Compressed Air Membrane Dryers: What are They? How do They Work?

A critical component on the supply side of your compressor system is the dryer. Atmospheric air contained within a compressed air system contains water vapor. The higher the temperature of the air, the more volume of moisture that air is capable of holding. As air is cooled, this water vapor can no longer be contained and this water falls out in the form of condensation. The temperature where this water will drop out is referred to as the dew point.

At a temperature of 75°F and 75% relative humidity, approximately 20 gallons of water will enter a 25HP compressor during a 24-hour period. As air is compressed, this water becomes concentrated. Since it’s heated during the compression process, this water stays in a vapor form. When this air cools further downstream, this vapor condenses into droplet form.

Moisture within the compressed air system can result in rust forming on the inside of the distribution piping, process failure due to clogged frozen lines in colder weather, false readings from instruments and controls, as well as issues with the point of use products installed within the system.

The solution to this problem is to install a dryer system. We’ve spent some time here on the EXAIR blog reviewing refrigerant dryers , desiccant dryersdeliquescent dryers, and heat of compression dryers. For the purposes of this blog, I’m going to focus on one of the newer styles on the market today: the membrane dryer.

Membrane Dryer

In a membrane dryer, compressed air is forced through a specially designed membrane that permits water vapor to pass through faster than the air. The water vapor is then purged along with a small amount of air while the rest of the compressed air passes through downstream. Generally, the dew point after the membrane dryer is reduced to about 40°F with even lower dew points also possible down to as low as -40°F!

With such low dew points possible, it makes a membrane dryer an optimal choice in outdoor applications that are susceptible to frost in colder climates. Membrane dryers also are able to be used in medical and dental applications where consistent reliability is critical.

A membrane dryer does not require a source of electricity in order to operate. The compact size makes it simple to install without requiring a lot of downtime and floor space. Since they have no moving parts, maintenance needed is minimal. Most often, this maintenance takes the form of checking/replacing filter elements just upstream of the membrane dryer. The membrane itself does need to be periodically replaced, an indicator on the membrane dryer will display when it needs to be changed. If particular instruments or processes in your facility are sensitive to moisture, a membrane dryer might be the best option.

However, there are some drawbacks to these types of dryers. They’re limited to low capacity installations, with models ranging from less than 1 SCFM up to 200 SCFM. This makes them more applicable for point-of-use installations than for an entire compressed air system. The nature in which the membrane dryer works necessitates some of the air to be purged out of the system along with the moisture. To achieve dew points as low as -40°F, this can equate to as much as 20% of the total airflow. When proper filtration isn’t installed upstream, oils and lubricants can ruin the dryer membrane and require premature replacement.

Make sure and ask plenty of questions of your compressor supplier during installation and maintenance of your system so you’re aware of the options out there. You’ll of course want to make sure that you’re using this air efficiently. For that, EXAIR’s wide range of engineered Intelligent Compressed Air Products fit the bill. With a variety of products available for same-day shipment from stock, we’ve got you covered.

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

EXAIR Celebrates Manufacturing Day With A Win For A Manufacturer

In 2012, the National Association of Manufacturers organized an effort to proclaim the first Friday in October (hey, that’s today!) as Manufacturing Day.  According to the Advanced Manufacturing National Program Office (a division of NIST, the National Institute of Standards & Testing,) the purpose of MFG Day is “to raise awareness among students, parents, educators and the general public about modern manufacturing and the rewarding careers available.”

Today is kind of a big deal around here.  Not only is EXAIR Corporation a manufacturer, but many of the companies that use our products are as well.  A lot of us have a rich story, woven into the cloth of the history of American manufacturing (which, in turn, is woven into the larger cloth of American history.)  Have you heard the one about the motivated inventor with an idea to make innovative products who started an operation out of his home that, with inspired direction & vision, became a worldwide leader in their industry?

Yeah; that’s us.  Today, we’re honoring Roy Sweeney’s legacy (he founded the company in October 1983,) and celebrating MFG Day, by publishing a new Case Study, proving out the benefits of the use of EXAIR Intelligent Compressed Air Products in regard to the monetary savings associated with the reduction in compressed air use, and the noise level reduction from the implementation of our engineered products.

You can download the complete Case Study here, but while we’re on the subject, here’s a basic rundown:

  • A roll forming operation used to blow off their product with a combination of loud and inefficient devices: copper tubing and modular flexible hose which is designed primarily for machine tool coolant, but often misapplied for use with compressed air.
  • It worked just fine, but an engineering study noted it as a potential wasteful use of compressed air.  That’s when they called us.
  • By replacing those blow offs with Model 1100 Super Air Nozzles and Model 1122 2″ Flat Super Air Nozzles, their noise levels dropped from 107 dBA to 83.8 dBA.  To put that in perspective, it went from the approximate sound level of a rock concert to that of a leaf blower. (ref: Centers for Disease Control & Prevention: What Causes Hearing Loss?)
  • Compressed air consumption dropped by more than half, from 190 SCFM to 86.8 SCFM…an annual savings of over $3,200.00.  All for an investment of $654.00 (2020 pricing) for those engineered Air Nozzles, Stay Set Hoses, and Magnetic Bases.  That means they’ll have paid for themselves in just under two months.
  • In addition to that, for participation in this Case Study, we’re giving them a generous credit on their order.  Happy Manufacturing Day!

And frankly, I think the engineered products just look better too.

Last but certainly not least, this reduction in compressed air usage decreases the load on their air compressors, reducing the electrical power consumed.  Product impact, along with our own consumption of resources and waste recycling, is a key component of EXAIR Corporation’s Sustainability Plan.  We’re making the world a better place, by making products that make the world a better place, using methods that make the world a better place.  I can’t think of a better way to celebrate Manufacturing Day.  If you want to get in on it, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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MFG Day logo courtesy of nist.gov

Are EXAIR’s Hoses and Tubes Right For You?

Are you tired of ducking and dodging hard pipe everywhere? Do you need something more mobile for your compressed air? Then EXAIR Hoses and Tubes might be a solution for you. EXAIR offers a variety of hoses and tubes in different styles designed to work with our products without affecting performance. These products simplify the use, setup, and integration of our various products into your process. Normally if you were to buy hoses you would need to determine the proper diameters, pressure ratings, and/or end fittings to best fit the item in use. This is all unnecessary when purchasing EXAIR’s Hoses and tubes for EXAIR products since everything is sized and properly rated to be used with our products. So, ask our Application Engineers if EXAIR Hoses and Tubes are right for you.

 Products may include the following.

Line Vac air operated conveyor hose
Conveying Hoses:

These hoses are used with our Air Operated Conveyors or Line Vacs which are used to convey material from point A to point B. The hose can be mounted on either side of the Line Vac using the properly sized hose clamp that comes with it. The Conveyance hose is made out of a durable PVC semi-flexible material in sizes from ¾” I.D. to 3” I.D. to match our Line Vac sizes. They also come in lengths up to 50’ in increments of 10’.

Coiled hose
Coiled Hoses:

When it comes to getting compressed air to our safety air guns, we offer a series of abrasion-resistant nylon Coiled Hoses. The coiled hose comes in a 12’ long length and comes in 3 sizes; these sizes are 1/8” NPT, ¼” NPT, and 3/8” NPT to attach right to EXAIR’s Safety Air Guns. The hoses also include swivel fittings to make for easier uncoiling. The coiled design makes it easy to reach around the work area and retract back to the substation. With the right size hose Coiled Hoses can supply the required amount of compressed air with minimal amount of pressure drop.

Compressed air hose
Compressed Air Hoses:

Compressed Air Hose can be used to reach equipment from overhead or near equipment. These hoses are made with synthetic rubber and comes in 3/8” I.D. and ½” I.D… Lengths up to 50’ long can be provided and the hoses are rated for up to 250 psig air pressure. These hoses can provide lasting protection from ozone, weathering and temperatures up to 158oF. They also come with two male ends in ¼” NPT or ½” NPT.

Stay Set Hoses
Stay Set Hoses:

Bendable and flexible, the stay set hose allows for manual positioning of your compressed air product. Equipped with “memory” function, the hose will not creep or droop until it is physically moved. The Stay Set Hose comes in lengths from 6” to 36” in length, and they offered in a combination of 1/8” and ¼” MNPT connections. These hoses are rated for 250 psig and are made of a reinforced rubber.

E-Vac Tubing

Vacuum Tubing:

When it comes down to our E-Vac product line, EXAIR offers vacuum tubing to be used along with the unit. This tubing is made from polyurethane and comes in 1/8” O.D. and 3/8” O.D. up to 50’ in length in increments of 10’.

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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OSHA 29 CFR 1910.95 (a) – It’s a Noise Exposure Standard, Not Just a Confusing Number

Strings of numbers and characters can often appear daunting.  For instance, if I wrote in binary code it would be a string of ones and zeros.  (01000101 01101110 01100111 01101001 01101110 01100101 01100101 01110010 01101001 01101110 01100111 00100000 01101001 01110011 00100000 01000001 01010111 01000101 01010011 01001111 01001101 01000101.) That can look like gibberish and cause concern if unknown or it can make sense to programmers and people familiar with binary code.

Other alphanumeric strings may cause some concern for industry professionals.  Take, for instance, OSHA standards. The OSHA standard 29 CFR 1910.95 (a) may be unfamiliar to some, and thus concerning. Many Environmental Health and Safety Engineers will recognize this code.  It is an OSHA standard that revolves around the amount of time an employee is permitted to be exposed to specific sound levels. These sound levels are all based on the weighted sound level of the noise the operators are exposed to. To better understand how the octave and frequency of the sound play into this, there is a chart provided below.

Equivalent A-Weighted Sound Level Chart – (1)

The weighted sound level is the level at which a Digital Sound Level Meter will read the current level of noise within an environment. This scale is then used to move further into the OSHA directive that we focus on helping companies meet to best provide safe environments for their employees to work in.

If you notice, the lowest weighted sound level is 90 dBA, this is also the lowest-rated noise level that OSHA speaks of in 1910.95(b)(2). It has been shown that noise levels over this level for extended periods will result in permanent hearing loss. The standard then goes on to discuss the duration an employee can be exposed to noise levels even with the use of personal protective equipment as well as even impulsive or impact noise.  The table of permissible time limits is shown below.

Permissible Noise Exposures (2)

As you can see from the table above provided by OSHA, any noise level that an operator is exposed to for eight hours cannot exceed 90 dBA. Noises within an industrial environment can also be variable throughout the day. For instance, the operator stands outside of a sheet metal press and the concussive strike on the press gives off a 90 dBA strike for every stroke of the press. This would not be a continuous noise level. Maybe the operator is operating a CNC machine that is cutting a nest of parts and uses a handheld blowgun to remove debris and coolant from the parts before taking them from their fixture. This blowgun is not used continuously and therefore would not be rated as such for the exposure time. A time study would be conducted on the average length of time the operator is utilizing this gun along with the level of noise it produces during use. OSHA then gives a calculation to use to appropriately combine the sound level while the gun is being used and when it is not in use. That equation is written out below.

Mixed Environment Exposure Fraction
C1/T1+C2/T2+… = ____
Total Exposure Fraction
Cn/Tn = ____

Where:
C1 = Duration of time for a specified noise level
T1 = Total time of exposure permitted at that level
Cn = Total time of exposure at a specified noise level
Tn = Total exposure time permitted at that level

Should the summation of the fractions for different exposures be greater than the Total Exposure fraction, the summation value should be used. As mentioned above, a time study on exposure to noise levels will be needed to obtain the information needed for this type of study. Once the study is done the process can proceed to the next level within the OSHA standard which is a hearing conservation program.

I would like to interject a small side-step at this point. Rather than rolling straight into the implementation of PPE which is proven to be the lowest reliable factor of protection by the CDC and NIOSH. If any of these noise levels being generated are due to the use of compressed air points of use, EXAIR can potentially lower the noise of these point of use applications. In the events, open blowoffs or “band-aid” fixes are in place to keep processes running, and Engineered Solutions can easily be implemented that will reduce the noise level produced by this operation. Whether it is on the handheld Safety Air Gun in the hands of a CNC operator, or if it is a part/scrap ejector that is blowing the sheet metal press out after every strike, we have products that have proven time over time using an Engineered Solution will save air, reduce noise levels, and still get the job done.

If you would like to discuss OSHA directives revolving around compressed air, share with us a recent citation you received from an inspector for this standard, or just discuss compressed air usage in general, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

1 – Equivalent A-Weighted Sound Level Chart – Retrieved from OSHA.Gov – https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9735&p_table=standards

2 – Permissible Noise Exposures – Retrieved from OSHA.Gov – https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9735&p_table=standards