Tag: air pressure regulator

Common Compressed Air Drawing Symbols

Published on by John BallLeave a comment
The symbols on top denote the EXAIR products below (left to right): Flowmeter, Pressure Gauge, and Solenoid Valve

When it comes to drawings and diagrams to map out a process system, the piping and instrumentation diagrams (P&ID) are a great way to situate and find components.  They use different symbols to represent the types of products, the layout of the system, installation, and process flow.  These standard symbols are created by ANSI or ISO.  They are used in electrical, hydraulic, and pneumatic processes. I will cover some pneumatic symbols and the process flow in this blog.

A colleague, Russ Bowman, wrote an article about “Knowing Your Symbols Is Key To Understanding Your Drawings”.  As a reference, air compressors are the start of your pneumatic system, and there are different types as represented by the symbols below.

Air compressors are considered the fourth utility in industries because they use so much electricity, and they are inefficient.  So, you need to use the compressed air as efficiently as possible.  As a typical pneumatic system, the air compressors, receiver tanks and compressed air dryers would be on the supply side.  The distribution system, or piping, connects the supply side to the demand side.  This symbol is represented by a simple line.  The demand side will have many different types of pneumatic devices.  Since there are so many, ANSI or ISO has created some common types of equipment.  But if there isn’t a symbol created to represent that part, the idea is to draw a basic shape and mark it.

From top left, and then down: Automatic Drain Filter Separator, Oil Removal Filter, Pressure Regulator, and Super Air Knife

As an example, if I were to do a P&ID diagram of the EXAIR Super Air Knife Kit, it would look like the above diagram.  The kit will include the Super Air Knife with an Automatic Drain Filter Separator and a Pressure Regulator.  The Filter Separator is a diamond shape and, since it has an Automatic Drain, a triangle is placed at the bottom.  Filter Separators are used to clean the compressed air and keep the Super Air Knife clean.  The Automatic Drain will discard water and oil from the filter bowl when it accumulates over the float.  The next item is the pressure regulator, which is represented by a rectangle with an adjustment knob to “dial in” the desired blowing force.  And at the end, we drew a rectangle, which represents a Super Air Knife, as marked.

Using the P&ID diagram for the process flow is important.  You noticed that the Filter Separator would come before the Pressure Regulator.  This is significant when installing this system.  Did you remember the statement above about “using your compressed air as efficiently as possible”?  Inefficiencies come from two basic areas; pressure drop and overusing your compressed air.  Pressure drop is based on velocity.  The lower the velocity, the lower the pressure drop.  For the second part about overusing compressed air, the Pressure Regulator will help.  You want to use the lowest amount of air pressure as possible for the Super Air Knife to “do the job”.  The lower air pressure will use less compressed air in your operation.

EXAIR products are engineered to be safe, efficient, and effective in your compressed air system.  If you need help to place them in your P&ID diagrams, an Application Engineer can help you.  It is important to have the pneumatic devices in the proper place.  If you want to efficiently use your compressed air, you can use EXAIR products for your blow-off devices.  We have been doing this for a long time.

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

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.

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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Optimization:  Step 6 – Control the air pressure

Published on by John BallLeave a comment

Since air compressors use a lot of electricity to make compressed air, it is important that you use it as efficiently as possible.  EXAIR generated a chart with six simple steps to optimize your compressed air system.  Following these steps will help you to cut overhead costs and improve your bottom line.  In this blog, I will cover the sixth step; controlling the air pressure at the point of use.

Pressure Regulators

One of the most common pressure control devices is called the Regulator.  It is designed to reduce the downstream pressure that is supplying your system.  Regulators are commonly used in many types of applications.  You see them attached to propane tanks, gas cylinders, and of course, compressed air lines.  Properly sized, regulators can flow the required amount of gas at a regulated pressure for safety and cost savings.

EXAIR designs and manufactures compressed air products to be safe, effective, and efficient.  By replacing your “old types” of blowing devices with EXAIR products, it will save you much compressed air, which in turn saves you money.  But, why stop there?  You can optimize your compressed air system even more by assessing the air pressure at the point-of-use.  For optimization, using the least amount of air pressure to “do the job” can be very beneficial and practical.

Model 1100

Why are regulators important for compressed air systems?  Because it gives you the control to set the operating pressure.  For many blow-off applications, people tend to overuse their compressed air.  This can create excessive waste, overwork your air compressor, and steal from other pneumatic processes.  By simply turning down the air pressure, less compressed air is used.  As an example, a model 1100 Super Air Nozzle uses 14 SCFM of compressed air at 80 PSIG (5.5 bar).  If you only need 50 PSIG (3.4 bar) to satisfy the blow-off requirement, then the air flow for the model 1100 drops to 9.5 SCFM.  You are now able to add that 4.5 SCFM back into the compressed air system. And, if you have many blow-off devices, you can see how this can really add up.

In following the “EXAIR Six Steps To Optimizing Your Compressed Air System”, you can reduce your energy consumption, improve pneumatic efficiencies, and save yourself money.  I explained one of the six steps in this blog by controlling the air pressure at the point of use.  Just as a note, by reducing the pressure from 100 PSIG (7 bar) to 80 PSIG (5.5 bar), it will cut your energy usage by almost 20%.  If you would like to review the details of any of the six steps, you can contact an Application Engineer at EXAIR.  We will be happy to help. 

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