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Fume Extraction Units - Telling a Good One from the Rest

Posted by Etienne Blouin on Dec 2, 2019 8:45:00 AM
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Fume extraction systems are not all created equally for welding. While the basic premise of a system is the same, and from the outside many look similar, like any product there are a variety of features and specifications that impact fume extraction welding performance in an industrial setting. The factors you will be looking at when sorting through all the choices will be items like:

  • Vacuum Type
  • Number of Connections
  • Portability
  • Design and Build
  • Power Requirements
  • Filtration Efficiency and Classification
  • System Features

With all of these factors in mind, let’s breakdown fume extraction systems for welding and identifying a quality unit from the rest of the pack.

Vacuum Type

Fume extraction system utilize two different types to capture smoke and remove fume from the welder zone:  low vacuum and high vacuum systems. For welding with a fume extraction gun, the kind of unit you want to use to connect to the welding gun is a high vacuum system. They differ from low vacuum or arm extraction units because they create a higher static pressure in order to have the flow go through a smaller hose. This high amount of pressure generated from the system allows it to overcome the restriction of the tool, whether it’s a welding gun, funnel, or small hood you attach to such a unit.

You want your unit strong enough to pull the air through the fume shroud of the torch through the vacuum unit, so you need to have as high a vacuum as possible in order to do efficient smoke extraction. Your unit should be producing the high static pressure you need.

For vacuum type, the blower is an important part of the performance, perhaps the most important. Different blower manufacturers offer different suction levels that either create more flow and less static pressure or more static pressure with less flow. Make sure your suction is at the static pressure level and flow that you need. This will be a decision relative to your welding parameters and can be difficult to determine just by reading the manufacturer available information. If you’re not sure, ask or research a little deeper, or ask your fume extraction specialist to guide you through the process.

The suction level you need depends on the tool you are using. Some torches with shroud designs require higher static pressure and flow design in order to be efficient, and others work well with lower pressure. Shrouds higher up the torch neck generally work better with higher static pressure while shrouds closer to the nozzle bore are better at lower static pressure. Ideally, newer designs will work optimally with up to 80 – 85 inches of static pressure and about 100 CFM of flow.

Single and Multi-Gun Fume Extraction Systems

Whether you decide on a single unit or a multi-gun unit extraction system, thereare advantages and disadvantages to either approach for fume extraction welding. The clear advantage for a single gun unit is you’re going to have one welder using one machine. Operationally, this allows for the fume extraction system to rest when not in use. Single fume gun units are smaller so they are easier to place. Single units also can be close to the feeder with the connections, meaning you don’t need a long flexible hose to reach multiple locations.

Multi-gun-fume-unitsMultiple fume gun units use a bigger, stronger housing with a larger filter that’s not as maintenance intensive. You do have to deal with longer flex hose to reach multiple welding stations. You can also see an operational cost reduction for a multiple gun machine, as using a single filter for multiple weld stations and only having to maintenance one machine as opposed to four oftentimes means less overall cost of ownership. Additionally, because many multi-gun guns fume extraction units are self-cleaning, they don’t need to be accessed as often.

On the downside, single-gun units put the responsibility for daily maintenance, filter exchange, and other such activities on the fume extraction unit on the welder. This means they are not spending as much time as possible welding. Multi-gun systems experience higher usage because of the probability that one of your welders welding at all times if you were to have 2, 3, and certainly 4 welding guns connected to a single fume extraction unit. The more fume extraction guns connected to the system, the more it will run. But as stated prior, multi-gun units are made for such use.

Portability

Portability can be very important and also practical. When using a more powerful unit they are often heavier and harder to move, even if they are billed as portable. If you look at portability alone, you would think a portable unit would be good for you, but if you wanted an extremely portable unit you also should make sure it can do the job. A fume extraction unit you can take everywhere but doesn’t properly collect weld fumes is a useless tool in the end. Portability for a fume extraction system should be practical, but power for your system has to be the most important consideration.

How-Fume-Extraction-Guns-WorkIn the world of portable fume extraction units there are all sorts of design – from heavy duty industrial designs made to resist the environment of an industrial plant setting to others made to reduce cost or reduce weight by using material that are not as resistant. Entry level units are often made from plastic pieces to be lighter and cheaper. Usually this type of build material is not ideal, as you always need to be sure the unit is going to be durable in your plant environment.

Fume Extraction System Design and Build

The design of fume extraction welding units can change from one to the other. Some are square, some are round, some have casters, some use big wheels. Your design should meet your needs for portability. If you need it to fit within a weld cart you should measure and make sure of that.

The inside design to create the static pressure and flow should all be the primary driver of the right fume extraction system for you. The power of your unit will directly determine the fume extraction capacity of the unit. A smaller unit is good with a funnel for applications that are not as power important – such as TIG welding.

If you are using a MIG gun, know that your MIG gun is a restrictive tool. Obstructions within the gun itself – things like cables, hoses, clamps, etc. all work to restrict the flow of smoke from the torch to the fume extraction system. You need to be sure your fume extraction system has enough power to overcome the restriction of the tool.

Weight is another consideration for the build of the fume extraction system. Weight is always proportional to the material used. Weight for a portable fume extraction system is driven primarily by the shell and whether it’s constructed of steel of plastic. Within the shell other system components like the blower, the filter size, and the material of the housing all have an additional impact on the weight of the unit.

Features like casters or wheels can help make even the heaviest of fume extraction system more portable and easier to move around the plant.

Don’t believe a heavier unit automatically translates to a more durable or higher performing unit, however.

Power Requirements

The power for fume extraction systems normally range from a 1-KW single-phase to a 8-KW three-phase power.

That spans a wide variety of smaller, hobbyist type fume extraction units to a large industrial high duty machine.

Portable systems normally hook up with 220 V three-phase for a high vacuum system. Lower rated fume extraction systems are able to run on 115 V single phase outlets, but beware of the performance tradeoff for static pressure with systems of lower power ratings.

Filtration Efficiency and Classification

For filtration capacity and efficiency, you have to refer to the manufacturer documentation to see the kinds of filtration capacities are available. But, it is an important factor in determining the right fume extraction system for your welding needs.

Often in North American the MERV rating is what determines the level of filtration in the unit. The highest level of filtration possible is a HEPA filter, but that’s not always required depending on the job at hand and the type of metal being welded.

Filtration capacity is defined by the size of the filter, and that is related to the filter surface and the filter material. The bigger the filter, the less flow restriction creates and the higher capacity it has. Surface, material, and size all matter and should be judged against your specific fume extraction need. Features like auto-cleaning can increase the life of smaller filters, sometimes significantly.

Classification is another consideration that helps in evaluating a quality fume extraction system. “W” classification in particular is a European rating which refers to the percentage of separation and fume class for a fume extraction system. W3 classification is a European rating that involved the level of filtration and management of the waste created by the smoke extraction process. A W3 certified fume extraction system means that the system will handle the filtration level capable of all kinds of welding processes and the manipulation around getting rid of the waste create by fume extraction.

There are classifications from W1 to W3, with W3 being practical for use in stainless steel fume extraction applications. That’s not to say non-W3 certified units can’t properly extraction weld fumes from stainless steel, but a W3-certified unit guarantees such performance. A table and explanation is provided below for reference.

Fume Class

Separation %

Application

W1

>95

Non-alloyed steel, alloyed steel with alloy components e.g. Ni and Cr, low-alloyed steel, x ≤ 5%

W2

>98

Same as W1, plus alloyed steel with alloy components e.g. Ni and Cr (5% ≤ x ≤ 30%)

W3

>99

Same as W2, plus alloyed steel with alloy components e.g. Ni and Cr (highly alloyed steel with x ≥ 30% Ni-based alloys)


System Features

There are many added features for fume extraction systems that give them an added value for manufacturers. On portable fume extraction systems, the most useful feature is a Start-Stop function. As it stops the machine when it’s not needed it thus stops the noise and stops the wear of the machine.

The only downside if it doesn’t help to cool your welding gun between welds, which happens from the system suction air into the inner tube which helps to cool consumables between welds.

Automatic clean or filter cleaning is another feature advantage that separates quality fume extraction systems from the rest. Being able to self-clean the filter and get the same performance after each cleaning. Automatic filter cleaning lets the fume extraction system clean autonomously and independent of the welder, and doesn’t need the welder to stop to initiate a cleaning.

Manual filter cleaning can achieve the same results, but depends on the welder. These systems use a wand or pump on top of the fume extraction system. The welder will have to stop welding and physically pump the wand to push the fume dust from the filter to the dust collection bin to be disposed of.

If you don’t have an automatic cleaning system, then having a sensor that tells you when the filter needs to be clean is a useful option to have. Either a noise, gauge, or light can make the manual filter changing or cleaning process more efficient and reliable. These sensors are able to know when a filter change or cleaning is needed by telling the differential pressure between the two sides of the filter, which fills it with dust and doesn’t let the air get in.

Other sensor systems notify the welder by measuring time instead of what is really happening inside the filter.

The most accurate filter cleaning sensors use differential pressure because it actually notes when there is too much dust in the filter. Basic units will mostly never come with such an alarm, so you will be reliant on your own process or maintenance schedule.

An adjustable flow function to match your process is also a very useful feature. Most of the time you can use the max power setting to weld and collect weld fumes without a problem. But if you have a situation where you don’t have as much power or you require lower than normal parameters, reducing the air flow will reduce the noise, reduce the wear, and use less power, which has a cost and efficiency advantage.

Telling a good fume extraction from the rest of the pack when having so many options in front of you can be overwhelming. Knowing your needs and welding parameters is the first step in determining the right system for you. Once you get into the process of searching and looking at different type of fume extraction systems, understanding how each feature and product specification impacts performance will go a long way in you getting the most value out of your fume extraction welding operation.

Topics: Fume Extraction