OSHA Standard 1910.242(b) – Dead-End Pressure and Chip Guarding Explained

OSHA Standard 1910.242(b) discusses the use of compressed air for cleaning and blowoff. It states that the use of compressed air for cleaning purposes is prohibited if the dead-ended pressure exceeds 30 psig. This phrase means the downstream pressure of the air nozzle or gun, used for cleaning purposes, will remain at a pressure level below 30 psig for all static conditions. In the event that dead ending occurs, the static pressure at the main orifice shall not exceed 30 psi. If it does exceed this pressure, there is a very high potential for it to create an air embolism. An air embolism, left untreated, can quickly impede the flow of blood throughout the body. This can lead to stroke, heart attack, and sometimes death. Take a look at the animation below to see how an air embolism can affect the body.

With this in mind, there are only two options for staying within compliance of this standard. Either install an engineered solution that will reduce the air pressure to less than 30 psig if dead-ended, or regulate the pressure below 30 psig. For the vast majority of operations, regulating the input pressure below 30 psig is useless. The force and flow from the nozzle at this pressure is greatly reduced and likely not enough to be effective in most applications. All of EXAIR’s Safety Air Guns are designed so that the flow cannot be dead-ended. The fins on the Super Air Nozzles are not only useful in amplifying the force by drawing in ambient air, but they also prevent an operator from completely obstructing the airflow.

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The fins of the Super Air Nozzle allow air to escape and prevent dead-end pressure from exceeding 30 psig.

In addition to being concerned about dead-end pressure, OSHA 1910.242(b) also states that compressed air used for cleaning should include effective chip guarding. By this, they mean that some method or equipment must be installed that will prevent chips and particles from coming back into the eyes or skin of the operator. In addition to offering OSHA compliant nozzles and guns, EXAIR also has Chip Shields that can be installed onto any of our Safety Air Guns. The polycarbonate shields protect the operator from any flying debris while performing a drying or blowoff operation. Simply add a “-CS” to the end of any Safety Air Gun Model number to have a Chip Shield installed on the gun.

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EXAIR’s Model 1210-PEEK-CS with Chip Shield

The Occupational Safety and Health Act of 1970 does not contain any provisions that allow for the approval or endorsement of equipment. Alteration or the misapplication of what was once a safe piece of equipment would create a dangerous scenario that is out of the control of the original manufacturer. Any nozzles or guns marketed as “OSHA approved” should immediately throw up a red flag. Identifying and implementing a safe, OSHA compliant solution rests in the hands of the manufacturer themselves. If you’ve got questions about compressed air safety or have an existing blowoff in place that does not adhere to this OSHA directive, give us a call. We’ll be sure to recommend a solution that will keep your operators and wallets safe!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

 

EXAIR Knowledge Base Makes Problem Solving Easy

EXAIR makes every effort to solve your manufacturing problems, increase your efficiency and raise the bar on your safety practices. We try to do that immediately, today, right now and we’d like you to be on your way to an improved facility by tomorrow – that is why we stock all of our cataloged products and ship same day on domestic orders received by 3 pm. In order to do that it seems you would prefer to be working with a company that’s easy to do business with, and EXAIR is easy. One way we try and achieve this is by providing as much general information as we can under the Knowledge Base section of our website.  By taking advantage of the free registration, you gain access to a variety of helpful information that can help simplify your selection process and provide the final details to complete a particular project.

Knowledge Base
The Knowledge Base can be found in the black menu bar at the top of our webpage.

Take, for example, our full CAD Library providing 3D models and 2D dimensional drawings in several different formats which can be used by MANY different programs. Whether you are looking for a .stp file for a 72″ Super Air Knife or the .dwg file for a medium sized Vortex Tube, the information is readily available for download without needing to place a call to our office.

Another useful tool is our Case Study library which features a database showcasing the  benefits of using an EXAIR product in place of existing inefficient or unsafe blowoffs. Just a few benefits to list would be compressed air savings, safety improvements, achieving OSHA compliance, an increase in production, lowering the decibel level in a work area or overall money savings. We are continually looking to add useful information to the library and can offer some EXAIR swag or an incentive in exchange for quantifiable data. (give me a call for details!)

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Example of a Case Study Report.

Maybe your looking for a specific EXAIR solution to a common industrial process? I invite you to take a look at our Application Database. From conveying plastic pellets to a hopper or needing to remove noxious fumes from a coating application, the desired information might just be a simple click away.

These are just a small sample of the useful tools available for easy use. If you can’t find the information you’re looking for or have a specific application you would like to discuss, give us a call so we can help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

A Perfect Fit for Primary Metal Manufacturing

Primary metal manufacturing and processing plants tend to have a variety of applications using compressed air, some of which can be quite large.  Our Finnish distributor found just such an application, using a high volume of compressed air under unsafe conditions.

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Homemade air gun at a metal manufacturing plant in Finland

In the photo above you can see a homemade air gun used to provide a high force blow off.  This unit has a welded cone on the end of a metal pipe using a ¼ turn ball valve to control the compressed air.  When the ball valve is turned the airflow remains constant until the operator returns the valve to the closed position.  This means that if the operator were to let go of the unit for any reason, the air gun would continue to blow, creating a safety hazard.

In addition to this concern, the welded cone at the end of the pipe provides no protection for high dead end pressures, creating a potential source of an air embolism if contacting human skin.  This can lead to difficulty breathing, chest pain, low blood pressure, or even a stroke (Source: MedScape; Venous Air Embolism; Updated December 8th, 2015).

The end user had accepted the risks associated with this homemade device because they were unaware of anything in the market capable of meeting the volume and force necessary to meet their application needs.  That is, until they were shown the EXAIR Super Blast Safety Air Gun model 1218.

Feeding the compressed air through an automatically closing ball valve, the 1218 removed the threat of unwanted flow from such a high force air gun.  The model 1218 also provides more than enough force and flow – the existing setup uses a 1-1/4” diameter orifice with a flow rate of 1986 SCFM (56,233 SLPM) with an unknown entrainment ratio; the 1218 has a flow rate of 460 SCFM (13,026 SLPM) with an entrainment ratio of 25:1, making the total directed flow equal to 11,500 SCFM (325,650 SLPM)!  This means the application can produce better or equal performance at a fraction of the compressed air consumption, thanks to the engineered design of EXAIR nozzles.  (See below for operational cost comparison.)

By converting to an EXAIR Super Blast Safety Air Gun this customer was able to add safety, increase performance, and lower operating costs.  If you have an application you think could benefit from better safety, performance, or operating cost, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

 

Compressed air costs are calculated as follows:

Previous setup:

1,986 SCFM compressed air consumption.  At a cost of $0.25/1000 SCF this equates to:

1,986 * ($0.25/1000) = $0.4965 for every minute of use

EXAIR model 1218:

460 SCFM compressed air consumption.  At the same cost of $0.25/1000 SCF this equates to:

460 * ($0.25/1000) = $0.115 for every minute of use

When comparing the two, the EXAIR model 1218 will provide an operational cost savings of almost 77%!

And, if you’re wondering how we determined the airflow through the existing setup, we used the charts below.

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Air calcs for the flow through a 1-1/4″ orifice