In reply to your April 2017 newsletter and more specifically the article on energy reduction & desiccant dryers: I have experienced the dust problem related to dryers you came across in the UK, however the manifestation was not straight forward.
A bit of background:
I have had the fortune of working in a cold store that was designed by an engineer with plenty of foresight (read loads of spare capacity and other clever design tricks that made future expansion easier but that was hidden from the average eye). Our +4⁰C receiving and dispatch was linked to the -20⁰C freezer via one large reach truck door and two smaller counterbalance doors, the former door one of the 5m variety you spoke of. The three doors were served by a rather large desiccant dryer which kept the half eaten strip curtains ice free, so that the air is markedly dry, something one only notices if you spend some time in the room.
I was attending a food safety – or it could have been a health and safety meeting where the issue of a black dust epidemic in the warehouse came up, the ops manager at the time being a proactive individual had already identified a culprit, the floor. Plans for epoxy coating the receiving and dispatch was presented and contractors had already been approached. As you know, a floor does not start sprouting dust after 15 years, the problem had to come from somewhere and it was progressively getting worse. Carton dust might have been the cause, but the extent was too severe.
During the weeks that followed while we were looking for the dust devils it dawned on me that something about the counter balances trucks had changed, I did a few laps around one but could not put my finger on it, I did a few laps around another, still nothing, we checked the rest of the fleet and noticed that the bulk had “black” wheels and only a few has the white non marking wheel. It turned out that the warehouse controller had been on a cost cutting exercise and was swapping non marking counter balance truck wheels for ones with more carbon black in them. A call to the supplier confirmed that they produce dust, carbon dust. If your floor in dispatch is slightly wet, as is the case with most receiving areas without dryers, the dust is not kicked up as much and gets trapped on the floor, weekly floor scrubbing takes care of that. However this dispatch was dry with nowhere else for the dust to go but into the air and then everywhere.
The wheels on the machines were swapped back to non-marking type (at the higher price) and the dust epidemic of 2012 gradually subsided.
Rick du Toit – Refrigeration Solutions (Pty) Ltd
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