An 'old timer' is keen to see correct adoption of the SI system of units.
Roy Hemingway writes:
"... It is about time that the hydraulic industry started to apply the SI system correctly. I recently saw an article by our 'self appointed leaders in the hydraulics industry', boasting about presses they made with 500t of pressure!"
Oh boy - as Jim Pinto would say: this is so 'eminently pickable'!
Roy said that he would fancy to see something published to "let the cat amongst the pigeons". He faxed me a copy of the article - and yes, the mind boggles. I will not humiliate the publication (or the engineering company that proudly produced this article) by revealing their names. It is indeed a sad state of affairs when our 'experts' who are let loose on nuclear reactors and the like are seemingly unaware of the obvious difference between force and pressure.
People, we are talking school science here - not even first-year University!
Now this may come as a shock to some ... Did you know that grams, kilograms and metric tons are intended for expressing mass? And did you know that there is a thing called a Newton - which is the official unit of force? And did you know that pressure is actually an expression of force divided by the surface area over which that force is acting?
So just what the Dickens is 500t of pressure? A force of 4,9 megaNewtons acting on some indeterminable area? - And as this indeterminable area fluctuates, so will the force (if the pressure is fixed to the specified value). Obviously, they mean to specify a force, and not a pressure - so why on earth do they not? Go figure.
All right - that is enough poking fun. I do not for one moment believe that the engineering company in question is unable to design presses that are eminently suitable for their intended task. I believe that the meaningless gibberish in the published article is merely the result of total apathy towards spending the paltry 10 s it takes to understand the extreme simplicity of correct usage of the metric system. As Roy posed in his letter: "What could be simpler than MPa = N/mm²?"
I regularly receive press releases with non-metric units, which I duly convert to metric - and occasionally I have had to 'sanitise' some clangers quite similar to the example highlighted by Roy. We would certainly not be doing anybody any favours by allowing such drivel to perpetuate. (Now I have laid myself open for attack I will have to be especially careful not to let one of those whoppers get through uncorrected!)
Roy Hemingway's own conversion to metric has spawned a very useful book for engineers and technicians - take a look at 'Practical Engineering Design 1' - a goldmine of information.
Safety in Industry
Page 20 of the September issue of our sister publication, SA Instrumentation & Control, featured an article on the state of the safety of South African plants. Referring to the likelihood of a Bhopal-like disaster, was the chilling "... it could happen in South Africa."
The September issue was not yet back from the press when the news arrived telling of six dead and 147 injured (five seriously) at the scene of an explosion on a Sasol plant. While any accident is bad news, this begs the question of whether this is as bad as it will get... or are there worse accidents waiting to happen on other plants.
October's SA I&C will include an article discussing safety in nuclear power plants.
If there are others like Roy who have points that they wish to make or have addressed, please write to the editor. We want to address the interests of our readers and get some healthy interaction on the go. We trust you will enjoy Technews' second edition of Motion Control SA - a bit thicker, and laid out in a style in keeping with the new SA I&C look.
SAFPA looks a bit quiet this quarter - come on guys!
John Gibbs - editor
Send your letters to the editor: [email protected]
Do your instrumentation and control shopping at www.ibg.co.za
Visit the publisher's website: www.ibg.co.za
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