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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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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