As we celebrate National Columnist's Day, learn more about our monthly authors.

April 18 marks National Columnist's Day in the United States, and we would like to take this opportunity to thank our expert panel. Jim Elsey, Ray Hardee and Lev Nelik provide readers with educational, compelling content every month, and their columns are favorites among our readers. Below are the most-read online articles written by Elsey, Hardee and Nelik. 

Jim Elsey

Jim Elsey is a mechanical engineer who has focused on rotating equipment design and applications for the military and several large original equipment manufacturers for 43 years in most industrial markets around the world. Elsey is an active member of the American Society orf Mechanical Engineers, the National Association of Corrosion Engineers and the American Society for Metals. He is the general manager for Summit Pump Inc. and the principal of MaDDog Pump Consultants LLC. Elsey may be reached at

Most-read article on

10 Common Self-Priming Pump Issues

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For more of Elsey's columns, click here.

Ray Hardee

Ray Hardee is a principal founder of Engineered Software, creators of PIPE-FLO and PUMP-FLO software. At Engineered Software, he helped develop two training courses and teaches these courses internationally. He may be reached at

Most-read article on

Calculating Head Loss in a Pipeline

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For more of Hardee's columns, click here.


Lev Nelik

Lev Nelk (aka "Dr. Pump") is president of Pumping Machinery LLC, an Atlanta-based firm specializing in pump consulting, training, equipment troubleshooting and pump repairs. Dr. Nelik has 30 years of experience in pumps and pumping equipment. He may be reached at

Most-read article on

Newtonian and Non-Newtonian Fluids

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For more of Nelik's columns, click here.


To read more from our current and former columnists, visit