FAQ CATEGORY: Health & Safety

When the American Conference of Governmental Industrial Hygienists (ACGIH) recently lowered its recommended manganese exposure limit, it made waves in the welding world. While ACGIH limits don’t have the power of law, manufacturers pay attention. The ACGIH lowered its limit from 0.2 mg/m3 to 0.02 mg/m3, a tenfold decrease. The new limit is now much lower than OSHA’s current regulation—to be precise, it is now 250 times lower than OSHA’s limit of 5.0 mg/m3.

Fortunately, solutions exist to mitigate weld fumes that contain manganese. Source capture fume collectors can grab fumes before they affect workers and filter the toxic substance out of the air. Implementing solutions like this ensures workers’ health while also making sure you comply with air quality regulations.

Plasma cutting produces dust with extremely small particulates. This dust—though it is lingering in the air—might be invisible. The particulates are small due to the high degree of heat used in the cutting process.

Plasma cutting dust includes a number of contaminants that might be dangerous, and OSHA regulates workers’ exposure to many of these contaminants. If you aren’t sure what is floating in your air, consider doing an air quality audit. An audit will produce a comprehensive report that will tell you what is in your air and in what quantity. Using this information, you can develop a strategy for mitigating those contaminants. Most likely, a dust collection system will be required to capture the air coming off of a plasma cutting table. This will ensure that your workers are protected and that you are complying with air quality regulations.

After addressing any immediate concerns—such as seeking medical care for anyone who needs it, adding temporary ventilation or shutting down a process that is dangerous—you can start looking for the possible causes of your air quality problem. If you haven’t done an air quality audit recently, one is recommended. These audits are performed by licensed professionals who monitor your air, collect samples, analyze the data and produce a comprehensive report on your air quality. They will be able to tell you exactly what is in your air and in what quantities.

There are many good reasons to have an air quality report on file. The most significant one is the improved ability to protect your workers. It is also useful in meeting air quality regulations. The Occupational Safety and Health Administration (OSHA) issues exposure limits for many specific substances, and only by knowing what is in your air can you be sure you are complying with these regulations.

OSHA offers employers help in meeting these regulations. Their Compliance Assistance Specialists can identify ways a facility is falling short and can advise on ways to bring it into compliance. If a company gets an OSHA on-site consultation, it cannot result in penalties or citations.

Many options exist to remedy air quality problems. Increasing ventilation can reduce workers’ exposure to contaminants. If the volume of contaminants is high or if those substances are toxic, a more intensive solution would likely be required. A dust or fume collector that filters the air would protect workers throughout a facility and would also ensure regulatory compliance. High-volume applications like robotic welding cells would call for a source capture unit, which grabs the weld fumes at the source. Applications where the contaminants are less toxic could possibly be addressed by ambient capture equipment. These dust collectors circulate the air in a facility and filter out the contaminants, making sure everyone in the facility is protected.

Poor air quality can cause problems beyond inhalation risks. One of the greatest of these risks comes when oil mists are created in your facility. These mists can accumulate on surfaces and cause slip-and-fall hazards. Fortunately, specially designed dust collectors fitted with the right kind of filters can pull oil mists out of the air and prevent this problem.

Another major risk is that of explosions caused by combustible dust. When this dust combines with oxygen in a certain proportion, a single spark can cause it to explode. Even dusts that seem benign—such as wood dust or wheat flour—can lead to huge explosions in these conditions. Exhausting or filtering these dusts is crucial for ensuring that they don’t accumulate in the air or on surfaces in a facility. Spark arrestance and other fire protection measures in the dust collectors make sure sparks don’t develop within the equipment or ductwork.

This equipment should be a last resort. Masks may seem attractive, at first, given that they offer the impression of protection and seem cheaper than a comprehensive filtration system. However, they have many significant drawbacks, including:

• Masks often fit poorly, especially over facial hair. A poorly fitting mask might not keep out dangerous particulates.
• Units are cumbersome and uncomfortable. A common sight is workers pulling off their masks as soon as their task is complete, regardless of the air quality around them.
• Powered units need batteries that must be charged frequently.
• When personal protective equipment is the only air quality remedy being used, other workers not wearing masks in the facility will be exposed. Even small amounts of certain particulates can cause serious health problems.
• When masks are the only remedy to air quality problems, regulatory compliance will likely be in danger.
• In these facilities, the air quality will be visibly poor, creating an image problem for visitors, customers and new recruits.
• Untreated air can also damage equipment, as dust and grime accumulates on surfaces and in machinery.
• Personal protective equipment is expensive, in the long run. While the initial investment may seem modest, there are long-term costs that are unavoidable. In particular, disposable filters must be replaced frequently—a cost that adds up quickly.

Yes. RoboVent’s eQ™: Air Quality Monitoring System analyzes your air in real time. If contaminants reach a certain threshold, the system can turn air filtration equipment on. Once the air is cleaned, the system can turn the equipment off, ensuring that the equipment only runs when needed. This results in serious energy savings.

Being able to monitor your air quality in real time yields other benefits, as well. Improved air quality means boosts in employee moral and performance. Factory equipment lasts longer, since you can avoid the accumulation of dust and grime—things that can damage equipment. The filter life of your dust collectors is longer, as well.

The chemicals in your smoke depend on the process that produces them. For example, the chemicals in weld smoke are determined by the nature of the weld wire, what style of welding is being used, the gases being used, the material being welded and any possible residue on that material.

Certain materials are notorious for producing harmful chemicals when cut or welded. For example, welding stainless steel produces particulates of hexavelent chromium, a carcinogenic substance highly regulated by the Occupational Safety and Health Administration (OSHA).

Unfortunately, you can’t look at your air and know for sure which contaminants are present in it. Manufacturers should conduct an air quality audit to understand what substances are in their air. These audits are performed by licensed, third-party professionals who set up equipment to monitor air quality. After collecting samples, they analyze the data and produce a comprehensive report on the volume and nature of contaminants in your air.

Air quality engineers can help you address any air quality problems you might have. They will understand which contaminants have special regulations that demand attention. They can design and implement an air filtration solution that addresses those contaminants, as well as general air quality.

How to Remove Moisture from Compressed Air

Moisture in the air will find its way into a compressed air system, and this can cause problems because air needs to be dry for an efficient system to function properly. Finding a solution to these kinds of issues is not always easy, because compressed air has multiple application functions and compressor designs.

If we see moisture in your compressed air lines during a service visit, we will bring this to your attention so your plant can address the issue with the compressed air supplier. Having moisture present in the lines can create havoc for filter pulsing systems as it may deliver moisture into the filter cabinet. Any water or oil in the lines will be pulsed onto the filters which drastically reduces filter life, essentially ruining the filter media and efficacy.

Clean, dry, compressed air is required to ensure a dust collection system runs properly.

The device used to remove moisture in your pressurized air system may be a simple drain valve. Some systems might have far more complicated multi-stage air drying systems.

The type of air compressor that you are using will ultimately determine the best way to remove moisture. While some systems may be able to handle lower moisture content and do not require additional drying needs, many other systems are going to need air dried and moisture released in some form or another.

Drain Your Air Compressor Tank

The mixture of oil and water that collects at the bottom of your air compressor is usually released through the valve found at the bottom. You want to drain the air compressor after every use not only to keep moisture out but also to prevent rust or other damaging elements from amassing in the compressor system.

You can easily modify your drain to make it more easily accessible or automatic. Consider some basic pipe fittings and a ball valve, which can make draining your tank a simple matter of just turning the ball valve a quarter turn. Timed solenoid or automatic no-loss drains can also be valuable items put into the system (for tanks, filter housings, dryers, etc.).

Water Traps

To dry compressed air, the air needs enough time and surface area in the tank to cool such that the water vapor can condense into liquid water that needs to be trapped. Water traps are more common in applications requiring extremely dry air.

Water traps will work with filter regulators such that incoming cool air enters and circulates. Water will collect at the bottom of the trap and drain out while the air exits through a filter element.

Removing Moisture from Compressed Air through Dryers

Filters and separators cannot remove water vapor. They can only remove liquid moisture droplets from the compressed air system.

If you want to remove water vapor, then you will have to use a dryer. Because colder air holds less water, multiple systems are used to cool compressed air and allow water to drop out of the air to be collected and drained.

Refrigerated air dryers are one of the best ways to remove moisture from compressed air through a single unit drying system, but they can be very costly if sized incorrectly.

Your refrigerated air dryer will function much the same as an air conditioning unit. The dryer will be connected to the air compressor and cool the air to a specific temperature. Air is usually cooled to between 35˚F and 50˚F. As a result, the pressure dew point (PDP) should be 33˚F to 39˚F.

Air will be heated and sent through lines for end use after water drops out of the air and is separated. If an application requires a lower PDP, then a desiccant air dryer could be required as condensate freezes at 32˚F. A desiccant air dryer system can purify compressed air and provide air purification from -40°F PDP down to -100°F PDP.

Types of Desiccant Air Dryers

There are essentially four kinds of desiccant air dryers:

• QMOD Heatless Modular Desiccant Dryer — The QMOD is a modular heatless desiccant dryer engineered for optimum space and performance that delivers a -40˚F instrument quality or -100˚F process air for system demands. Its compact footprint saves floor space, so it fits anywhere. It can be installed in either a vertical or horizontal position, NPT connections allow for easy installation and service access, and floor mounting brackets provide stability.
• QHD Heatless Desiccant Dryer — QHD heatless desiccant dryers are designed to provide optimal performance and efficiency in a variety of applications, using a small portion of compressed air to purge and regenerate the off-line tower. The QHD series includes 13 models that deliver between 230 and 3,400 cubic feet per minute (CFM) of clean, dry air.
• QBP Blower Purge Desiccant Dryer — Quality desiccant delivers consistent performance even in harsh conditions, and stainless-steel butterfly valves with actuators ensure a long lifetime. The standard filter package comes with two pre filters and an after filter, while NPT connections allow for easy installation and service access. There are also forklift slots on the frame for easy handling, and wide vessels allow for low airspeeds and longer contact times.
• QHP Heated Purge Desiccant Dryer — An industrial duty heated purge desiccant air dryer capable of removing moisture from compressed air through the process of Heat Assisted Pressure Swing Adsorption, in which saturated compressed air is directed over a bed of desiccant. Moisture adheres to the surface of the desiccant as the saturated compressed air flows up through it and is removed through an exhaust muffler during the regenerating cycle. The dryers are more energy efficient than heatless dryers.

Air Drying Through Piping Systems

Moisture can also be removed from compressed air through the way you plumb your air lines. For example, you can cool air by using longer metal piping lengths in an up and down pattern that allows air to be cooled while the pipes absorb the heat. When this occurs, the water will drop to the bottom of the piping system, possibly into a water trap.

When the air moves through piping in an up and down pattern, the amount of moisture released decreases along the journey such that each leg will have less water than the one before it. When properly constructed, there will be no water left in the final leg. Such methods are one of the cheapest ways to dry compressed air but can be easier said than done, consult further with your local specialist.

Things to Think About When Purchasing a Compressed Air Dryer

You need to take a variety of factors into consideration when determining the best kind of air dryer for your compressed air needs. Know your dew point requirement, the utilities available to you, the type of compressor being used and your ambient air temperature.

You will also want to know your operating pressure, inlet air temperature, and airflow. Some air dryers can be eliminated based only on the water that needs to be removed for an air compressor, and the dew point will generally be the first thing you consider.

The ranges that indicate the best type of dryer for specific dew points are typically deliquescent air dryers for 0˚- 80˚ F, refrigerated air dryers for 0˚- 32˚ F, desiccant air dryers with a silica desiccant for 0˚ - 40˚ F, and desiccant air dryers with activated alumina desiccant for 0˚ - 100˚ F. It is also important to think about the capacity (or CFM rating) and pressure (PSIG) of an air compressor.

Your purchase price is only a partial cost consideration, as you must also keep in mind the cost of energy use as well as maintenance costs. Additionally, there is the cost of the pressure drop that will occur as your compressed air travels through another system. To compensate for the loss of pressure through piping, you will have to run the compressor at a slightly higher pressure with an air dryer (or a second compressor system) to achieve the same pressure for end use.

When you are struggling to drain a tank or properly install a dryer system, do not hesitate to contact RoboVent. We can review your system and determine the best possible solutions to help get you functioning properly.

RoboVent is ready to talk your compressed air needs with you. Call (888) 298-4214 or contact us online right now to let us help.