Tag: regulator

Pressure Drop vs Differential Pressure

Published on by John BallLeave a comment

I find myself interchanging these terms; pressure drop and differential pressure.  This is very common as both are determined by the change in pressure between two points.  In this blog, I will cover the difference between these two terms in my view.

Pressure drop only occurs when the air is flowing.  The higher the velocity, the more extreme the pressure drop will be.  Velocity is created when the pressure changes.  So, the higher pressure will go toward the lower pressure.  But we wish for that pressure difference to be as low as possible.  Pressure drop is always a loss, and you cannot regain that energy.  Forms of pressure drop that can be found are like small diameter pipes or tubing; restrictive fittings like quick disconnects, and conditioning equipment like after coolers and air dryers.  If too large of a pressure drop occurs, the pneumatic equipment will not have enough power to operate effectively and efficiently.  I have another blog with a video that helps demonstrate this, “Pressure Drop and its Relationship to Compressed Air”. 

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Differential pressure can be static or flowing.  It is very similar to pressure drop except that the energy is stored.  The most common device that does this is the pressure regulator.  You are able to reduce the pressure downstream to the point-of-use.  This type of pressure reduction stores energy, and it will save you money, instead of wasting money.  For every 10 PSI reduction in pressure, it will save you 5% in energy.  With blow-off devices, you want to use the least amount of pressure to “do the job”.  Over-using your compressed air is wasteful.

Here is a graph of a typical compressed air system.  As you can see, the typical pressure drop from the air compressor to the point-of-use.  So, if you can reduce the pressure drop through the system and optimize the differential pressure from the regulator to your point-of-use, you can optimize your system.

Pressure Drop Chart

In a simple statement, a pressure drop loses energy while differential pressure stores energy for later use.  EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side.  This will include the EXAIR Super Air Knives, Super Air Nozzles, and Safety Air Guns.  If you wish to go further in optimizing your system, an Application Engineer at EXAIR will be happy to help you.

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

Pressure Drop Chart by Compressed Air Challenge Organization.

“Under Pressure” Pressure Regulators!

Published on by Jordan T ShouseLeave a comment

I recently recommended to a customer to turn their air pressure down on their system as low as their process would allow. Meaning regulate the pressure so you have enough to complete the operations needed but find that happy medium where your compressor isn’t working as hard to build those high pressures for no reason!

Compressed air is an amazing tool to have, and when used properly it can be more efficient that other non-compressed air tools that run off electricity. However, it’s pretty common to see compressed air systems running at their max just because.

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Lowering the air system pressure reduces the compressor power consumption by about 1% for every two psi of lower pressure. Lowering the pressure also makes any unregulated operations reduce consumption by almost 1% for every one psi of pressure reduction. Not to mention the extra savings if your compressor system can turn down the compressor power because of the reduced flow and possibly shut off compressors that are no longer needed!

The best pressure at which to set your system is the level where your production can operate efficiently and effectively without waste: There is no right pressure—it depends on your operations and tools. You may have 90 to 100 psig at the compressor, but at the production machine, where the actual work is being done, you could have only 65 to 70 psig. In some cases, it may be even lower due to pressure drops in undersized piping, filters, regulators. The goal is to lower compressor discharge pressure without affecting the the operations at the end of the line.

Having artificially high plant-pressure can help you deal with surges in compressed air demand that might occasionally cause low-pressure and affect production. The higher pressure acts to store reserve air in the various volumes made up of receivers, pipes and such in your system. However, the higher pressure costs more to produce and makes unregulated end uses consume more air, which is an expensive trade-off. Another option is to make sure you have line pressure regulators at each point of use. This will allow you to regulate the operation to the pressure needed being sure to save compressed air and keep the over all system running more efficient.

You can regulate those point of use lines with a number of EXAIRs Pressure Regulators!

EXAIR offers a range of Pressure Regulators capable of handling air flow of up to 700 SCFM.

If we can help size a regulator, or have any other questions on how EXAIR can help you save compressed air in your system please reach out to me or one of our other Application Engineers!

Jordan Shouse
Application Engineer

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What OSHA 1910.242(b) Means For Compressed Air Product Users

Published on by Russ BowmanLeave a comment

Medically speaking, our skin is an organ…and an amazing one at that. It protects our internals from an incredibly harsh environment as we’re bombarded by radiation (sunlight), subjected to summer’s heat & the cold of winter, attacked by fierce invaders (from viruses & bacteria to insects & spiders), all while we carry on at the bottom of a 60 mile-deep ocean (of air!)

Our skin requires some protection too: Sunscreen mitigates some of the harmful effects of solar radiation, shoes protect our feet from the ground, gloves & coats prevent frostbite, and compliance with OSHA Standard 1910.242(b) protects operators who use compressed air devices for cleaning purposes from air embolisms. That’s when air, under pressure, has enough energy to break the skin (tough as it is) and reach the tissue underneath. It’s painful, and serious enough that the victim should absolutely seek emergency medical treatment. If the air breaks a blood vessel and enters the pulmonary system, it can be deadly, in a hurry.

In 1971, the U.S. Occupational Health and Safety Administration (OSHA) determined that air under pressure higher than 30 pounds per square inch is capable of causing such injuries, if the pressurized source is dead-ended into the skin. Based on this determination, they included the following verbiage in Standard 1910.242, regulating the safe operation of hand and portable powered tools & equipment:

1910.242(b) Compressed air used for cleaning. Compressed air shall not be used for cleaning purposes except where reduced to less than 30 p.s.i. and then only with effective chip guarding and personal protective equipment.

In February 1972, OSHA issued Instruction STD 01-13-001 to clarify the meaning of 1910.242(b), with two illustrations of acceptable methods to meet compliance. The first is the use of a pressure reducer (or regulator):

While this method is compliant with the OSHA Standard, it’s kind of impractical, since you’re not going to get a whole lot of cleaning done with such a low energy air flow. If that’s not bad enough, it’s STILL going to be loud, and wasteful as far as the cost of compressed air goes.

The other method illustrated in the Instruction’s enclosures involves the nozzles themselves:

Compressed air product manufacturers use this method to make OSHA compliant Nozzles.

One design that complies with OSHA 1910.242(b) using this method is the cross drilled nozzle:

Unless it’s blocked off, practically all of the air flow goes straight out the end, but if you block off the end, it all goes out the cross drilled hole. As long that hole is properly sized, you won’t build up 30 psi at the main outlet.

If you’re not concerned about high operating cost or deafening noise, you can stop reading now; these are all you need for OSHA compliance with Standard 1910.242(b). If you DO care about spending less money on compressed air or complying with OSHA Standard 1910.95(a) (which you read all about here), let’s spend a minute on engineered compressed air nozzles:

EXAIR Super Air Nozzles discharge compressed air through an annular array of holes, recessed between a series of fins. This causes the primary (compressed air) stream to entrain an enormous amount of air from the surrounding environment.

In addition to making them cost less to operate (since most of the total developed air flow is entrained), they’re also VERY quiet (since the entrained air forms a boundary layer on the outside of the air stream), AND they can’t be dead ended:

Since the fins won’t allow for a complete blockage of the compressed air discharging from the Super Air Nozzle, this design is a prime example of a built-in “relief device” as defined by Instruction STD 01-13-001, above.

All EXAIR Intelligent Compressed Air Products, in fact, incorporate a form of built-in “relief device”:

The overhang of the cap on the Flat Super Air Nozzles and the Super Air Knives prevent them from being dead ended.

If you’d like to discuss safe use of compressed air, it’s one of our primary goals here at EXAIR – give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR LLC
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Pressure Regulators

Published on by exaircorpLeave a comment

At EXAIR, a large part of my job is to discuss your applications and make recommendations based upon which of our products would best help your application. In doing so, we always review your air supply to ensure that you have enough air to run our products. For instance you may need an Air Nozzle. This seems simple enough right? Surely you have enough air for this? Well, if you are buying our Atto Super Air Nozzle (left) you probably do, as this is a small nozzle that consumes 2.5 SCFM. However, you may need our large Super Air Nozzle Cluster (right) that will consume 168 SCFM. So as you can see it’s important that we discuss the amount of air you have at the point of use.

Another part of my job is to help customers trouble shoot issues once they have installed our products. I can proudly say that rarely is it an issue with the product itself. The most common cause of malfunction is with the air supply at the point of use. I have seen companies with massive air compressors not be able to supply 30 SCFM. Why? Well just because you have a lot of air coming out of the compressor, doesn’t mean you have a lot of air at the point of use. Other machines and tools down the line, as well as leaks and turns may have depleted the air supply long before it reaches your station for this application. This is the reason why we always recommend our Pressure Regulators with Gauge as seen here:

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

It’s pretty obvious why we would want you to have a gauge at the point of use, but the importance of the pressure regulator is many times overlooked. Many of our products need to have a certain pressure of air along with the proper SCFM to function efficiently. Some of these are products include some of our Industrial Housekeeping Products and Cabinet coolers. But, many of our products will function perfectly, and even be more efficient for your application with less airflow and psi. To find the best pressure and flow, we use a rule of thumb of starting at 80 psig and dial it back (or up) 5 psig at a time, until the best fit is found.

Most facilities have airlines running throughout, and they are all pushing the same psi and airflow. It is easy to just tap in and drop a line to the new point of use for the new tool. But, if there are 10 machines in line before this one, the air supply at machine 1, is much more than at machine 10. There are also leaks, turns, buildup in the line, and other air flow restrictions that are most likely in the way… This is why you will need a gauge and a pressure regulator at each point of use…

Also, when you drop a line to run a Super Air Knife (or any other EXAIR product) it may be coming off of a 100 psig line. You may only need 40 psi to run this 12″ Super Air knife. At 40 psig you will be pushing 21 SCFM. If this can clean, dry, or move your material as needed, then why use the 100 psig coming from the shop line? At 100 psig, that same 12″ Super Air Knife will use 42 SCFM. That additional SCFM has a rough cost of about $10 per day (running 24 hrs day with cost per kWh at $0.10). As you can see from this simple example, the pressure regulator is a no brainer to save costs and increase efficiency in the product itself.

There are many blogs written about your compressed air being the 3rd to 4th highest utility expense for many companies. In todays economic climate, it is important to use every efficiency possible. Using a regulator is imperative to control any type of flow, be it water, gas, electricity and even – air. Please give us a call to discuss any questions with your next application.

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
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