Recently, EXAIR Application Engineers have written blogs about reciprocating type air compressors: Single Acting (by Lee Evans) and Dual Acting (by John Ball.) Today, I would like to introduce you, dear EXAIR blog reader, to… More
A casting company used a die casting process to make large aluminum panels. In their operation, a two-part die would clamp together and be filled with hot liquid aluminum. Once the panel was formed and cooled, the die would open to release the part. Before the next panel was die casted, they would use a home-made cart to cool and clean the dies. The cooling was done first by spraying water onto the surface, then compressed air was used to dry the dies. When they started to use their home-made cart in their process, they noticed that the air pressure would begin to drop in their facility. Other locations in the plant started having problems with their pneumatic equipment. They were using too much compressed air during the drying period; so, they contacted EXAIR to see if we could help reduce the amount of compressed air to dry the dies.
To explain a little more about the home-made cart, it was made from a 1” square piece of tubing that was bent in a U-shape. The dimension of the cart was about 40” long and 24” high. Across the top was a piece of extruded aluminum spanning the two ends of the U-shape tubing. This portion of the cart would supply the water to the liquid nozzles. The liquid nozzles hung vertically down from the extruded aluminum at designated heights to target certain areas of the dies. The U-shaped square tubing was used to supply the compressed air to the blow-off nozzles. The compressed air inlets were welded onto each end of the 1” square tubing. Across the bottom of the cart, the 1” square tubing had 38 holes that were drilled and tapped to 1/8” NPT (19 tapped holes on each side). The blow-off nozzles were 1/8” pipes with the ends smashed (reference picture below). They were made to different lengths to get as close to the die for maximum blowing force. The entire home-made assembly was attached to a robotic fixture with a cam to move the large cart between the dies. In applications using “smashed” pipes, they are very easy and inexpensive to make. But, as this customer found out, they use way too much compressed air and they are not as effective in blowing-off or drying.
The customer above was limited to modifications to the home-made cart. It was already configured with the robot features and cam to hit the targeted areas. So, I recommended the model HP1126, 1” High Power Flat Super Air Nozzle. It has a 1” wide air stream that is very similar to the flow pattern of the 1/8” smashed pipe. But unlike the smashed pipe design, the model HP1126 nozzle can accomplish so much more. One of the biggest differences is that the EXAIR nozzles use much less compressed air. (The initial reason for contacting EXAIR). With the engineered design of the nozzle, it can entrain large amounts of ambient air which means that less compressed air is required. For a 1/8” NPT smashed pipe, it can use close to 70 SCFM of air at 80 PSIG – each!
The model HP1126 only requires 17.5 SCFM at 80 PSIG. That is a difference of 52.5 SCFM per nozzle. With 38 nozzles being used on this home-made cart, that equates to a total savings of 1,995 SCFM of compressed air. By simply replacing the 1/8” smashed pipe to a model HP1126 with a shorter nipple, their facility was able to save much compressed air and maintain the pneumatic requirements in the other work areas.
The customer was extremely happy with the air savings, but they asked about the amount of force that the model HP1126 can supply. It was important in their process to remove any residual water from the dies. The reason for the blow-off pipes to be so close to the die was to try and increase the blowing force. The best way that I could explain to them was by using an example of a garden hose. (Reference a blog by Neal Raker “Sometimes Back Pressure is Good; Sometimes it is Bad“). The garden hose is attached to a spigot outside your house. As you open the spigot to supply water through the hose, the water will flow out of the hose at a slow velocity; not very strong. When you place your thumb partially over the end of a garden hose, you restrict the flow and increase the force. Now, you can reach the second-floor windows of your house to clean. With a lack of restriction at the end of the pipes, the air pressure will drop quickly as it travels through the long square tube and through the 1/8” pipe extensions. By the time the compressed air reaches the blow-off site, the pressure is much lower; thus, reducing the effectiveness of removing the water.
The EXAIR nozzles work like your thumb on the hose. The usable pressure is increased at the HP1126 nozzle, instead of a point much further upstream. By increasing the pressure at the point-of-use, the effective velocity and force is much stronger. In addition to this, they can now move the nozzles away from the die surface; in case of any “hiccups” in moving the cart in and out of the dies and eliminating any marring of the surfaces.
Once they installed the 38 pieces of the model HP1126 nozzles onto their cart, the first thing that they noticed was the amount of noise reduction. The model HP1126 only has a noise level of 82 dBA at 80 PSIG, compared to a noise level of an open pipe which is over 100 dBA. By replacing the flattened nozzles with the EXAIR nozzles, this company was able to…
1. reduce air consumption
2. keep the other areas of the plant operating by conserving compressed air at this location
3. reduce the noise level and
4. increase the effective blowing force
If you find that by using your blow-off/drying system, your pneumatic machines under-perform, or the low-pressure alarms are triggered, or you have to turn on an auxiliary compressor, you should contact an Application Engineer at EXAIR to see if we can optimize your compressed air devices. These EXAIR engineered nozzles can remove many issues in your system as it did with the casting company above.
I wrote a blog a few weeks ago about increasing efficiency with EXAIR Super Air Nozzles. In the application for that blog we used engineered nozzles to place open pipes, resulting in an efficiency increased of ~65%. This week’s installment of efficiency improvements boasts similar figures, but through the replacement of misused liquid nozzles rather than open pipe.
The image above shows a compressed air manifold with a number of nozzles. BUT, the nozzles in this manifold are not compressed air nozzles, nor do they have any engineering for the maximization of compressed air consumption. These are liquid nozzles, usually used for water rinsing.
In this application, the need was to blow off parts as they exit a shot blasting machine. When the parts exit the shot blasting process they are covered in a light dust and the dust needs to be blown away. So, the technicians on site constructed the manifold, finding the liquid nozzles on hand during the process. They installed these nozzles, ramped up the system pressure to maintain adequate blow off, and considered it finished.
And, it was. At least until one of our distributors was walking through the plant and noticed the setup. They asked about compressed air consumption and confirmed the flow rate of 550 m³/hr. (~324 SCFM) at 5 BARG (~73 PSIG).
The end user was happy with the performance, but mentioned difficulty keeping the system pressure maintained when these nozzles were turned on. So, our distributor helped them implement a solution of 1101SS Super Air Nozzles to replace these inappropriately installed liquid nozzles.
By implementing this solution, performance was maintained and system pressure was stabilized. The system stabilization was achieved through a 61% reduction in compressed air consumption, which lessened the load on the compressed air system and allowed all components to operate at constant pressure. Calculations for this solution are shown below.
Existing compressed air consumption: 550 m³/hr. (324 SCFM) @ 6 BARG (87 PSIG)
Compressed air consumption of (9) model 1101SS @ 5.5 BARG (80 PSIG): 214 m³/hr. (126 SCFM)
Total compressed air consumption of 1101SS Super Air Nozzles:
Air consumption of 1101SS nozzles compared to previous nozzles:
Engineered air nozzles saved this customer 61% of their compressed air, stabilized system pressure, improved performance of other devices tied to the compressed air system, and maintained the needed performance of the previous solution. If you have a similar application or would like to know more about engineered compressed air solutions, contact an EXAIR Application Engineer.
I had the pleasure of discussing a spot cooling application with a customer this morning. He wanted to get more flow from his Adjustable Spot Cooler, but still keep the temperature very low. He machines small plastic parts, and he’s got enough cold flow to properly cool the tooling (preventing melting of the plastic & shape deformation) but he wasn’t getting every last little chip or piece of debris off the part or the tool.
After determining that he had sufficient compressed air capacity, we found that he was using the 15 SCFM Generator. The Adjustable Spot Cooler comes with three Generators…any of the three will produce cold air at a specific temperature drop; this is determined only by the supply pressure (the higher your pressure, the colder your air) and the Cold Fraction (the percentage of the air supply that’s directed to the cold end…the lower the Cold Fraction, the colder the air.)
Anyway, the 15 SCFM Generator is the lowest capacity of the three, producing 1,000 Btu/hr of cooling. The other two are rated for 25 and 30 SCFM (1,700 and 2,000 Btu/hr, respectively.)
He decided to try and replace the 15 SCFM Generator with the 30 SCFM one…his thought was “go big or go home” – and found that he could get twice the flow, with the same temperature drop, as long as he maintained 100psig compressed air pressure at the inlet port. This was more than enough to blow the part & tool clean, while keeping the cutting tool cool, and preventing the plastic part from melting.
If you’d like to find out how to get the most from a Vortex Tube Spot Cooling Product, give me a call.
Drilled pipes, like the one shown above, are all too common in industrial settings for processes where a wide surface area needs to be treated. Their popularity can be attributed to how cheap and easy they are to make but in actuality they are very expensive to operate, as they waste large amounts of compressed air, and are very dangerous to operate.
We frequently take calls from customers looking for a more energy efficient, safer solution to replace these types of blowoffs. EXAIR manufactures 3 different styles of Air Knife – the Super, Standard and Full-Flow – that are the ideal solution for wide coverage applications. Today, I would like to provide an overview of our award wining Super Air Knife.
The Super Air Knife is our most efficient air knife in regards to compressed air usage, using only 2.9 SCFM per inch of knife length @ 80 PSIG. It is also the quietest on the market today at only 69 decibels. The Super Air Knife provides the highest air velocity of the 3 styles offered by EXAIR and produces 2.5 ounces of force per inch at 80 PSIG operating pressure. We offer stock lengths from 3” up to 108” in single piece construction with available materials of aluminum, 303ss and 316ss. We also offer PVDF (Polyvinylidene Fluoride) up to 54” for harsh environments.
The Super Air Knife provides a laminar airflow across the entire length with hard-hitting force. They also give a 40:1 amplification rate meaning they entrain 40 parts of the surrounding room air for every 1 part of compressed air used, producing a large volume outlet flow.
For applications requiring an air knife length longer than 108″, we offer a coupling bracket kit that allows you to connect two Super Air Knives together for a seamless, uninterrupted flow. Kits are available in aluminum, 303ss or 316ss to match the construction of the knife.
In addition, we also offer plumbing kits as an accessory item. For aluminum Super Air Knives, we offer cut to length nitrile/PVC hose and brass fittings and for stainless steel and PVDF knives we offer 316ss cut-t0-length pipe and fittings.
If you have any questions on how the Super Air Knife might fit into your process, please contact an Application Engineer.
It’s a good question. When do you know that your compressed air system is complete? And, really, when do you know, with confidence, that it is ready for use?
A compressor or compressed air source, is just as it sounds. It is the device which supplies air (or another gas) at an increased pressure. This increase in pressure is accomplished through a reduction in volume, and this conversion is achieved through compressing the air. So, the compressor, well, compresses (the air).
A control receiver (wet receiver) is the storage vessel or tank placed immediately after the compressor. This tank is referred to as a “wet” receiver because the air has not yet been dried, thus it is “wet”. This tank helps to cool the compressed air by having a large surface area, and reduces pulsations in the compressed air flow which occur naturally.
The dryer, like the compressor, is just as the name implies. This device dries the compressed air, removing liquid from the compressed air system. Prior to this device the air is full of moisture which can damage downstream components and devices. After drying, the air is almost ready for use.
To be truly ready for use, the compressed air must also be clean. Dirt and particulates must be removed from the compressed air so that they do not cause damage to the system and the devices which connect to the system. This task is accomplished through the filter, after which the system is almost ready for use.
To really be ready for use, the system must have a continuous system pressure and flow. End-use devices are specified to perform with a required compressed air supply, and when this supply is compromised, performance is as well. This is where the dry receiver comes into play. The dry receiver is provides pneumatic capacitance for the system, alleviating pressure changes with varying demand loads. The dry receiver helps to maintain constant pressure and flow.
In addition to this, the diagram above shows an optional device – a pressure/flow control valve. A flow control valve will regulate the volume (flow) of compressed air in a system in response to changes in flow (or pressure). These devices further stabilize the compressed air system, providing increased reliability in the supply of compressed air for end user devices.
Now, at long last, the system is ready for use. But, what will it do? What are the points of use?
Points of use in a compressed air system are referred to by their end use. These are the components around which the entire system is built. This can be a pneumatic drill, an impact wrench, a blow off nozzle, a pneumatic pump, or any other device which requires compressed air to operate.
If your end use devices are for coating, cleaning, cooling, conveying or static elimination, EXAIR Application Engineers can help with engineered solutions to maximize the efficiency and use of your compressed air. After placing so much effort into creating a proper system, having engineered solutions is a must.
Intelligent Use of Compressed Air – Most industrial facilities have at least one air compressor. The compressor is used to power anything from pneumatic tools, air powered equipment, compressed air cylinders, blowoffs and many more types of operations. Improper use of compressed air can lead to unnecessary energy costs, high noise levels and dangerous exposure of personnel to high pressure air.
The EXAIR Super Air Knife uses only 1/3 of the compressed air of typical blowoffs.
By taking advantage of the Super Air Knife’s highly efficient design and the action of air entertainment, the Super Air Knife draws in large amounts of surrounding free outside air into the air stream. The result is a strong powerful air flow made up of a small amount of compressed air and a large amount of ambient air.
- Compressed air flows through an inlet (1) into the plenum chamber of the Super Air Knife. The flow is directed to a precise slotted orifice. As the primary airflow exits the thin slotted nozzle (2), it follows a flat surface that directs the airflow in a perfectly straight line. This creates a uniform sheet of air across the entire length of the Super Air Knife. Velocity loss is minimized and force is maximized as room air (3) is entrained into the primary air stream at a ratio of 40:1. The result is a well defined sheet of laminar airflow with hard-hitting force and minimal wind shear is delivered.
By using a Super Air Knife – and the advantage of the high amplification via air entertainment – for part blowoff, cooling, or drying you can reduce energy costs, reduce noise levels, and eliminate harmful dead end pressures. Other air knives typically entrain surrounding air at a ratio of 30:1 or less.
EXAIR offers the Super Air Knife with materials of construction of aluminum, Types 303 and 316 Stainless Steel, and PVDF to cover a wide variety of application temperatures and environments. Other materials may be possible, pending review by our Product Design Engineers. The Super Air Knives are offered as the knife only, as part of a full kit, which also includes a shim set, auto drain filter separator, and pressure regulator. The Super Air Knife can be fitted with Plumbing Kits and/or Electronic Flow Control making installation easier and help to save on air usage.
If you have questions about Super Air Knives, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
What is Air? Air is an invisible gas that supports life on earth. Dry air is made from a mixture of 78% Nitrogen, 21% Oxygen, and 1% of remaining gases like carbon dioxide and other inert gases. Ambient air contains an average of 1% water vapor, and it has a density of 0.0749 Lbs./cubic foot (1.22 Kg/cubic meter) at standard conditions. Air that surrounds us does not have a smell, color, or taste, but it is considered a fluid as it follows the rules of fluid dynamics. But unlike liquids, gases like air are compressible. Once we discovered the potential of compressing the surrounding air, we were able to advance many technologies.
Guess when the earliest air compressor was used? Believe it or not, it was when we started to breathe air. Our diaphragms are like compressors. It pulls and pushes the air in and out of our lungs. We can generate up to 1.2 PSI (80 mbar) of air pressure. During the iron age, hotter fires were required for smelting. Around 1500 B.C., a new type of air compressor was created, called a bellows. You probably seen them hanging by the fireplaces. It is a hand-held device with a flexible bag that you squeeze together to compress the air. The high stream of air was able to get higher temperature fires to melt metals.
Then we started to move into the industrial era. Air compressors were used in mining industries to move air into deep caverns and shafts. Then as the manufacturing technologies advanced, the requirements for higher air pressures were needed. The stored energy created by compressing the air allowed us to develop better pneumatic systems for manufacturing, automation, and construction. I do not know what the future holds in compressed air systems, but I am excited to find out.
Since air is a gas, it will follow the basic rules of the ideal gas law;
PV = nRT (Equation 1)
P – Pressure
V – Volume
n – Amount of gas in moles
R – Universal Gas Constant
T – Temperature
If we express the equation in an isothermal process (same temperature), we can see how the volume and pressure are related. The equation for two different states of a gas can be written as follows:
P1 * V1 = P2 * V2 (Equation 2)
P1 – Pressure at initial state 1
V1 – Volume at initial state 1
P2 – Pressure at changed state 2
V2 – Volume at changed state 2
If we solve for P2, we have:
P2 = (P1 * V1)/V2 (Equation 3)
In looking at Equation 3, if the volume, V2, gets smaller, the pressure, P2, gets higher. This is the idea behind how air compressors work. They decrease the volume inside a chamber to increase the pressure of the air. Most industrial compressors will compress the air to about 125 PSI (8.5 bar). A PSI is a pound of force over a square inch. For metric pressure, a bar is a kg of force over a square centimeter. So, at 125 PSI, there will be 125 pounds of force over a 1” X 1” square. This amount of potential energy is very useful to do work for pneumatic equipment. To simplify the system, the air gets compressed, stored as energy, released as work and is ready to be used again in the cycle.
Compressed air is a clean utility that is used in many different applications. It is much safer than electrical or hydraulic systems. Since air is all around us, it is an abundant commodity for air compressors to use. But because of the compressibility factor of air, much energy is required to create enough pressure in a typical system. It takes roughly 1 horsepower (746 watts) of power to compress 4 cubic feet of air (113L) to 125 PSI (8.5 bar) every minute. With almost every manufacturing plant in the world utilizing compressed air in one form or another, the amount of energy used to compress air is extraordinary. So, utilizing compressed air as efficiently as possible is mandatory. Air is free, but making compressed air is expensive
If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Products, you can contact an Application Engineer at EXAIR.