Dust Collection Frequently Asked Questions

/Dust Collection Frequently Asked Questions

FAQ

We have many Dust Collection Frequently Asked Questions submitted to us.  Here is a collection of the most frequently asked questions about our products and our company.

For example: Why should I buy dust collection?

Simple – 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 could easily result in worker’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 and assemblies 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 create a defective finish on the product. In addition, if dust collection is not provided for machines such as planers, the chips will lay 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 take care of these potential problems.

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 lay 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.

Refer to Designing a System. This section includes the basic information needed to design a complete central woodshop dust collection system.

If you require more information, Woodshop Dust Control book written by Sandor Nagyszalanczy has shop tested solutions to dust control so you can build the right system for your shop without complex calculations. When you are designing a larger system or need how-to information on a continual basic, the Industrial Ventilation, A Manual of Recommended Practice, written by the American Conference of Governmental Industrial Hygienists is the reference source you need. The manual contains a wealth of information on designing Dust and Fume Collection system.

When you have completed your design, our staff can look over your design and make recommendations. The following information will help YOU in designing your dust collection system: A scaled layout of your shop, designating machinery locations with outlet sizes or dust hoods. Ceiling height, you’re preferable running of the main duct, and obstructions such as columns, beams, etc. Preferred location of the dust collector and type of dust to be collected. Designated machines that will run simultaneously in the shop.

There are many woodworkers that buy a dust collector on the basis of a CFM number. Unfortunately, the air volume they are given is called “free air delivery”, which means there is not any pipe attached to the dust collector. This CFM number may very well be enough air to evacuate the machines, but when you add pipe to the collector you add resistance (static pressure). When resistance is put on a collector, the CFM delivery decreases. The actual air delivery of a dust collector is typically half of the “free air” factor once it is piped in. It is important to first find out your systems CFM and RESISTANCE (static pressure), then purchase the right collector. We have several tools to enable you to achieve this. A dust collector must be able to overcome the piping resistance and pull vacuum from the machines you need to operate simultaneously.

Your typical plastic pipe system conveying dust can’t be adequately grounded. As we know, 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. Interior and exterior grounding has to be considered.

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.

Solution – 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.

We use the small-end (male-end) and large-end (female-end) method of connecting the components. This is similar to the way plumbing fittings are connected. Fittings and small-end couplings are male-end to slip into pipe and flexhose. A large-end coupling (COU2) is used to make fitting-to-fitting connections. A small-end coupling (COUP) is used to connect sections of pipe. Click here for our couplings. Secure the connection with pop-rivets and silicone caulking. Wipe the silicone around the outside of the connection. By making a chemical bond, the silicone makes the connection airtight. Later if you wish to change your system, you can cut the silicone using a razor blade. This allows easy removal of the fitting.

We offer quite a variety of flexible hoses. We encourage using clear flex hose for CNC router and moulder applications. This flexible hose is called Urethane U30, (Part #U30-C). We also offer it in black, (Part #U30-B). The hose consists of a 30-mil urethane that is wire-reinforced. This urethane material has a high tear strength, and abrasion resistance to handle the chip collection required for such woodworking machines. The flex hose handles particleboard applications very effectively. It is also flexible enough to handle the stress of traversing back and forth on the moving equipment. For even more stressful, abrasive conditions, we have a 45-mil urethane flex hose, (Part #U45). It is not quite as flexible as the 30-mil material, but is considerably more durable. Applications for sawdust trailer loading, and leaf collection/street sweeping are its common practice.

Air Handling Systems has a very complete and capable fabrication facility. On a daily basis we manufacture manifolds for Weinig and Wadkin moulders as well as many others. Quite a few of the larger sanders being manufactured today require a similar type of manifold. Due to the fact that the manifolds vary according to how the main pipe is approaching the machine, we require a detailed sketch of the tap placements and specific diameters. Refer here for required sketch sample. A firm quotation will then be provided. Our turn around time on these items is 1 week to 10 days. Keep in mind that we are very diverse in the fabrication of custom round pipe and fittings in general, so don’t hesitate to forward your drawing.

Yes, Faster, Stronger, and more Cost Effectively! Many people who visit our booth at trade shows remark about the variety of sheet metal fittings. Now that they know Air Handling Systems can fabricate such variety of dust collection components, they said they would use us in place of their local sheet metal shop and obtain the parts faster and for less cost. When you need custom dust collection components, just make a sketch of your requirements with sizes of each opening, the length and width, and if required mark openings “small end” for pipe or hose and “large end” for a fitting. Air Handling Systems is your local sheet metal shop. We are just a fax away. Fax your request to (800) 438-7135 for fast fabrication and delivery at a sensible cost.

Air Handling Systems is located in Woodbridge, Connecticut. Our facility is convenient to both I-95 and the Merritt Parkway. We are approximately 90 minutes east of New York City. We can UPS many orders. For these orders we fabricate spiral pipe in 5’ sections. Spiral pipe in 5-foot sections can be easily shipped by UPS from 3″ to 16″ diameters. (All other spiral pipe will be shipped by common carrier.) On rush orders, we can also handle your Next Day, Second Day or 3-Day Select requests. Simply provide your UPS, RPS or Federal Express account number. Every major shipping carrier serves Woodbridge. We are knowledgeable about shipping rates and carriers to different parts of the country and world. Our Shipping Department is very experienced and works to make sure the shipment goes by the most economical carrier.

We sell directly to individuals, and companies of all sizes. We do not have a minimum order/quantity requirement. If just a few parts are required for your Air Handling System, we can service your need. Place your order by calling, submitting a fax, or by mail. We accept all major credit cards: MasterCard, Visa, Discover or American Express. We ship most orders within a 48-hour time frame.

Air Handling Systems is a manufacturer and supplier of spiral pipe, fittings, and accessories for dust and fume collection. Though we do not offer dust collectors, our sales staff can provide you with various sources. Air Handling Systems is the link between the dust collector and the woodworking machines. Quality and service are always our goals.

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.

Yes, it is a good idea to locate your collector in an enclosure on an outside wall of the shop. A couple of benefits are saving floor space, and most of the noise will be contained in the enclosure. One important recommendation is to cut a filter frame near the ceiling, on the common wall between the enclosure and the shop, and insert a furnace filter. A 20″ X 20″ filter is normally adequate. This will allow air to re-circulate back into the shop. The furnace filter is inexpensive to change and will provide for cleaner air returning to the shop.

Your thought is very valid, but I would like to make a few points relative to fan units. The type of fan which is located inside your furnace, is a forward curve, otherwise known as a squirrel cage. The tips of the blades are inclined in the direction of rotation. This is the most common type of centrifugal blower, normally used in residential heating and air conditioning systems and “light duty” exhaust systems. These blowers are only capable of pressures up to approximately 1 ½” static pressure water gauge. Static pressure is pressure, which is exerted against the walls of an air duct that is created by friction and impact of air as it moves. The average static pressure of most small dust collection systems is 8″ to 10″. In other words a furnace blower does not have enough strength to overcome the static pressure of a central dust collection system. Also, the blower is not designed to handle dust. The air moved by this type of blower is generally clean. Forward curve fans are fabricated of lightweight and low cost construction.

The type of fan generally used for dust collection systems is a radial blade centrifugal. It has straight blades, which are, to an extent, self-cleaning. This makes them suitable for various kinds of material handling systems. The wheels are of simple construction and have relatively narrow blades. Housing construction is heavy duty and normally welded. They can withstand the high speeds required to operate at higher static pressures (up to 12″ water gauge).

Proper transport velocity is required to keep the material entrained in the air stream. Heavier particles require faster velocity. If the velocity is insufficient, the material will drop out and settle. To put air speed into perspective, air in dust collection piping normally moves at a velocity of 4,000 feet per minute. Air in heating and air conditioning systems normally moves at a velocity of 1,000 feet per minute.

There are two different types of dust collection, high velocity and conventional dust collection.

High velocity vacuum moves low CFM (example 50 CFM, 75 CFM, etc.), but at a terrific velocity or air speed (normally 8,000 FPM). High velocity vacuum is done in small pipes and hoses (i.e. 1″ or 2″). It is designed to lift dirt from carpets, etc.

Conventional dust collection moves a lot of air in larger pipes and hoses (4″, 5″, 6″, etc.) at a velocity sufficient to keep material flowing to the dust collector (normally at 4,000 FPM). This type of dust collector moves large quantities of air necessary to evacuate dust hoods on machinery.

Summary: If you try to pull vacuum through a 1 ½” diameter hose on a conventional dust collector, it will be like sucking a milk shake through a cocktail straw.

If you attach 2″ hose from a high velocity vacuum to a planer hood with a 5″ outlet, you will not evacuate the hood. The two sciences do not overlap. They must be treated separately.

It is not recommended to attach a filter plenum to your dust collector. First of all you do not have enough volume (CFM). Also dust collectors are for spot, source dust collection, not for general ventilation. In addition, the filter resistance is a problem.

To collect dust from a sanding operation: Attach an Air Handling Systems Nozzle (Type 3) to the end of flex hose, with the other end of the flex attached to a branch from your dust collection system. You can position the nozzle right where you are sanding.

To filter the shop air: Purchase a Delta 50-860 Air Cleaner or similar unit that you could hang in the shop or set on a workbench. This would be an efficient and inexpensive solution to filter the shop air.

*Additional notes: Watch the CFM rating on dust collection units. Most of the time, the manufacturer is referring to free air. That is how much CFM is available without any pipe hooked up yet. Once pipe, fittings and flexhose is connect to the collector, you need to factor in the Static Pressure. The more pipe, elbows, and hose used the higher your Static Pressure. The higher the Static Pressure the lower the available CFM will be. Delta and other dust collection companies offer Performance Ratings for their dust collectors that show how much CFM is available at various Static Pressures. For information on how to figure the Static Pressure for your dust collection system refer to the design instructions in our Air Handling Systems catalog.

Turn the dust collector on and off. Then, look through the grill on the end of the motor. There is a disc with fins under the grill. That disc spins the same direction as the impeller. It must be spinning so it is throwing the material directly into the outlet. Almost like whirling and throwing a lasso.

Some blowers have clockwise rotation and some have counter-clockwise rotation.

The vacuum kit is designed to help clean up the shop floor, which typically contains heavy wood chips as well as metal scraps and nails. In a single stage collector these heavy chips and metal scraps WILL damage the fan blade. Additionally, the metal scraps can potentially cause a spark from hitting the metal fan blade, which might lead to a fire. Thus the Vacuum Hose kit REQUIRES a minimum of a 5 HP two-stage collector. The two-stage collector separates the heavy chips and metal scrap from the fine dust eliminating fan blade damage as well as the risk of fire.

Can I get 1-micron filtration?

Yes, you can achieve filtration down to 1 micron with the correct fabric and surface treatment and the correct air to cloth ratio for your particular application. For wood dust we generally recommend polyester felt with a singed finish. However various applications require different weights of felt and surface treatments. Initially the polyester felt material filters the dust while building a “dust cake” on the singed surface of the felt. This dust cake then does the actual filtering of all subsequent dust that is blown into the bag. When the dust cake gets too thick, the material starts to “blind” or plug up, but the singed surface of the fabric helps to prevent a thick dust cake from adhering permanently. The dust cake will break away, leaving behind a thin layer to continue the process.

Why does my bag need to be oversized?

The purpose of an oversized bag is to achieve the proper air to cloth ratio. Most manufacturers of single stage units include the bottom bag into their calculation for air to cloth ratio. But once the bottom bag fills up that surface area is no longer capable of filtering.

What is the difference between the OEM’s standard material and polyester felt material?

Most of the OEM bags these days are made from a woven lightweight polyester sateen which has a rating of around 30 microns and a lower air flow rate than polyester felt. The felt that comes on most OEM collectors is better than the polyester sateen, but usually has no surface treatment. AFF’s singeing treatment helps promote a dust cake buildup and release which helps the bag “clean” itself as opposed to the plain felt of the OEM bags that causes dust and woodchips to adhere.

Back in the early 80’s I represented a dust collector product line. Their parent company was a leader in cartridge filters for various applications, such as engine and vehicle exhaust. After several years of research and development, the filter cartridge dust collector was introduced for fine dust filtration. The principle was to have the dust exposed to the outer pleats of cartridge where the maximum amount of surface area was located. Air was drawn through the core of the cartridge. Compared to bag filters, the cartridge provided a substantial amount of filter area in a confined space. The units provided as much filter area as a bag house and required a substantially smaller foot print. They were primarily designed for fine, dry dust. A shaker mechanism or air pulse was used to knock off any cake build up. Used properly, the cartridge filter was a major innovation to the dust collection industry. Today, there are many types of filter material and outside wrappers that can prevent cling, cake build up, and even collect mist. I applied several units to toner dust, graphite dust, glass bead dust, and lead dust, just to name a few.

Then, a few years ago, I noticed an ad for a woodworking dust collector company promoting the cartridge filter as an after filter for a cyclone. My immediate thought was, this is a misapplication. A couple months later, I noticed more ads for single stage dust collectors promoting them as a viable replacement for the upper filter bag. To my dismay, it seemed everyone jumped on the band wagon, right or wrong. At first, they were sold without a method for cleaning. I received feedback from customers that had purchased these collectors. Most said the filters were quickly getting clogged due to cake and cling. Within a short period of time, they were sold with an internal brush for cleaning. Then, came the feedback about the brushes. It appeared the cake was forced into the core filter material and clogging the pores. The replacement cost for the cartridges averaged from $200 – $300 per piece.

Some only lasted weeks and the best case I heard of was six months. These were woodworkers that used the collectors on a daily basis. Some guys were using compressed air to blow out the inside in order to use them. In some cases, this was done every other day. Bag filter material offered today is substantially improved. There are 10 oz and 16 oz polyester felts with singe to avoid cling (1-5 micron range filtration), fabrics that control electrostatic build up, special surface treatments that improve performance, fabrics that extinguish sparks, and so on. The filter bag longevity with today’s fabrics can be at least 5 years or more. If the air to cloth ratio and fabric is correct, I am convinced that the filter bag is substantially better than the reverse use of a filter cartridge. Certainly, those hundreds of dollars and hours of labor can be well spent elsewhere.

Curt Corum Sales Manager Air Handling Systems