If you have been around compressed air systems, our blogs, or even optimized installations of point of use compressed air products, you will see point of use filtration in place. These filters come in a plethora of sizes, shapes, and specifications. Here at EXAIR we recommend to always keep a point of use filtration solution in place. This would include an auto-drain filter separator, as well as an oil removal filter.
Oil Removal Filters
So why do we have two instead of one? Could you use just the oil removal filter rather than two? Well, the answer lies in an optimized installation that will also carry with it a lower total cost of ownership. The auto-drain filter separators from EXAIR have a filter element which takes the air to a 5 micron level of filtration. (Except for the model 9004 which filters down to 20 micron.) The Oil Removal Filters have a coalescing filter element which filters to a 0.3 micron level for the finest debris/mists that may be contained within the compressed air stream. One reason for the separation is when a system is oil-free, the finer filtration level may not be needed. Also, by catching the bulk of material with the standard auto-drain filter and then leaving the finer filter to catch the residual amounts liquid that had been finely atomized within the stream of compressed air. This finer filter costs more so using it to catch larger particulate and risking it becoming clogged quicker will increase the total cost of ownership of the point of use compressed air product it is hooked to, hence never first and sometimes last. After the point of use filtration then placing the point of use pressure regulator and solenoid valves are next. This is all a better way to reduce risk of these being damaged from dirt and contaminants in the air lines. Total cost of ownership reductions all point to a better sustainability of any product.
To better showcase the importance of filtration, here’s a brief video I did a while back that visualizes just what one can see out of a compressed air line with minimal moisture introduced.
As you can see, keeping the point of use air filtered protects your process and decreases the total cost of ownership for your compressed air point of use product. If you would like to discuss other ways we can improve efficiency within your facility and help ensure you are getting the longest life out of your products, please contact us.
EXAIR has many options when considering Air Nozzles, Air Jets and Safety Air Guns. When considering the safety in using these tools one should consider the extra protection that EXAIR Safety Shields offer. Let’s look at the options and sizes of our Chip Shields.
EXAIR Chip Shields are durable polycarbonate shields that can be used with or without extension pipes. The Chip Shield, as the name suggests, protects the operator from flying debris such as metal chips, shavings and liquid coolants. The use of Chip Shields help meet the requirements of OSHA 1910.242(b) for safe use of compressed air.
If you are ordering a new Safety Air Gun from EXAIR and need a Chip Shield you simply place a “-CS” after the Safety gun model number, For example if you order Model 1210 VariBlast Compact Safety Air Gun (SAG) and want a Chip Shield you would order Model 1210-CS and EXAIR will automatically know the size of the shield and will ship the Safety Air Gun and properly sized Shield. If you would like the same gun with a 12″ extension you would order as such; 1210-12-CS and you will receive the Model 1210 VariBlast SAG with a 12″ Aluminum extension and Chip Shield.
If you have a SAG with an extension pipe and want to add or replace a Chip Shield then we must consider the extension pipe and nozzle NPT. All of the Chip Shields are the same size with the exception of the center diameter and the rubber grommet which will accommodate the NPT size of the Air Nozzle and extension. Here is a list of the replacement shields:
If you have a SAG and do not have an extension pipe or shield we have Chip Shield Kits that will allow you to retrofit your existing gun:
One important note is that SAG’s that are equipped with a Stay Set Hose will not allow for the Chip Shield to be installed. Choosing the correct Chip Shield or Retrofit Kit can be tricky but EXAIR Application Engineers are always ready to help. Please visit EXAIR.com and check out our informational site where ordering is easy.
Fluid mechanics is the field that studies the properties of fluids in various states. Fluid dynamics studies the forces on a fluid, either as a liquid or a gas, during motion. Osborne Reynolds, an Irish innovator, popularized this dynamic with a dimensionless number, Re. This number determines the state in which the fluid is moving; either laminar flow, transitional flow, or turbulent flow. For compressed air, Re < 2300 will have laminar flow while Re > 4000 will have turbulent flow. Equation 1 below shows the relationship between the inertial forces of the fluid as compared to the viscous forces.
Equation 1:
Re = V * Dh / u
Re – Reynolds Number (no dimensions)
V – Velocity (feet/sec or meters/sec)
Dh – hydraulic diameter (feet or meters)
u – Kinematic Viscosity (feet^2/sec or meter^2/sec)
To dive deeper into this, we will need to examine the boundary layer. The boundary layer is the area that is near the surface of the object. This could refer to a wing on an airplane or a blade from a turbine. In this blog, I will target pipes, tubes, and hoses that are used for transporting fluids. The profile across the area (reference diagram below) is a velocity gradient. The boundary layer is the distance from the wall or surface to 99% of the maximum velocity of the fluid stream. At the surface, the velocity of the fluid is zero because the fluid is in a “no slip” condition. As we move away from the wall, the velocity starts to increase. The boundary layer distance measures that area where the velocity is not uniform. If you reach 99% of the maximum velocity very close to the wall of the pipe, the air flow is turbulent. If the boundary layer reaches the radius of the pipe, then the velocity is fully developed, or laminar.
Boundary Layer Concept
The calculation is shown in Equation 2.
Equation 2:
d = 5 * X / (Re1/2)
d – Boundary layer thickness (feet or meter)
X – distance in pipe or on surface (feet or meter)
Re – Reynolds Number (no dimensions) at distance X
This equation can be very beneficial for determining the thickness where the velocity is not uniform along the cross-section. As an analogy, imagine an expressway as the velocity profile, and the on-ramp as the boundary layer. If the on-ramp is long and smooth, a car can reach the speed of traffic and merge without disrupting the flow. This would be considered Laminar Flow. If the on-ramp is curved but short, the car has to merge into traffic at a much slower speed. This will disrupt the flow of some of the traffic. I would consider this as the transitional range. Now imagine an on-ramp to be very short and perpendicular to the expressway. As the car goes to merge into traffic, it will cause chaos and accidents. This is what I would consider to be turbulent flow.
EXAIR Digital Flowmeter
In a compressed air system, similar things happen within the piping scheme. Valves, tees, elbows, pipe reducers, filters, etc. are common items that will affect the flow. Let’s look at a scenario with the EXAIR Digital Flowmeters. In the instruction manual, we require the meter to be placed 30 pipe diameters from any disruptions. The reason is to get a laminar air flow for accurate flow measurements. In order to get laminar flow, we need the boundary layer thickness to reach the radius of the pipe. So, let’s see how that number was calculated.
Within the piping system, high Reynold’s numbers generate high pressure drops which makes the system inefficient. For this reason, we should keep Re < 90,000. As an example, let’s look at the 2” EXAIR Digital Flowmeter. The maximum flow range is 400 SCFM (standard cubic feet per min). In looking at Equation 2, the 2” Digital Flowmeter is mounted to a 2” Sch40 pipe with an inner diameter of 2.067” (52.5mm). The radius of this pipe is 1.0335” (26.2 mm) or 0.086 ft (0.026m). If we make the Boundary Layer Thickness equal to the radius of the pipe, then we will have laminar flow. To solve for X which is the distance in the pipe, we can rearrange the terms to:
X = d * (Re)1/2 / 5 = 0.086ft * (90,000)1/2 / 5 = 5.16 ft or 62”
If we look at this number, we will need 62” of pipe to get a laminar air flow for the worse-case condition. If you know the Re value, then you can change that length of pipe to match it and still get valid flow readings. From the note above, the Digital Flowmeter will need to be mounted 30 pipe diameters. So, the pipe diameter is 2.067” and at 30 pipe diameters, we will need to be at 30 * 2.067 = 62”. So, with any type of common disruptions in the air stream, you will always get good flow data at that distance.
Why is this important to know? In many compressed air applications, the laminar region is the best method to generate a strong force efficiently and quietly. Allowing the compressed air to have a more uniform boundary layer will optimize your compressed air system. And for the Digital Flowmeter, it helps to measure the flow correctly and consistently. If you would like to discuss further how to reduce “traffic jams” in your process, an EXAIR Application Engineer will be happy to help you.
The pool is open, the garden is tilled, it must mean summer is coming. This year, I’m gearing up for a hot one. My love for spicy food is already well documented here on the EXAIR Blog, and this year it’s going to be the hottest one yet! In the garden for this year we have Purple Ghost Peppers, “regular” Bhut Jolokia (Ghost peppers), White Moruga Scorpion, Purple Ghost Scorpion, Bhutlah Scorpion, and a selection of “milder” peppers and other veggies for when I’d rather not melt my face off while eating. Needless to say, you should proceed with caution when eating salsa at my house. It’s going to be heating up in my kitchen at the same time your electrical cabinets also begin to overheat. Not to worry, EXAIR has the tools you need to keep things cool.
Some of what is in store for this year’s garden, acclimating to the “real’ sunshine in late April
EXAIR’sCabinet Cooler Systems were designed specifically to rectify these issues within your facility. Utilizing Vortex Tube technology, the Cabinet Cooler produces cold air from an ordinary supply of compressed air. This cold air keeps the enclosure free of debris and moisture and is easily installed in minutes through a standard electrical knockout. Here is a short video that shows just how simple it really is. The Cabinet Cooler Systems are available with Nema 12 (IP54) ratings and are also available in Aluminum, 303 Stainless Steel, and 316 Stainless Steel construction for Nema 4/4X (IP66) rated enclosures. For systems that are not able to be mounted on top of the cabinet, we also have Side Mount Kits available in Aluminum, 303 Stainless, and 316 Stainless. This year, EXAIR also introduced a new line of Hazardous Location Cabinet Coolers for use in classified areas.
Many of our customers experience seasonal overheating problems with their cabinets. Cabinet Cooler systems are a perfect solution for electrical panels which start to fault out in may or June and continue to cause chaos through September or October. They are quick to install, maintenance free and can be purchased with a thermostat control so they turn off in October and back on in May. You’ll hardly even remember its there and you won’t miss the electrical problems normally associated with a hot summer.
These systems are available with cooling capacities of anywhere from 275-5,600 Btu/hr. To make things much easier for you, we offer a Cabinet Cooler Sizing Guide that will allow us to recommend the most suitable model for your cabinet. With a few quick measurements, we’ll be able to determine the exact heat load that we’ll need to dissipate and offer you a quick and easy solution.
If you experienced heat related issues on electrical panels last year, or just want to talk about spicy food and gardening, contact an Application Engineer today and we’ll be happy to help. Don’t wait until it’s too late, EXAIR’s Cabinet Cooler is the simple solution for maintaining the temperature inside of your electronic enclosures.
