David W. Spitzer

Sometimes you have to go down to go up. Some time ago, I was asked to audit the operation of a “sick” flowmeter installed in a horizontal pipe to measure water with some solids and recommend a replacement technology. The process was continuous, so it was not possible to examine the inside of the pipe to determine if there was any deposition of the solids. In this application, deposited solids would affect the velocity profile so the flow measurement could be adversely affected. The fluid velocity was relatively low, so I presumed there was (at least) a good chance that solids were deposited in the flowmeter.

As for the replacement flowmeter – the flowmeter was caught between constraints that would not budge. First, the flowmeter should be located in a vertical pipe so that solid deposition would not be an issue. That said, the piping had to be located within the boundaries of the pump house floor and the pump house ceiling. Careful sizing revealed there was (barely) sufficient space to locate the required straight run for the new flowmeter – if the flowmeter run started at the floor and went to the ceiling.

However, the discharge of the pump check valve and the pump house discharge pipe were at the same elevations about half way between the floor and the ceiling. In order to install the flowmeter in the vertical pipe, the pump check valve discharge piping would have to be routed down to the floor, then up to the ceiling, and then down to the pump house discharge pipe. Needless to say, this installation was considerably more expensive than locating the flowmeter in a horizontal run between the pump check valve and the pump house discharge.

As such, there was extreme (political) pressure to locate the flowmeter in a horizontal run. Standing your ground to get things right is not always easy. Sometimes you have to go down to go up – and then go down again.

David W. Spitzer
is a regular contributor to Flow Control with more than 35 years of experience in specifying, building, installing, startup, troubleshooting and teaching process control instrumentation. Mr. Spitzer has written over 10 books and 150 technical articles about instrumentation and process control, including the popular “Consumer Guide” series that compares flowmeters by supplier. Mr. Spitzer is a principal in Spitzer and Boyes LLC, offering engineering, expert witness, development, marketing, and distribution consulting for manufacturing and automation companies. He can be reached at 845 623-1830.