DuroVac inDepth - Performance
Why the DuroVac outperforms competitive units using centrifugal exhausters.
The 15 Hp machine will pick up and convey approximately 85 pounds per minute of material using a 2"Ø ID 50 ft. long hose. Based on actual tests, this machine even conveys steel shot with a density of 375 pcf. at 85 lbs./minute.
The 20 Hp machine will pick up approximately 110 pounds per minute of material based on a material density of 80 pcf. Since the collection canister fills very quickly at this level of performance, various inexpensive external storage options are available. Please see DuroVac Options.
The 20 Hp DuroVac will support:
Both machines will easily support a fixed pipe network up to 400 ft. long without modification. This is important, because major competitive systems using centrifugal exhausters require $2500 control modifications to support a central vac pipe network. Makes this unit ideal for a "semi-central" - a portable machine with distributed short pipe networks to service mezzanines, explosion proof areas, etc. Even with the $2.5K mod, the centrifugal units cant service a pipe network more than 250-300 ft long because of their system's lower vacuum rating - 8" Hg. maximum vs. DuroVac's 12" Hg.
The best measure of performance is pickup power. The 15 Hp unit picks up 85 lbs./minute as above. Main competitive units pick up only 30% of this. This is because those units use a centrifugal vacuum pumps and the DuroVac uses a P.D. A Positive Displacement machine uses more energy and pulls harder the more the hose is filled with material; a P.D. vac pump attempts to maintain the same air volume and will draw higher amperage to maintain air flow as the system load increases.
For example, with 50 ft. of 2" I.D. hose connected to the 15 Hp unit, the system will develop about 5" Hg. and draw about 9A (assuming 460V operation). When the system begins to draw material, the vacuum increases and the amperage draw increases as the vacuum pump attempts to maintain the same air flow. The system vacuum will continue to increase as the material load increases right up to its maximum vacuum potential (12" Hg), at which point the motor will draw 18A. The difference between 5" Hg. (9A) and 12" Hg. (18A) is the units potential to do work.
A centrifugal vacuum pump will use less energy and use less air as material fills the hose. That's because a centrifugal attempts to maintain the same vacuum within the system. A centrifugal vacuum pump is a tremendous multi-operator system. This is because the flow varies with load. Connect one operator with a 1-1/2" vacuum hose and the vacuum pump may draw say 100scfm and use perhaps 7 Amps. Connect three hoses and the vacuum pump will draw 300 scfm and use perhaps 18-20 Amps. In both cases above, a centrifugal vacuum pump will draw approximately the same vacuum given the changing volume. That is why centrifugal vacuum pumps are said to have a "flat performance curve". It's also why they make such nice multi-operator systems: each operator thinks he has the system to himself.
However, the above example also reveals why the P.D. vacuum pump blows a centrifugal out of the water when it come to moving material. Because if increasing material (increasing system load) is thought of as removing hoses from a multi-operator system, it is clear that centrifugals really do suffer from reduced air flow and reduced Amperage draw just when they need it most.
In general, a P.D. powered system can be conservatively sized at 2.5 - 3.5 cfm/lb of material, whereas a centrifugal needs 5 - 7 cfm/lb of material, and it is not forgiving of plugging. A centrifugal unit draws its maximum energy when NO material is in the system and plugs easily without operator training.
Finally, a P.D. vacuum producer is far more mechanically efficient: the DuroVac draws 12" Hg. vs. a centrifugal's 8" Hg. at the same air flow with the same amperage draw. Internal tolerances and internal losses make this true.
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DuroVac Industrial Vacuums
15 Iris Crescent,
1- 888- 330- 3365
PHONE: 905-624-4003 FAX: 905-624-4641
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