Well, no one said it didn't and couldn't, if that's what you're getting at. If it is, I think you're missing the point of the discussion.
It's a widely known and accepted fact that DC systems of all types have manufacturer-stated CFM specs that are always optimistic, and were measured under the best possible conditions. The reason? Simple marketing: to make the unit look as good as it can in the brochure. Some of these airflow numbers are wildly inflated, some less so. If there is a pattern, it is probably that the less powerful and less expensive the unit is, the more the numbers are fudged. Considering the marketing angle, this stands to reason.
You say your cyclone has a 2-1/2HP motor driving a 14" impeller, and can move, at least according to its manufacturer, 1450 CFM. The Harbor Freight dust collector that Carlos, myself, and many others here own has a motor advertised as 2HP but is known to be more like 1.5HP; it drives an 11" (I think) impeller. These numbers alone are enough to tell us that the HF unit is going to perform less well than your system. The wide difference in price of the two units further reinforces the conclusion. But it is the results of two actual tests -- one by Wynn Environmental, the other by WOOD Magazine -- that really tells the tale. These tests showed that the HF unit, which is rated at 1600 CFM, is actually only capable of moving ~550 CFM. So no matter how the HF unit may stack up against your cyclone or any other system in terms of actual, real-world performance, we already know that it is not moving nearly enough air to effectively capture the very fine dust particles that can cause health problems over the long term. Thus the issue becomes: if we accept this fact going in, what can be done to make the most of this particular unit, to allow it to perform as well as it possibly can within the limits of its own design?
(Sidebar: indeed, for a potential buyer the 1600 CFM rating of the HF unit is misleading, almost inexcusably so. Many of us who bought the unit did enough pre-purchase homework, here and elsewhere, to know that the 1600CFM rating was bogus; but until the Wynn and later the WOOD test came along, few of us had any inkling of just how bogus it was. I will guess that most of us probably figured something on the order of 800-1000 CFM was more like it; I know that was the case with me.)
Your system may well have the horsepower and impeller size to overcome the resistance of 16' feet of 6" flex hose ... and that's great ... and it would do even better if you replaced that hose with hard pipe ... but all this is mostly irrelevant here. The point of this thread is to try to help Carlos get the maximum performance out of his particular DC unit, the Harbor Freight 45378. With this machine, with its overrated motor, with its small impeller, with its test-proven sub-par airflow capability, the best performance comes from using hard pipe, with as little flex hose as possible in the system. The HF 45378 does not have the power to overcome the resistance of long runs of even the best-quality flexible hose. On the other hand, when plumbed with 4" hard pipe, it does an surprisingly good and very respectable job of keeping one's shop clean. Both of these have been proven time and again by the members here who own this same system.
It's a widely known and accepted fact that DC systems of all types have manufacturer-stated CFM specs that are always optimistic, and were measured under the best possible conditions. The reason? Simple marketing: to make the unit look as good as it can in the brochure. Some of these airflow numbers are wildly inflated, some less so. If there is a pattern, it is probably that the less powerful and less expensive the unit is, the more the numbers are fudged. Considering the marketing angle, this stands to reason.
You say your cyclone has a 2-1/2HP motor driving a 14" impeller, and can move, at least according to its manufacturer, 1450 CFM. The Harbor Freight dust collector that Carlos, myself, and many others here own has a motor advertised as 2HP but is known to be more like 1.5HP; it drives an 11" (I think) impeller. These numbers alone are enough to tell us that the HF unit is going to perform less well than your system. The wide difference in price of the two units further reinforces the conclusion. But it is the results of two actual tests -- one by Wynn Environmental, the other by WOOD Magazine -- that really tells the tale. These tests showed that the HF unit, which is rated at 1600 CFM, is actually only capable of moving ~550 CFM. So no matter how the HF unit may stack up against your cyclone or any other system in terms of actual, real-world performance, we already know that it is not moving nearly enough air to effectively capture the very fine dust particles that can cause health problems over the long term. Thus the issue becomes: if we accept this fact going in, what can be done to make the most of this particular unit, to allow it to perform as well as it possibly can within the limits of its own design?
(Sidebar: indeed, for a potential buyer the 1600 CFM rating of the HF unit is misleading, almost inexcusably so. Many of us who bought the unit did enough pre-purchase homework, here and elsewhere, to know that the 1600CFM rating was bogus; but until the Wynn and later the WOOD test came along, few of us had any inkling of just how bogus it was. I will guess that most of us probably figured something on the order of 800-1000 CFM was more like it; I know that was the case with me.)
Your system may well have the horsepower and impeller size to overcome the resistance of 16' feet of 6" flex hose ... and that's great ... and it would do even better if you replaced that hose with hard pipe ... but all this is mostly irrelevant here. The point of this thread is to try to help Carlos get the maximum performance out of his particular DC unit, the Harbor Freight 45378. With this machine, with its overrated motor, with its small impeller, with its test-proven sub-par airflow capability, the best performance comes from using hard pipe, with as little flex hose as possible in the system. The HF 45378 does not have the power to overcome the resistance of long runs of even the best-quality flexible hose. On the other hand, when plumbed with 4" hard pipe, it does an surprisingly good and very respectable job of keeping one's shop clean. Both of these have been proven time and again by the members here who own this same system.
LCHIEN
Loring in Katy, TX USA
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