Perry’s Chemical Engineers’ Handbook

greg_mehosI own all eight editions of Perry’s Chemical Engineers’ Handbook. The ninth edition will be issued this year, and Dr. John Carson and I have written the section on bulk solids flow and hopper design. The ninth edition will include our prose!

When we were asked to contribute to the edition, I perused my previous editions to see how the subject of bulk solids handling was treated. The first edition was published in 1934. In addition to a short section on bulk solids storage and transport, the first edition of Perry’s included a section on how to use a slide rule, and its periodic table only included 73 elements. My grandfather was a chemical engineer, and I sometimes wonder if he used the first edition. I’m certain he used a slide rule. Recommendations for storing bulk materials were terse and advised “mechanical or air agitators for materials that are likely to clog the outlet.”


The text on bulk solids storage and handling remained essentially untouched in the second and third editions. When the fourth edition was published in 1963, the section was considerably revised. Guidelines included the following gems:

“Bins usually increase in economy as their height and diameters increases (sic). Best proportion for good flow of solids is obtained when bins are large in cross section and comparatively shallow. Materials are less apt to pack in such bins because of lower overhead material weight.”


“No hopper is included in some bin designs; residual bin contents are removed manually. Hoppers actually create most bin problems and the ideal bin would not include a hopper.”

When the fourth edition of Perry’s was published, Andrew Jenike had not yet published Bulletin 123, so it’s not surprising that the editors were not fond of hoppers. Before Jenike developed appropriate bulk solids tests, including cohesive strength, compressibility, wall friction, and permeability, designs were based on rules of thumb or ease of calculations or fabrication.

In the fifth edition published in 1973, Perry’s Handbook included Jenike’s test and design methods. The fifth edition was the first to describe solids flow patterns, shear cell test methods, and Jenike’s “design criteria” for hoppers, bins and silos. The fifth edition praised Jenike’s work and noted that engineers could now design bulk solids handling plants with the same level of confidence they had when designing processes for liquids and gases.

The subsection on bulk solids handling remained largely the same in the sixth and seventh editions. However, methods for designing hoppers, bins, and silos do not appear in the current eighth edition. Fortunately, Karl Jacob (Dow Chemical Company), the editor of the bulk solids handling and transport section of the ninth edition of Perry’s Chemical Engineers’ Handbook, asked Jenike & Johanson to contribute. I look forward to adding the ninth edition to my collection!

One Response to Perry’s Chemical Engineers’ Handbook

  1. Congratulations to Greg Mehos and the whole Jenike & Johanson team! As a polymer chemist, I have great respect for your engineering expertise in processing and packaging of polymer granules, powders, and pellets. Without this knowledge, manufacturing would be still using hand held paddles and shovels to move product in chutes and vats.