The Light Green Machine Institute
Quick Links

Check out Nip Impressions weekly
Nip Impressions´┐Ż is Paperitalo Publications' flagship publication.  Published every Thursday afternoon (US Eastern Time), Nip Impressions´┐Ż is eagerly read by pulp and paper professionals around the world.

5 Feb 14: Materials 2 Hoods


When we presented our concept paper machine a few years ago, showing a fabric hood, people laughed.  But I (Jim Thompson) keep coming back to this.


I have seen many hood sections over the years temporarily removed and replaced with cheap tarpaulins.  The real question is why is a hood not designed this way to start with, using modern fabric materials designed for this purpose?


Hoods are dirty, hot and fire prone.  The reason these conditions exist is that access is poor.  If side walls could be rolled to the top of the hood, like rolling up a sail on a ship, there would be plenty of opportunities to clean hoods and keep their functionality in top condition.  I think we have metal hoods solely because we have always done it this way.


Any comments?  Let us know by sending an email to [email protected] with "LGMI Frontiers" in the subject line.

We received some feedback last week when we discussed computers and relief valves:

Interesting failure report on the control valves causing an expensive pressure blip


Rather than assign blame to the youngsters not having worked with mechanical equipment, I would say that they failed to visualise a failure mode, so neglected the relief valve.


I do not know the system at all, but my inclination is that any part that cannot withstand the maximum pressure in the system should have a relief valve to protect it.  That has been normal in steam systems for 100 years or more. Surely it should be same on hydraulics.


Even if the young lad's computer is perfect, there is always the possibility of valve failure or human error in adjustment.


Experience is a wonderful, but expensive, teacher.

Neil McCubben
Foster, Quebec


If you want to know the future, study the past! It's a shame that even in research, a literature search is considered to be "old fashioned" as we madly go about reinventing things that have already been discovered. Nothing is more expensive than having to learn more than once.
Best regards,
Bob Eamer


It seems to me that most design engineers assume that all systems will always work the way they are designed unless human intervention causes a problem.  The idea of some failure of the system to function as designed is simply not credible.


Those of us of another era and/or years of experience with 1:1,000,000 system malfunctions, generally assume the alternative, that all systems will eventually fail to operate as designed.  This leads to a 'what if...' set of questions and answers that, in the old days, led to the installation of fail-safe, back-up systems adequate to maybe not avoid a shutdown or some loss of productivity, but did avoid catastrophic incidences.


My experience is that in areas of insurance against loss or damage by a third party, 'what if..' exercises will have been done before the policy is written and continued insurance depends on documented long-term maintenance of these back-up or catastrophe-avoidance systems.


End users need to define 'maximum acceptable loss' (damage, production, etc.), identify system failures that could cause that loss, complete 'what if' exercises (more recently called risk analyses) on these systems and then implement appropriate protection systems.

Ed Turner
Camden, North Carolina


Well made point.


I would add that the real thing that comes with age is the tendency to spend much more time on the "What happens if?" question.


I saw that just recently where an engineer wanted to take water from one machine to use on another but hadn't considered shut days were not the same.


On components, I suggest that engineers see  potential failure of their chosen units as a weakness that the  bean-counters et al will use against their project and therefore put the thoughts to the back of their minds. Those of us who have been called out to the realities of machine breakdowns at inconvenient times and know the true costs are hopefully wiser.


In connection with the Light Green Machine Institute you might be interested in the European work on decarbonisation as indicated in the attached calling notice.


As shale gas is not likely to be available in Europe to the levels of the US and of course it is very anti-decarbonisation it could be very significant for us. At least there seems to be a recognition that industry knows its business better than government. The time scale is longer than LGMI  but the ambitions are higher.


Hope you find this interesting.


Best Regards

Chris Bennett


LGMI Design Practices
As always, your comments will be appreciated.
Think light!


Brian Brogdon, Ph.D.
Executive Director




Jim Thompson

Send us your comments by emailing Brian Brogdon
or Jim Thompson!

Available for download: 2013 LGMI Conference Presentations.
On Nip Impressions and the Light Green Machine (TM) Institute.



LGMI Weekly Ideas are presented for your consideration and inspiration only.  It is solely your responsibility to check for engineering correctness, applicability, standards, insurance policy and local, national or any other legal compliance required before implementing.  Neither The Light Green Machine (TM) Institute, Paperitalo Publications, Talo Analytic International, Inc., nor any individual associated with these entities accepts any responsibility for your application or compliance issues.

Copyright 2014 All Rights Reserved