unwritten pump rules

I make use of watch that page change a site that keeps you informed of if there are any changes on the site of your interest. It is a very good tool to use to track if anything new has been added to your site.
One of the site that i follow is www.flowcontrolnetwork.com. It belongs to Larry Bachus, founder of pump services firm Bachus Company Inc., is a regular contributor to Flow Control magazine. He is a pump consultant, lecturer, and inventor based in Nashville, Tenn.
He has currently updated his article on the rules for pumps. I have directly adopted the information from his webpage. It is an interesting read and i would recommend everyone to go through his cheats.
"At work, you might be responsible for the reliability of 50 or 300 centrifugal pumps. How can you stand next to one of these pumps, observe it, and perceive if the pump is sick or healthy? (No one teaches this at the university!) The following are a few generally accepted rules to keep in mind.
Rule No. 1: At 1,800 RPM, the impeller diameter in inches, multiplied by itself (or squared), is approximately the shutoff head of the pump in feet. Why does the first rule begin with 1,800 RPM? In the states, most industrial pumps are powered by an electric motor on 60-Hz electricity. The most popular industrial electric motor (88 percent) is a four-pole motor, meaning the rated velocity is 1,800 RPM. (The motor may have a slip factor, so the actual speed might be 1,780 or 1,750 RPM. This is indicated on the electric motor identification tag.) What is the shutoff head? The shutoff head is the beginning of the pump curve. It represents maximum elevation (in feet or meters) at zero flow. The performance curve proceeds to and ends at a point called maximum flow at zero elevation. How do you begin with inches of impeller diameter and end with approximate feet of liquid elevation? It’s too complicated to explain in this short column, but that’s the way it is. (If you would like more in-depth discussion of this issue, I encourage you to attend my next Pump Guy Seminar. See the promo box at the end of this article for details.)
The BEH of the 10-inch impeller is 88 ft., about 85 percent of the shutoff head. BEH of the nine-inch impeller is 70 ft., about 85 percent of the shutoff head. BEH of the eight-inch impeller is 54 ft., about 85 percent of the shutoff head.Why do you say, approximate? It’s just a rule or guide. It isn’t a law. It is accurate within about 5 percent. There are variables that affect the result. What if the pump/motor is not spinning at 1,800 RPM? We’ll cover this in a future “Cheat Sheet” article.
Rule No. 2: The best efficiency head (BEH) of the pump is approximately 85 percent of the shutoff head.
Rule No. 3: Operate the pump at, or close to, the BEH.The pump doesn’t want to run at shutoff head. It wants to run at the BEH or the best efficiency point (BEP) on the curve. On most pumps, the BEH is approximately 85 percent of the shutoff head. In almost all cases, the BEH is somewhere between 80 percent and 90 percent of the shutoff head. So, 85 percent is a good starting point to determine the pump’s head and flow."
For the entire article i will urge you to visit his site http://www.flowcontrolnetwork.com/issuearticle.asp?ArticleID=245
The rules dont apply to all pumps but 88% of the pumps you can work with these rules.
Njoy reading and dwelve more into the wonderful world of pumps.