Dust Control Systems - Two-Stage Dust Collectors - Ductwork - Dust Collection Hoses

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Thoughts on Dust Collection by Air Handling Systems

Why should I buy a Dust Collection system?

One important reason is to avoid the health risk. Inhaling fine wood dust can develop into respiratory illnesses as well as aggravate existing respiratory conditions. There are various types of wood dust that can also cause irritation to uncovered skin surface. Fine wood dust can stay suspended for hours. Exposing employees to this type of environment will certainly result in workman’s compensation claims or even possibly a law suit. Providing dust collection at machinery as well as self-contained ceiling suspended dust collection units will keep the shop air virtually dust free.

To produce a quality product, the workshop should be as dust free as possible. If you have ever driven in a snowstorm or rainstorm you can feel for a woodworker who has his vision impaired by clouds of sawdust. Making accurate cuts, measurements, assemblies, etc. are extremely difficult under this condition. Also, if a shop has a high concentration of wood dust in the air, the dust can be drawn into paint booths. The dust will surely create a defective finish on the product. In addition, if dust collection is not provided for machines such as planers, the chips will lie on the boards and create indentations on the planed material. Thus, again creating a defective product. Having spot dust collection on machinery and self-contained air cleaners will surely take care of these potential problems.

Two-Stage Dust Collectors

Since most woodworking dust contains coarse and fine sized particles, a two-stage dust collection system is generally recommended. A two-stage dust collector consists of a first stage cyclone, a blower and a second stage after filter.

A cyclone separator is a cone shaped vessel into which the dust-laden air enters. The dust particles’ inertia causes them to move toward the separators outer wall. As the dust particles proceed towards the outer wall the course-sized particles lose momentum. When the velocity drops on the coarse-sized particles, gravity causes them to settle into the container below. The remaining fine dust exits through a central outlet at the top and into the blower. The blower then relays the fine dust to the after filter.

It is important to know that the longer the cyclone body and cone, the better the dust separation. One major reason for using a separator is so the blower unit will only convey fine dust. In a single stage unit, coarse wood dust particles and other debris hitting the blower impeller most likely will result in blower unbalance. The condition will ruin the blower quickly. Also, a separator is used so that the after filter does not receive 100% of the dust-laden air.

Technology, Issues or Trends impacting dust collection.

Government regulations and enforcement of such regulations will continue to increase causing even greater concern for improved dust collection for woodworkers. The government regulations have always been there, however the enforcement with penalties from OSHA has greatly increased the concern of proper dust collection. The dust collector manufacturers have always provided government approved systems however with the know possibility of penalty, this has become a greater incentive to improve systems. Because of these regulations woodworkers have been challenged to understand dust collection design. With this increased understanding, systems will continue to be designed with much greater efficiency, which allows for a cleaner, safer and more productive working environment.

How does one go about grounding a plastic pipe system?

The reason people attempt to ground plastic pipe is because of the generation of static electricity. Static electricity develops when the dust particles constantly rub the plastic surface. A substantial electrical accumulation may result, which then begins to discharge into fine dust particles. It is likely an explosion will occur at some time under this condition. Both, interior and exterior grounding has to be considered. If a grounding method were available for this situation, it would be quite extensive and expensive.

Plastic pipe systems are not designed for dust collection use. A necessary diversity of fittings to meet design requirement does not exist. Also, plastic pipe elbows have a very short radius and plastic tee fittings are improper for dust removal. It is these types of problems that lead to an inefficient dust collection system.

The suggestion would be to convert over to a metal piping system. With a metal dust collection piping system you do not have the concern of static electrically developing. Elbows and other various fittings are properly designed for conveying dust. The diversity of fittings and accessories will enable you to meet design requirements. Inevitably, you will get the best performance from your dust collector.

The following is from NFPA Code Booklet #664, section A-8-2.5.5. To obtain a copy contact: National Fire Protection Agency, Quincy, MA (617) 770-3000. It states in reference to Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities:

“Nonconductive ducts, such as PVC pipe, should not be used. A ground wire or other grounding system for PVC pipe is not acceptable.”

Selecting the Proper Ductwork and Flexible hose

When selecting pipe, fittings and flex hose for woodworking dust collection there are several things that should be taken into consideration.

Pipe and fittings should be constructed of galvanized metal. If plastic material is used, static electricity will develop. On the other hand, stainless steel is extremely expensive and black iron pipe will rust quickly.
Airtight seams are necessary to avoid leakage. Sealing of field joints is critical.
Proper gauges and construction are necessary to avoid collapsing of the duct. The spiral pipe’s exterior rib provides tremendous support to withstand collapsing under vacuum. Stovepipe is designed for positive pressure and not vacuum systems (negative pressure).
All flex hose used in dust collection should have wire reinforcement. This gives the hose the required strength to withstand vacuum. There are four types of material used in flex hose recommended for dust collection: rubber, polyester neoprene, metal, and urethane.

Rubber is cost effective, durable, and utilized for most general-purpose hoses. Polyester neoprene coated hose is least likely to develop static electricity making it good for sanders. Polyester neoprene is a good general-purpose hose that are flame retardant, but not good for outdoor use! However there is an improved product called AHPLUS.

AHPLUS flex hose has outstanding durability with reinforced construction, which is designed to stand up to years of use. AHPLUS is a versatile hose created with the best qualities of our top selling hoses. It is a perfect replacement for older polyester neoprene hoses. AHPLUS comes in a distinct ROYAL BLUE, designed for increase visibility in both smaller as well as industrial settings. Qualities include improved puncture, moisture and tear resistance; higher temperature range than neoprene/fabric hoses; and tremendous versatility.

Metal flex hose is extremely durable, cost-effective but causes higher resistance against flow. Finally, urethane is one of the best materials used in manufacturing of flex hose, but it is costly. It has the best abrasion resistance, tear strength, and puncture resistance. Urethane is widely used for molders, planers, and CNC routers. What is not good for dust collection is PVC hose! PVC is used to convey fumes and is not recommended for dust collection, because of the build up of static electricity.

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