EXAIR not only has products that will reduce your air consumption, cost and noise levels but also has the tools to help you calculate the annual savings and Return on Investment (ROI). Sometimes you have the materials in house to make your own pneumatic tools so you get that piece of pipe in the maintenance crib, drill several holes and connect your compressed air. It works, your team is proud of the solution and everyone moves on to the next fire, right?
Several projects later you notice that your compressed air usage seems very high so a team is assembled and challenged with a cost savings program geared towards compressed air savings. EXAIR is the company that can help. We have Intelligent Compressed Air Products, Free Expert Technical Help and savings calculators that can be used to show the savings in your reports and presentations. EXAIR’s cost savings calculator will simplify the savings for each process you study and help your efforts in purchase justifications.
We have several examples of helping our customers save money such as this blog by one of our talented Application Engineers. You will realize more than cost savings as you should also see significant sound reductions and safety improvements as all of our products meet or exceed OSHA standard 29 CFR 1910.95 (a) which outlines allowable noise exposure for personnel and OSHA standard 29 CFR1910.242 (b) Dead End Pressure requirements.
When you begin compressed air cost savings program and have questions as to where to start, how to calculate and how to prepare your justifications please give EXAIR a call and talk with one of our many talented Application Engineers. EXAIR’s Intelligent Compressed Air products and Application Engineers will support all your efforts to decrease compressed air usage, reduce sound levels and increase the safety of your environment.
The Digital Flowmeter is available from stock for use on Schedule 40 pipe with sizes ranging from ½”-4” I.D. Sizes up to 8” for Schedule 40 and ¾”-4” for copper pipe are also available. Metric sizes are also available for 25mm, 40mm, 50mm, 63mm, 76mm, and 101mm. With a digital readout display, it’s easy to accurately monitor your compressed air usage throughout the facility. Creating a baseline of your usage will allow you to understand your compressed air demand, identify costly leaks, and replace inefficient air products.
The Digital Flowmeter installs in minutes with help from a drill guide and locating fixture to assist in mounting the Digital Flowmeter to the pipe. Two flow sensing probes are inserted into the drilled holes in the pipe. The meter then seals to the pipe once tightened. There is no need to cut, weld, or do any calibration once it is installed. With blocking rings also available, installation can be permanent or temporary. Below is a easy to follow video on how to install EXAIR’s Digital Flow Meter!
The newest addition to this product line is the Digital Flowmeter with wireless capability. Using a ZigBee® mesh network protocol, data is transmitted to an Ethernet connected gateway. This allows you to mount the Digital Flowmeter in areas that you may not be able to easily access and wirelessly monitor and graph the usage with the EXAIR Logger software. Take a peek at this video blog for a demonstration of the use of a wireless Digital Flowmeter software to compare an open pipe to an engineered Air Nozzle.
In addition to communicating wirelessly with the gateway, the Digital Flowmeters can “piggyback” off of each other to extend their range. Each meter has a range of 100’. Using multiple Digital Flowmeters within the same ZigBee® mesh network, data can be passed from meter to meter to extend the distance over which the meters can operate. These can be installed on each major leg of your compressed air system to continuously monitor usage throughout the facility.
If you’d rather go with a hard-wired data collection method, the Digital Flowmeter is also available with a USB Data Logger. Simply remove the Data Logger from the Digital Flowmeter and connect it to the USB port of your computer. The data can then be viewed directly in the accompanying software or exported into Microsoft Excel.
Two special flow meter options we now offer are the Pressure Sensing Digital Flowmeters, and the Hot Tap Digital Flowmeters!
Pressure Sensing Digital Flowmeters help by generating a pressure and consumption profile of a system can help to pinpoint energy wasters such as timer-based drains that are dumping every hour versus level based drains that only open when needed. Hot Tap Digital Flowmeters offer a way to install a flow meter on a pipe that is currently under pressure. It uses a series of valves and mufflers to maintain a safe working environment for the installer.
If you’d like to get a clear view of your compressed air usage, give us a call. An Application Engineer will be happy to work with you and get the proper Digital Flowmeters installed in your facility!
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.
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.
The calculation is shown in 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.
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.
When discussing ROI, return on investment, for an industrial compressed air system it is necessary to understand what it costs to produce compressed air. Generally we calculate that it costs .25 cents to produce 1,000 SCF (Standard Cubic Feet) of compressed air here in the Midwest of the United States. For our example let’s consider a typical 250 HP industrial compressor running 24 hours per day/5 days per week for 52 weeks. This compressor can generate 374,400,000 SCF per year, using the industry standard utility cost for the Midwest of .25 cents per 1,000 SCF it will cost $93,600 to produce that volume of compressed air.
To avoid wasting money on compressed air generation it is extremely important to eliminate unintended or wasteful compressed air use in your plant. The two main offenders are leaks and open tube blow-offs. While soapy water is a good method for discovering leaks, EXAIR offers the Ultrasonic Leak Detector. This handy device allows leaks to be detected at distances of up to 20′ away! Also consider how safe and convenient it is to find leaks in overhead pipes while standing on the ground instead of on a ladder. Using a tool like this to do an entire system leak audit can easily result in many small leaks being identified and when fixed result in a large savings.
Now let’s look at what an open pipe or tube may consume. A single 1/4″ OD copper tube can use 33 SCFM @ 80 PSIG inlet pressure. Using the manifold pictured above as our example with 13 open tubes, each tube can consume 33 SCFM @ 80 PSI inlet pressure. With 13 open tubes running 24 hours a day, 5 days a week, 52 weeks per year equates to a total consumption of 160,617,600 SCF annually. If we installed the EXAIR model 1100 Super Air Nozzle using a simple compression fitting we would reduce the air consumption dramatically. The EXAIR 1100 Super Air Nozzle consumes 14 SCFM @ 80 PSIG inlet pressure, running 24 hours a day, 5 days a week, 52 weeks per year equates to a total consumption of 68,140,800 SCF annually. That change will save you 92,476,800 SCF annually which is equal to $23,119.20 and 24.7% of air compressor capacity! These calculations are all based on continuous running applications, if intermittent operation is possible consider the EXAIR Electronic Flow Control for even greater savings. The EXAIR Electronic Flow Control combines a photoelectric sensor with timing control that limits compressed air use by turning it off when no part is present
Open pipe blow offs also violate OSHA standard 29 CFR 1910.242(b) requirement for using compressed air for cleaning when pressurized above 30 PSIG. Not to mention they generally are louder than 90 dBA, which is the maximum allowable noise exposure without hearing protection under OSHA standard 29 CFR – 1910.95 (a). The EXAIR engineered Super Air Nozzle is a great way to avoid a OSHA fine.
A great product that will help you keep your fingers on the pulse of compressed air consumption and demand is by incorporating the EXAIR Digital Flow Meter. This handy item mounts directly to the pipe. The digital display shows the amount of compressed air being used in any leg of your distribution system. The Digital Flow Meter is offered in sizes for 1/2″ – 4″ Schedule 40 Iron Pipe and 3/4″ – 4″ Copper Pipe. It also is available with the Summing Remote Display that is prewired with a 50′ cable, it is powered by the Digital Flow Meter and with a push of the button will display either the current compressed air consumption, consumption for the previous 24 hours or the total cumulative usage.
The Digital Flowmeters are also available with wireless capability using the ZigBee mesh network protocol, data can be passed from meter to meter to extend the distance over which the wireless system can operate. Each meter has a range of up to 100′ (30 meters). Or you can opt for the USB Data Logger option. The USB Data Logger can store approximately 9 hours of readings if set to sample once every second or up to 2 years if sampled every 12 hours.
If you would like to talk about any of the quiet EXAIR Intelligent Compressed Air® products or our line of Optimization Products, feel free to contact me or any EXAIR Application Engineer.
Russ Bowman, CCASS
Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook