Sometimes low pressure at high flow works better than high pressure at low flow.
The Old Timer of Royal Oak, Mich., was a regular contributor to H&P years before we ever even heard of the internet. But most of his advice is just as ueful — and interesting — today.
So rather than leave his wisdom printed on pages archived in our storage room, I pulled out issues from the late 1980s and early 1990s and have been reproducing relevant entries in this blog. Here is my eighth entry, which was originally published in the April 1988 issue:
High pressure isn’t always the answer
When hot weather arrived, one of our shops had so much difficulty meeting its compressed air demand that we had to rent a couple portable compressors and tie their output into the shop’s air system. Our investigation revealed that the main cause of the air shortage was the number or blow-off stations — for sand, water, dust, chips, or drying — that had been added since the original compressed air system was installed. It was easy to tap into the plant air network for these nuisance jobs, but now the compressor room couldn’t meet the summer demand.
How could we provide these extra air requirements without using the central system? One of our guys had a flash of inspiration. He stopped at a hardware store and picked up a couple electric leaf blowers, made a detour to a vacuum cleaner shop to purchase a selection of nozzles, then started experimenting in our shop. In many of the blow-off applications, these portable low-horsepower/high-volume blowers did a better job than the plant’s air blowers.
But some jobs — drying, for example — needed more volume. We remembered seeing some used multi-stage industrial blowers in a nearby storage warehouse. We purchased one for trial (at about 10 cents on the dollar), and connected a drive motor and rigged an inlet filter and 60-in. outlet header feeding 4-in drop lines. We put it to work on a flow-through conveyor where just-washed parts have to be blown off and dried before they are painted. The industrial blower handled this project perfectly.
Consequently, we bought up the rest of the blowers and applied them all over the plant complex. We were eventually able to eliminate all our outside mobile compressors.
So when you think of blow-offs, think low-pressure/high-volume. Remember, it’s the mass volume that does the work on these jobs—and the low-pressure devices are much safer.