Explanation of OSHA Standard 1910.242(b)

Open air lines and homemade blow offs violate OSHA standard 1910.242(b) because of harmful dead end pressures. In 1972, OSHA established Standard 29 CFR 1910.242(b) requiring that the outlet pressure of an open pipe, nozzle, air gun, etc., when used for cleaning purposes, must remain below 30 PSI with the intent to protect workers from serious injury. They determined that when dead-ended against the skin, if the outlet pressure reached 30 PSI 0r higher,  it posed a risk of entering the bloodstream through the skin. This is commonly referred to as an air embolism – a serious condition which can be life threatening. Once air has entered the bloodstream, it can restrict the free movement of blood throughout the body, disrupting normal heart function, leading to abnormal heart rhythm, possible lung or brain damage, cardiac arrest, stroke or possible death.

OSHA explains that you can use compressed air for cleaning purposes, as long as the outlet or source is fitted with some type of relief device that drops the outlet pressure to below 30 PSI if dead ended. There are basically two ways to go about gaining compliance. The first is to regulate the operating supply pressure to less than 30 PSI, assuring that the outlet pressure doesn’t exceed the threshold. While this does comply with the Standard, it can negatively affect the performance by reducing the strength of the outlet flow, limiting the usefulness of the blowoff device.

The other method is to use some type of nozzle which includes a pressure reducer or a relief device which will reduce the air pressure to less than 30 PSI if the nozzle is dead ended.

For example, EXAIR engineered air nozzles are designed so the outlet holes cannot be blocked directly. Any potential obstruction of the outlet air holes results in the air having an alternative exit path to avoid injury to operators and personnel.

sag-osha-compliant

With our Super Air Nozzles, the air exits through a series of jets, recessed behind an array fins so the exhausting airflow can never be blocked.

With the design of our Super Air Knife, the cap overlaps the body, leaving a gap on both sides of the knife, allowing the exhausting air to safely vent.

osha-sak

Picture of the Super Air Knife, showing how the cap overlaps the body and cannot be blocked, providing a safe exit path.

ALL of EXAIR‘s engineered products incorporate these principles, providing some type of relief, allowing for the air to safely vent well below the 30 PSI requirement, meeting and in many cases, exceeding the OSHA Standard.

To discuss how EXAIR can help you gain OSHA compliance to improve operator safety, avoid costly fines and improve overall efficiency, contact an application engineer for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Super Air Knife Shim Design Reduces Operation Costs

A customer of ours had an application where they needed to cool and dry parts on two conveyors that ran side by side.  A single 36″ Super Air Knife was chosen to provide coverage over the full width and to simplify the air plumbing and installation.  As we learned more about the application, it was discovered that there was 10″ section in the center where the the two conveyors butted up, where no parts would pass through, and hence no air was needed.

Fortunately, the EXAIR Super Air Knives can be supplied with custom shim designs to match the air flow requirements of the application.  These shims can be of various thicknesses to increase/decrease the air flow, of alternate materials such as a stainless steel shim in an aluminum air knife to increase the temperature range, or as in this case, designed to provide specific air flow patterns.

By utilizing the special shim design, it is estimated to save $865 per shift per year in compressed air costs versus the standard configuration.  That is a significant savings, and using less compressed air is high on everyone’s priority list.

Check out the video below to learn more about the EXAIR Air Knives.

akvideo

EXAIR manufactures 3 different types of air knives, in 4 different materials, up to 108″ in length.

To discuss your application and see how an EXAIR Intelligent Compressed Air Product can help your process, feel free to contact EXAIR and one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Twitter: @EXAIR_BB

 

 

 

High Temperature Capability

Last week, a customer called in to talk about their application.  After aluminum and steel machining operations, parts are run through a washer system. The drying portion utilized a Super Air Amplifier to dry the sides and a Super Air Knife to dry off the top. The wash temperature was running at 185°F.  The customer wanted to review the application and make sure the EXAIR products utilized in the process were rated to this temperature and to check on high the products could go, since the maximum possible temperature for the washer was listed as 250 °F.

air-knife-air-amplifer

Drying Section – Utilizing EXAIR Air Amplifier (near top) and Super Air Knife

The Super Air Amplifier is rated to 275°, above the maximum possible condition.  The Super Air Knife was pre-installed with a stainless steel shim, enabling a maximum temperature rating of 400 °F. Both of the components are rated for temperatures in excess of the maximum possible washer temperature condition, and the customer felt confident with the system design.

EXAIR has several options in the Air Amplifier and Super Air Knife product families to allow for operation in high temperature applications.  For the Air Amplifier, the Super Air Amplifier and Aluminum Adjustable Air Amplifier have a maximum temperature rating of 275°F.  The Stainless Steel Adjustable Air Amplifier is rated to 400°F, and for the hottest of conditions, the High Temperature Air Amplifier is rated to 700°F.

Relating to Super Air Knife, the aluminum Super Air Knife is rated to 180°F.  With a stainless steel shim installed, the maximum increases to 400°F. The PVDF Super Air Knife, used in applications where chemical resistance is needed, can withstand temperatures up to 275°F. And for the most extreme temperature environments, the Type 303 and Type 316 Stainless Steel Super Air Knives are rated up to 800°F.

To discuss your application and how an Air Amplifier and Super Air Knife or any EXAIR Intelligent Compressed Air Product can help your process, feel free to contact EXAIR and one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Non-Contact Wiping with the Super Air Knife

A glove manufacturer needed to decrease the reject rate with their natural rubber gloves. They were seeing brush marks in the rubber material which was a visual defect.  Their operation used a ceramic hand that was used to form the size of the glove.  After the rubber material was applied, it was dipped into water to set the material.  It would come out of the water tank, and a mechanism on the conveyor would rotate the hands to “shake” off the excess water.  It would then go over brushes to wipe the water from in between the fingers.  Much of the water had to be removed before it entered into the coagulation tank because it would affect the stretching ability of the glove.  With their current operation, they were seeing the scuff marks from the brushes which was a visual defect.  This cost them down time and product rejects.  So, they contacted EXAIR to see if we could help.

Brushes used to wipe the gloves

Brushes used to wipe the gloves

In looking at their process, they had two conveyors running side by side with each other. This made it a bit more difficult as we could only work on one side.  Being that the ceramic hand rotated around twice in 36” before hitting the brushes, I could focus in this area.  When it comes to wiping products without touching it, air is required.  And EXAIR knows how to use compressed air very efficiently, safely, and effectively.  For this application, I suggested our model 110236 Super Air Knife kit.  It has an overall length of 36” which could span the target area.  It comes with a filter, regulator, and shim set to clean and control the air flow.  It would be able to “wipe” the water off the hands like a non-contact squeegee.  The air flow from the Super Air Knife will hug the exterior portion of the hand; removing the water from the surface and in between the fingers.  They removed the brushes and did not have to worry about brush marks on the glove.

EXAIR Super Air Knife

EXAIR Super Air Knife

If you require a non-contact wiping in your application, use EXAIR Intelligent Compressed Products to accomplish this. You will not have to keep replacing items that wear or use items that cause damage to your product. EXAIR has the ability to use compressed air to create a strong force without scraping or scratching your material.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

More Power May Not Be The Solution

I can’t tell you how much it pains me to write this after last week’s blog. But, if we’re being honest here, every Tim “The Tool Man” Taylor (“More Power!”) does indeed need an Al Borland (“I don’t think so, Tim.”) As evidence of this, I had an opportunity to provide reasoned advice to a caller on the tech support line this week:

They had just purchased a Model 110224 24″ Aluminum Super Air Knife Kit. The flow it produced wasn’t powerful enough for their needs, so they installed extra shims from the Shim Set (which comes with the Kit) – increasing the shim gap to 0.009″ (which can produce a great deal more air flow and force)…more power, right?

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

Unfortunately, not. The Super Air Knife makes a hard hitting curtain of air when supplied properly…but it’s going to need a 1/2″ pipe (ID of ~5/8″) to carry enough compressed air flow to make that happen. Turns out, they were using 1/4″ tubing, which wasn’t even getting enough compressed air flow to the unit with just the 0.002″ shim installed. Putting in the extra shims actually made that worse. Once they ran a 3/4″ hose to the Air Knife (and took out those extra shims,) they were actually able to regulate the air supply back to about 60psig, which provided a strong enough air flow to solve the application.

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

Sometimes, though, compressed air product applications DO come down to a need for more power.  Next week, I’ll tell you about a caller who said he needed “the biggest and most powerful” Safety Air Gun we had – and unlike the last time I wrote a blog about that – he was RIGHT.

Russ Bowman
Application Engineer
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Super Air Knife Dries Plastic Fence Net

I recently worked with an extruded fence manufacturer who was looking to dry the material after a rinse process. The polyethylene fencing is 48″ wide with cells ranging from .25″ up to 2″ and the web is traveling at 5 meters per minute. After leaving the rinse bath, the web spans a 12′ area before being sent to a winder where they apply a tape before producing the finished rolls. It was in this area the company was looking to add a blow off device to remove the moisture to assure the tape would adhere to the surface.

construction-netting

Example of the fence, which is commonly used at construction sites as safety netting.

After discussing the details with the customer of the area that needed to be covered, I recommended they use our 48″ Super Air Knife for the application. The Super Air Knife produces a high velocity, laminar sheet of airflow across the entire length of the knife. Operating at 80 PSIG, using a 40:1 amplification rate (entrained air to compressed air) the unit produces a velocity of 11,800 feet per minute while maintaining a low sound level of only 69 dBA. Air consumption is 2.9 SCFM per inch of knife when operated at 80 PSIG. Since the customer was looking to treat both sides of the fencing, they would need to mount a unit above and below the web for effective blowoff.

Super Air Knife

The Super Air Knife provides a high velocity curtain of air at minimal compressed air usage.

The Super Air Knife is the most efficient and quietest air knife offered on the market today. Available in lengths from 3″ up to 108″ in single-piece construction and offered in aluminum, 303ss or 316ss construction, they are the perfect choice for small scale or wide coverage blowoff applications. With help selecting the best EXAIR Air Knife for your process or to discuss your application, give me a call, I’d be happy to help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Plastic orange construction fence-net image courtesy of Jnzl’s Photos via Creative Commons license.

 

EXAIR Super Air Knife vs. Blower-type Air Knife

Super Air Knife Blower Air Knife

Super Air Knife                           Blower Air Knife

A plastic company was developing thin layered films in their laboratory on a miniature prototype machine. It was designed for trial runs to make 24” wide material from various plastics, blends, and thicknesses.  They would place the plastic pellets into a hopper, and the material would be melted and extruded into a flat sheet.  To harden the material, it would land onto a cold drum, a large cylinder that had chilled water running through it.  To keep the sheet on the surface of the cold drum, they had a blower air knife.  In addition to the blower air knife, they had to use two ¼” copper air lines blowing on the outside section of the film.  Whenever they decided to make a change to their process, change material runs, or even for clean up; they had to move the blower air knife from the cold drum.  This was a hassle as it had a 3” hose attached to a blower.  It was very cumbersome and awkward to handle.  They heard about the EXAIR Super Air Knives, and they wanted me to do a comparison to their current system.  I was glad to compare the EXAIR 110224 Super Air Knife to their blower-type air knife system.

 

  1. They were getting “stretch” marks on the plastic film.
    • Blower-type air knife – Hot air is generated by the blower system. When the hot air hits the cool surface, it will cause an uneven hardening of the material, causing stretch marks.
    • Super Air Knife – It has a 40:1 amplification ratio. That means that 40 parts of the ambient air is entrained with 1 part of compressed air. Being that the ambient air is much cooler than the hot air from the blower system, it actually aides in cooling. There is no thermal shock to the material, and hardening is better and faster.
  2. They required an even force across the surface of the plastic film to keep against the cold drum.
    • Blower-type air knife – Their design had one 4” line feeding into the side of the blower air knife. This would cause 2 issues for an even force. As the velocity of the air hits the opposite side of the knife, the closed end, a turbulent air flow is developed. Also, there would be a slight negative pressures at the entrance caused by the velocity of the air entering. This turbulent mayhem and slight negative pressure are very inconsistent in force and velocity. The reason that they had to add the additional two ¼” copper lines to blow compressed air on the outside edges.
    • Super Air Knife – The flow that is delivered from the Super Air Knife is laminar. This means that the force and velocity is consistent across the entire length, even on the outside. With this even force, the film is held evenly and securely onto the cold drum.
  3. They needed maneuverability for change overs and clean up.
    • Blower-type air knife – To keep the needed pressure on the film, they had to have the blower air knife ¼” from the surface of the cold drum. So, before a change over or clean up procedure is started, they had to remove the knife and attachments. This was time consuming, cumbersome, and a headache to move.
    • Super Air Knife – With the compact design, the Super Air Knife has a large force in a small package. It has a footprint of 1 ¾” X 1 ½” X 24” long with only two ¼” NPT compressed air lines feeding it. The force measurement is equivalent from 3” to 12” away from the surface. Now, they could mount the Super Air Knife far enough to not disrupt their cleaning or change-over procedures. This saved them much time in changing to different materials and clean up.
  4. They wondered about the compressed air usage.
    • Blower-type air knife – This device does not require any compressed air to operate, but because it could not keep the film against the cold drum on the outer edges, they did have to use compressed air. With the two ¼” copper tubing at 80 psig, they were using a total of 79 SCFM of compressed air.
    • Super Air Knife – As a direct comparison to their air usage, the Super Air Knife would use 70 SCFM of compressed air at 80 psig across the entire width of the film. But with the unique design to entrain 40 parts of ambient air, it gives the Super Air Knife a powerful force. They were able to reduce the air pressure to 40 PSIG to keep the film on the cold roll, which also cut the air consumption to 41 SCFM. This efficient design helped them to save on compressed air without the added cost of the electricity to run the blower motor.
  5. Any other comparisons between the two products
    • Blower-type air knife – With the sound of the blower and the turbulent air flow, the unit was very loud. It had a sound level over 90 dBA, and with the operators working around this system, they required PPE for hearing.
    • Super Air Knife – These units are very quiet. At 40 PSIG, the sound level is only 61 dBA. (Just as a reference, the sound level is 72 dBA at 100 PSIG). This was very nice for the operators as they did not need to wear the ear plugs to work around their machine all day.

When it comes to using the EXAIR Super Air Knife, it has many benefits over the blower-type air knife. We can even include the initial cost in which we would be about 1/10 the cost of a blower-type air knife system.  For this customer above, they were delighted to replace that system with the Super Air Knife, and start running plastic film effectively, efficiently, and quietly on their miniature prototype machine.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

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