Sound levels are an important safety consideration in most industrial facilities. OSHA has guidelines on allowable noise levels and exposure, covered in OSHA Standard 29CFR – 1910.95 (a). Sound levels are measured in decibels, or dB. It makes sense that a higher decibel value means a louder sound (as illustrated in the graphic below). What is not intuitive is how multiple sound levels interact and combine, or how they compare to one another.
The first thing to understand about sound levels is that they aren’t measured on a linear scale. Instead, they’re measured on a logarithmic scale. This can really throw off our intuition. For instance, a sound at 20dB is actually 10 times stronger than one at 10dB, and a sound at 30dB is 100 times stronger than 10dB. If it were a linear scale, 20dB and 30dB would only be 2 and 3 times stronger than 10dB, similar to how mass works—like 20kg being double the mass of 10kg.
You can see why this is the case with the formula for calculating sound levels, which is as follows:
It’s important to note that the sound pressure levels calculated using this formula are unweighted. To really grasp how loud something will seem to us, we have to consider how our ears pick up various frequencies. This means that low and extremely high frequencies are given less weight than on the standard decibel scale. This adjusted measurement is referred to as dBA. You can check out some typical sounds and their dBA levels in the chart below:
Because of this logarithmic scale, combining two sounds can be pretty counter-intuitive too. Our Model 1100 Super Air Nozzle generates a sound level of 74 dBA, but when you place two of them side by side, the sound level jumps to 78 dBA (and not 148dBA). This is determined using the formula below:
The specifics of this calculation are explained in this blog here, but OHSA provides a quick and easy way to calculate, as shown in the table below:
To see if you need to tackle the noise levels in your facility, you should start by taking a baseline measurement of the different processes and devices that are making the noise. EXAIR’s Sound Level Meter, Model 9104, is here to help. It’s super user-friendly and gives you a digital readout of the sound level (no need to deal with logarithms!).
If you would like to discuss sound levels in your facility, or any of your other compressed air needs, give us a call!
Compressed air serves as the essential utility for operation, and its performance limitations are determined by the supply available. To effectively utilize EXAIR products and pneumatic equipment, it is crucial to establish a method for transferring compressed air from the source to the point of use. This can be accomplished through three primary means: pipes, hoses, and tubes.
As compressed air travels through the distribution system, it experiences friction against the inner surfaces of pipes, tubes, and hoses. Factors such as the diameter of the pipe, its length, the number of bends, and the smoothness of the inner wall contribute to this friction. Consequently, a reduction in air pressure occurs due to this resistance. Additionally, pressure drops can also happen at the point of use, particularly if the line is inadequately sized, which can significantly affect the performance of the equipment being powered.
When designing and maintaining a compressed air system, it is essential to take pressure measurements at various locations to detect and resolve potential issues before they escalate. The Compressed Air Challenge recommends specific points for regular pressure assessments to accurately gauge the operating pressure of your system.
Inlet to compressor (to monitor inlet air filter) vs. atmospheric pressure
Differential across air/lubricant separator
Inter-stage on multistage compressors
After-cooler
At treatment equipment (dryers, filters, etc.)
Various points across the distribution system
Check pressure differentials against manufacturers’ specifications. If high pressure drops are noticed, this indicates a need for service.
After taking the necessary measurements, you should sum the recorded pressure drops and subtract this total from your compressor’s operating range. The resulting value represents the actual operating pressure at the point of use.
If your distribution system is correctly sized and the pressure drops across your equipment are within acceptable limits, any pressure drop observed at the point of use suggests a lack of sufficient air volume. This issue may stem from restrictive fittings or inadequately sized air lines, hoses, or tubes. It is essential to ensure that the point of use product is installed in accordance with the manufacturer’s specifications for compressed air.
If you have questions about pressure drops, or anything regarding EXAIR and our products, please do not hesitate to reach out.
Noise levels or sound levels are an important consideration in many industrial settings. Noise exposure can cause irreparable damage if the necessary safety precautions are not taken. OSHA standard 29 CFR – 1910.95 (a) addresses this very concern.
But when discussing sound levels, there are two terms that frequently come up – Sound Power, and Sound Pressure. So, what’s the difference?
Sound Power (measured in watts) refers to the rate at which sound energy (measured in decibels) is emitted, reflected, transmitted, or received over time. On the other hand, sound pressure is the local pressure change from ambient atmospheric pressure caused by a sound wave. From these definitions, we can see that sound power is what creates the sound wave, while sound pressure is the result of what we perceive after the sound wave reaches our ears.
A good way of conceptualizing this is to imagine a light bulb. Light bulbs use electricity to produce light, which means the power needed (also measured in Watts) to make the bulb shine is similar to sound power. The brightness of the light produced (measured in lumens) corresponds to sound pressure. Sound pressure is essentially what we hear or refer to as sound. This is what gets measured because it can be harmful to our hearing. If the sound pressure is too high and the ear is exposed for too long, it can lead to permanent damage, hence OSHA’s regulation mentioned above. This regulation is the result of testing performed to determine what time thresholds at which permanent damage to human hearing will occur due to exposure over a period of time. The higher the sound pressure level, the less exposure time necessary to produce irreparable damage. Within this regulation is included a time weighted chart that OSHA follow for noise exposure issues that serve as the metric by which they determine if a company is in compliance. If not, they may recommend engineering changes, work process changes or require the use of PPE (hearing protection) if the other types of controls cannot be implemented.
If you would like a way to measure noise levels in your facility, EXAIR has the perfect product – EXAIR’s Digital Sound Level Meter. We have a video blog covering its benefits and operation here.
Generally speaking, compressed air-generated noise within a facility can be rather prevalent and loud. So, if you would like to discuss how EXAIR’s quiet and efficient compressed air products can help reduce noise levels in your facility, then give us a call!
EXAIR Six Steps To Optimizing Your Compressed Air System
Since air compressors use a lot of electricity to make compressed air, it is important to use the compressed air as efficiently as possible. EXAIR has six simple steps to optimize your compressed air system. Following these steps will help you to cut electrical costs, reduce overhead, and improve your bottom line.
Step 1 – Measure the air consumption to find sources that use a lot of compressed air. Information is important to diagnose wasteful and problematic areas within your compressed air system. To measure air consumption, flow meters can be used to find the volume or mass of compressed air per unit of time. Flow rates are very useful data points to find problems like leaks, over-use in blow-offs, waste calculations, and comparison analysis.
Step 2 – Find and Fix the Leaks.  One of the largest problems affecting compressed air systems is leaks. That quiet little hissing sound from the pipe lines is costing your company a lot of money. A study was conducted by a university to determine the percentage of air leaks in a typical manufacturing plant. In a poorly maintained system, they found on average that 30% of the compressor capacity is lost through air leaks. For a 100 hp compressor, you are losing 30 hp into the ambient air. To put a dollar value on it, a leak that you cannot physically hear can cost you as much as $130/year. That is just from one inaudible leak in hundreds of feet of compressed air lines. EXAIR offers an Ultrasonic Leak Detector to find those inaudible leaks to fix.
Step 3 – Upgrade your blow-off devices with engineered products. Here is a simple example. A 1/4″ copper tube blow off can consume as much as 33 SCFM (934 SLPM) when supplied with compressed air at 80psig (5.5 bar). It’ll give you a loud, strong blow off. If you replace that copper tube with an engineered nozzle, a Model 1100 Super Air Nozzle, you can reduce that flow to just 14 SCFM (396 SLPM) at 80 PSIG (5.5 bar). If you’re tracking your compressed air usage, you’ll see that replacing just one of them saves you 45,600 Standard Cubic Feet worth of compressed in one 5 day (8 hour a day) work week. At $0.25 per 1,000 cubic feet of compressed air, that’s a savings of $11.40 per week. Also, the noise level will be dropped to 74 dBA to make it comfortable when working nearby.Â
Step 4 – Turn off your compressed air when not in use. This step can be done using two simple methods, either by using manual controls such as ball valves or automated controllers such as solenoid valves. Manual controls are designed for long use and when switching on and off are infrequent. Ball Valves are one of the most commonly used manual shut-offs for compressed air and other fluids. The solenoid valves can be used for quicker shut-offs. With the cost of compressed air, every bit counts. If there are gaps in your operation, they can be triggered with different types of methods. EXAIR does offer an Electronic Flow Control that has an optical eye and timing sequences to trigger solenoid valves to blow compressed air only when it is required.Â
Step 5 – Install Secondary Receiver Tanks.  Compressed air receiver tanks are an integral part of many compressed air distribution systems. Compressed air is stored at a high pressure after drying and filtration. A secondary receiver tank is located on the floor for pneumatic equipment or systems. Think of a receiver tank as a “capacitor”. It stores the energy within a system to be used in periods of peak demand, helping to maintain a stable compressed air pressure in your system. This improves the overall performance of the compressed air system and helps to prevent pressure swings.  Rather than having to pull from the compressor, a secondary receiver tank can be sized to provide the short-term volume of air for a particular application.
Step 6 – Control the Air Pressure. People tend to overuse their compressed air for many blow-off applications. This can create excessive waste, overwork your air compressor, and rob other pneumatic areas. With Pressure Regulators, they give you control to set the operating pressure. By simply turning down the air pressure, less compressed air is used. As an example, a model 1100 Super Air Nozzle uses 14 SCFM (396 SLPM) 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 (269 SLPM). You are now able to add that difference of 4.5 SCFM (127 SLPM) back into the compressed air system. If we use the average rate of $0.25/1000 cubic feet to make compressed air, this would be a savings of $135.00/year with an 8-hour shift. And, if you have many similar blow-off devices, you can see how this can really add up.
It is important to review and monitor your compressed air system. You can cut your energy consumption, improve efficiency, and save yourself money.  The six steps above will help to diagnose the overall “health” of your compressed air system. EXAIR does carry some of these products to help you measure and analyze. You may have questions about the Six Steps to Optimize Your Compressed Air System, and an Application Engineer at EXAIR will be happy to help.Â
