote) about control system design and how to develop logic diagrams and control sequences.
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Commissioning On Campus |
This was an article I wrote for Consulting Specifying Engineer that looked at some commissioning issues that came up with the piping in a condenser water system serving a pair of cooling towers.
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Data Logging and Data Loggers |
This is a series of articles I wrote for Heating, Piping, and Air Conditioning about how to use data loggers. I still apply the same principles today when I am deploying loggers, even though the articles were written back in 2002. Stuff based on physical principles can be pretty timeless I guess.
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Steam Valve Application and Commissioning |
This is an article I wrote for Heating, Piping and Air Conditioning about steam valve application and commissioning. I also uploaded a Moore Control Application Bulletin on the topic of Course/Fine Control that illustrates an innovative way to control one-third/two-third steam valves.
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Right Sizing Equipment Articles |
These are a series of articles I wrote for Heating, Piping, and Air Conditioning Magazine about right sizing equipment.
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Analog Lessons for a Digital World |
This is an article I wrote for Networked Controls that discusses how working with pneumatic controls prepared me for working with digital controls and graphic programming languages.
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These are articles that you may find helpful in terms of providing guidance for developing control logic and control system designs.
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This was an article I wrote for Consulting Specifying Engineer that looked at some commissioning issues that came up with the piping in a condenser water system serving a pair of cooling towers.
One of the interesting things (in a nerdy sort of way) about the piping for open systems like condenser water systems is that seemingly minor differences in piping configuration can make a huge difference in how water is distributed. For instance, a non-symmetrical piping configuration in the branch lines serving the cold basins on two cooling towers that are piped in parallel that caused pressure drop difference of 0.15 psig or so in one line relative to the other could result in the basin with the higher pressure drop path overflowing while the basin with the lower pressure drop path had its make-up valve open. That is because 0.15 psig translates to 4 inches water column and the difference between the level that will cause water to run out the overflow and the level that has the make up valve open is in that range for many towers. This article looks at a number of issues of this type that came up in the field on a new construction project and is the article I referenced in my blog post titled Condenser Water Systems, Air Entrainment, and Pump Cavitation. | ||
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One of the first magazine articles I wrote ended up being the first in a series of articles on Data Logging that I did for Heating, Piping, and Air Conditioning. While the articles were written a while ago and there are several generations of data loggers between what you will see in the articles and what you will find on a the website of a vendor like Onset, the concepts in the articles still apply. So, if you are new to data logging, you may find the articles useful as a way to become familiar with data logging basics.
Since the articles are hard to find on the HPAC website, I have posted them here if you want to download them.
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This article looks at steam valve application and commissioning issues. A very common issue with steam valves is improper sizing, more specifically over-sized steam valves, which is one of the topics discussed in the article.
If you are interested in resources that discuss valve sizing, you may want to check out the MCC Powers Valve Sizing Application Engineering Bulletin or the Honeywell Gray Manual. We have learned more about the pressure drop you have target for valve sizing since these resources were written, but the basic techniques discussed in these resources can be used once you have settled on your targeted pressure drop. But even if steam valves are properly sized, they frequently need to deal with very large turn-down ratios, which can be challenging. One approach to this problem is to use two valves in parallel combined with a control strategy that sequences the valves. The course-fine_control.pdf file below is a Moore engineering application bulletin that illustrates an innovative approach for handling the valve sequencing.
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These articles look at techniques you can use to right size equipment. A lot of the techniques came from lessons I learned from my mentors during my design days, especially lessons about how to get in the ball park of the right size for a fan or a pump early on in the design phase by using some rules of thumb and basic information about the system and building to estimate static pressures, flows and heads.
I still use these lessons today as field assessment techniques in existing buildings. For instance, I may run into a pump with a nameplate head rating that seems high relative to what would actually be required given what I can see about the system. If that turns out to be true, then I have found an opportunity to optimize the pump because the extra head relative to what is needed will cause it to run out it's curve. You will find an example of that technique in the Right Sizing Pumping Systems article. Additional examples can be found in the pump_optimization_and_assessment.pdf and pumpsystemtroubleshooting_final-073108.pdf design briefs on the Energy Design Resources page of the website. A similar technique for air handling systems is alluded to in the air handling system article. You can find the details along with the details behind some of the other techniques that are mentioned in the article in the improving_mechanical_system_energy_efficiency_-_final.pdf design brief, which is also on the Energy Design Resources page of the website. | ||||
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When I first entered the industry, pneumatic controls were how it was done in the commercial building industry. Digital distributed control systems were out there in the process industry but had not made it to our industry yet. As a result, I learned control theory via a lot of hands on experience with pneumatics. There were also electric and electronic control systems that used discrete electro-mechanical components provide a control process. But pneumatic controls were by far the most common. This article is about how those early experiences paved the way for understanding DDC controls when they showed up. The theory is all the same for both strategies as are the responses of our systems to the commands of the control system. But working with pneumatics let you be hands-on with a lot of stuff that is now inside the black box called the DDC controller. If you are mechanically inclined, the hands-on experience is invaluable and I still use pneumatic controls to teach control system theory in some of the labs I do. And there still are a significant number of pneumatic control systems out there. So if you are working with existing buildings, having a working knowledge of pneumatic control is still a valuable asset. | ||
