For  a  Clean  Safe  Shop,  Start  With
Clean Shop Air,  LLC
Designing  the  Complete  System:  What  You  Need
System Components and Product-Selection Guidelines


To determine what components you need for a complete system, start by following the air flow from each tool, completely through the system, through the final filter, and back into the shop atmosphere. Whether you have a large shop or a small one, you will need most or all of these components in your system:

Collection Hood

A shroud, hood, or other suitable structure that gathers air from around the tool and directs it to the (usually circular) port that connects to the collection ductwork.

Blast Gate

A manual or automatic gating device that opens or closes to admit air into the ductwork or seal it off. Blast gates are necessary when the dust collection system is connected to two or more tools or work areas at the same time.

Collection Ductwork

The tubing that gathers air from all hoods and blast gates and conducts it toward the central cyclone separator unit. It is important that the ductwork be completely air-tight so that no leaks can occur that would result in a reduction of air flow at the tool connected to the incoming, upstream end of the duct. To ensure adequate air flow, be sure to use 6-inch-diameter ducting all the way to the tool from the cyclone. Do not use decreasing pipe sizes as you split the ducting runs out into the shop to various tools from the single cyclone inlet.

For example, do not start with a 6-inch duct at the cyclone, then extending beyond the first wye with 5-inch, then through another wye to 4-inch, etc., as some companies suggest. The only exception would be a tool that uses two dust hoods, such as a table saw, where you would use a 6" line to the collection area underneath the saw, and a 4" line to the collection hood supported over the blade on top of the saw. Remember: You cannot use 4- or 5-inch ducting more than a few inches long and get sufficient air flow through the system to allow proper operation inside the cyclone separator.

Ductwork Fittings

Elbows carry air flow around necessary bends in the ductwork. Wyes ("Y"-shaped fittings) combine two incoming ducts into a single duct as the air is carried onward toward the cyclone separator unit. Never use "Tees" for merging incoming air ducts.

Wyes should be either straight with a side arm extending at a 45-degree angle from the main axis, or it should be symmetrical with two outlets positioned at 30-degree or 45-degree angles from the common outlet's center axis. 30-degree symmetrical wyes are preferred when available. All fittings should be well sealed around any joints and seams, especially if you use adjustable elbows. To minimize static pressure losses around bends, be sure elbows have a center-line radius that is at least one-and-one-half times the diameter of the pipe. If these are not available, use two 45-degree elbows with a straight pipe between them that is at least one pipe-diameter long.

Cyclone
Dust Separator

This is the heart of the dust collection system; a chamber where incoming air is swirled around at high speed inside the separator so that centrifugal force can drive the minute particles of micro-fine dust from the air stream toward the outer wall where it can be carried downward along the inside surface of the cone and dropped into the dust bin below for disposal. The cyclone unit must be designed and proportioned very carefully if it is to be able to maximize the amount of fine dust that is removed from the air by the cyclone itself, thus increasing the life expectancy of the final filters, and requiring less frequent cleaning of the final filters.

To ensure proper separation of extremely fine dust inside our 18-inch cyclone, you must have at least 800 CFM of actual, real-world air flow through the cyclone itself at maximum operating static pressure. Failure to accomplish this will cause excessive build-up of fine dust in the final filters.

The exceptional internal air-flow management in our cyclone designs not only produces superior fine-dust separation; it also results in remarkably low static pressure loss as air passes through the unit. This lessens the back-pressure on the blower, allowing higher air flow through the entire system for improved overall system performance and effectiveness.

Blower

The blower draws cleaned air from the top center of the cyclone separator by suction, then pushes it toward the exhaust outlet on the blower housing. To pull dust and dirt vertically upward through a duct, you must have at least 4000 feet per minute of air flow in the pipe. For 6-inch duct, that means you must have a system that delivers a solid 800 cubic feet per minute (CFM) all the time at maximum sytem static pressure.

A complete blower consists of:

  • Blower housing (available from us),
  • Impeller (we currently recommend a material-handling impeller made special for this design by Sheldons Engineering), and
  • C-face, 5-HP, 3450 RPM, compressor-duty motor (Leeson).

Just as an automobile cannot function without an engine to power it, any dust collection system requires an adequate blower to move sufficient air at a high-enough static pressure to ensure that the system works efficiently, as intended. And just as auto manufacturers tend to exaggerate horsepower ratings in order to increase the attractiveness of their products to consumers, many vendors offering dust collection systems tend to use carefully undisclosed methods to obtain CFM ratings that have little resemblance to what the unit actually produces in a real-world installation. We do not engage in such practices.

Dust Container

An air-tight dust container connected to the dust chute at the bottom of the cyclone through an air-tight connection. This can be a steel or metal drum, fiber or plastic drum, or air-tight box with air-tight door, containing a removable internal container to hold the dirt.

Typical sizes and dimensions of the dust bin vary widely from system to system, as dictated by available space, ceiling height, and other factors.

Blower Motor

The cyclone kit and blower housing are designed to use a Leeson 5-HP compressor-duty motor with C-face mounting. By special arrangements with Leeson representatives, we are now able to provide a factory-assembled C-face adaptation of that motor at competitive, very attractive pricing. The recommended motor is an excellent solution with excellent made-in-U.S.A. quality, but if you have other preferences, contact us for further information.

Exhaust Ductwork

This is the tube that carries the air from the blower as it exits from the system toward the final filter. Some systems are installed using flexible HVAC ducting for the exhaust, rather than rigid piping and elbows.

Optional Muffler

If the noise coming from the cyclone is excessive and you want it quieter, you can always add a muffler to reduce it somewhat. Some have constructed mufflers by packing an acoustically absorbant material inside a larger length of duct piping with a reducer on both ends to fit it to the exhaust ductwork. They then connect the entire assembly between the blower and the filters. One could conceivably reduce it even more by placing the final filters inside of an enclosure that is designed as an acoustical labyrinth (think of getting through a maze) with sound-absorbant walls. It becomes essentially a question of how much you want to invest in sound deadening and how much space you have available for noise reduction devices.

Also, there comes a point where vibration of the blower or motor, especially if you use an imported motor that isn't well balanced, will transfer into the cyclone separator unit, and the walls of the entire assembly can act like a loudspeaker. That is why it is necessary to have well-balanced blower impellers and motors if you want a quiet system. The impeller most commonly used in this system is reported by several buyers to be remarkably quiet, but it is a fact that when you are moving over 1000 CFM of air flow, you will get some noise. It is simply unavoidable.

Final Filter

Your Last Line
of Defense Against
Dangerous Dust

After the air is processed through whatever dust collection system you might be using, this is the point where you get safe, breathable air, or you don't. Many many manufacturers of household vacuum cleaners and consumer-grade dust collection systems, as well as some suppliers of commercial dust collection equipment do not pay proper attention and respect to this most critical element in the system, as far as your health is concerned.

This is your last line of defense in your dust-collection system. The reason for the nice, efficient, effective cyclone to separate the fine dust as well as coarse chips is so that the final filter doesn't have to do all of the work and get plugged up every few minutes when you are sanding or cutting MDF on a table saw. This is no place to be taking shortcuts to save money! If the filter plugs up, you don't get air flow, and without air flow, you don't get dust collection. If you don't have a top-performing cyclone, the only way you can lengthen the time before the filter plugs up is to open the pores on the filter and let some of the problem fine dust through, but then you end up breathing dust which leads to all of the health problems we're trying to prevent.

To ensure safe, breathable air, the filters you use must be rated at not more than 0.5 microns at 99.99% efficiency or better. Some pleated and bag-type filters are rated at 1 micron; others at 5, 10, or 30 microns. But it is the dust from .5 microns to 50 microns that can be especially dangerous, so it makes no sense to settle for coarser filters.

Electrical
Motor Controls

The 5-HP blower motor requires a very substantial contactor or controller to safely turn the blower on and off. A motor with a nameplate rating of 20 amperes cannot be used with a 20-amp contactor. Start-up currents on a 5-HP motor can run as high as 120 amps or more for a short time at start-up, and the voltages across the switch when power is interrupted can be well beyond the ratings of ordinary relays. For that reason, any contactors used must be rated for 5 horsepower at 240 volts, single-phase operation. Verify that the contactor is UL (Underwriters Laboratories) and CSA (Canadian) listed for that rating. Even though the motor may have an internal overload-protection switch, it is always better if the motor controller also includes a thermal or magnetic over-current-protection circuit that removes power from the system if a malfunction or over-current condition occurs. When buying a controller, NEMA Size 1 or IEC equivalent is recommended and preferred.

The Leeson 5-HP compressor-duty motor we carry and recommend includes a built-in overload protection device. This can be rewired by a qualified electrician so that it can also serve to disconnect the main contactor supplying power to the motor when used with a "definite-purpose contactor". This approach can be considerably less expensive than using normal integrated contactor and overload protection units that typically sell for more than the motor if it is sold at substantial discount!

So How Much Will
a Complete System
Cost Me?

Given typical prices in early 2004, a complete installation, depending on what kind of ductwork you use and how much you pay for it, will usually run about $1000, up to $1300 or $1500. If your budget is tight, we suggest starting with a good cyclone unit, and run a minimal duct to your most important tools, then upgrade later. But if you try to cut corners on the dust collection unit itself and the blower, you will find the result inadequate until it is replaced, regardless of how much you try to upgrade the ductwork. Think of it in terms of the engine in a big truck. If the engine isn't big enough, the truck can't go very fast.

Compare these costs with the typical price of a new household vacuum cleaner such as Electrolux ($950-2400), Interstate Engineering/TriStar (up to $2400), Rainbow ($1000-$1500), Kirby (same general price range, but they won't quote prices over the telephone). For the same money or less, you have clean air in your shop and clean shop air usually means you don't have sawdust all over the floor either.

Given a useful perspective, having a first-rate cyclone can be a very attractive and sensible option.


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Updated May 26, 2004

©Copyright 2004, Clarke F. Echols and Clean Shop Air, LLC. All rights reserved.
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