Many people are familiar with the annoyances of noisy compressors from outdoor chiller equipment and other HVAC equipment. Compressor sound blankets are a great cost-efficient and highly effective way to reduce noise from loud compressors. These blankets were thoughtfully engineered and carefully manufactured to bring the noise from your chiller equipment to an acceptable level.
If you are in the market for compressor sound blankets, there are a few things to note before buying. You should understand exactly what they are, how they work, costs to consider and how to install them before pulling the trigger on your purchase. We will cover the basics on compressor blankets in this post to help you decide what product is best for you to reduce noise from your outdoor chiller equipment.
What are Compressor Sound Blankets?
All compressors and HVAC units are designed and manufactured to reduce as much noise as possible. Unfortunately, they still emit noise, usually a loud steady hum. Compressor sound blankets are cleverly designed to drastically reduce the noise still being emitted. These noise suppression blankets wrap the compressors with acoustic jacketing to contain the noise. The acoustic blankets can also be manufactured to cover the piping and oil separator for added sound reduction.
How do Compressor Sound Blankets Work?
Compressor blankets are typically constructed with multiple layers. The outer layers are usually made out of a vinyl woven fabric from an acoustically transparent material. The acoustically transparent material means that the fabric allows sound waves to pass through the outer layer of the fabric and into the denser absorbing inner layers. The absorbing inner fabric is key to the effectiveness of compressor sound blankets. This allows the sound to be absorbed and deafened instead of reflected back into the atmosphere, simply redirecting the noise.
What to Look For
There are a few characteristics to consider when deciding on compressor sound blankets. These include the NRC rating (Noise Reduction Coefficient) and the STC rating (Sound Transmission Class).
1. Noise Reduction Coefficient
The first rating to watch out for is the NRC rating. This rating measures the absorption of sound. Generally speaking, the higher the rating the better the product is at reducing noise. The two main factors that contribute to the NRC rating are the thickness and density of the blanket.
The NRC rating ranges from 0.0-1.0. For example, if a compressor sound blanket has an NRC rating of .65 this means 65% of the sound in the space is absorbed and the other 35% is reflected back into space. While reviewing sound blankets, keep in mind the higher the NRC rating and the thicker the product the better.
2. Sound Transmission Class
In addition to reviewing the NRC of compressor sound blankets, you should pay attention to the STC (Sound Transmission Class) rating. The STC rating also measures how much the product is able to reduce noise; but instead of measuring the amount of absorption, it measures the transmission loss (or how much sound will still come through the barrier).
STC ratings are found based on sound frequency measurements in Hertz (or Hz). To give a frame of reference, most humans are born with the ability to hear frequencies as low as 20 Hz and as high as 20,000 Hz. However, for standard sound testing purposes, the soundproofing industry measures barrier performance based on a range of 125 Hz to 4,000 Hz.
It is important to consider the NRC rating and the STC rating together, and not solely rely on the STC rating individually. It can be misleading in certain soundproofing scenarios, this is because lower frequencies, below 125 Hz, are not applicable to the STC rating since the scale starts at 125 Hz. Depending on the pitch of the hum coming from your compressor, the STC rating could not be applicable at all. However, if your compressor is emitting higher frequency tones, the STC rating is very important.
How to Install Compressor Sound Blankets
Installing compressor sound blankets is quite simple, especially if you have them made for a custom fit. The blankets wrap around the entirety of the compressor, all the way to the base of the body. You should line up the slots of the blanket with the suction line of the compressor and then use the Velcro strips to secure the blanket 2 inches to the right of the suction line. Velcro is used because it is strong enough to stay fastened even with heavy vibration.
Next, cover the terminal box, it is the square box mounted on the side of the compressor. Wrapping it will not interfere with its function and only aid in the reduction of noise from the unit. All of the Velcro seams should align on top of each other for a snug and secure fit. Repeat the wrapping procedure for any other compressors in your chiller system.
Where to Buy Compressor Sound Blankets
Here at eNoise Control, we provide a selection of high-quality compressor sound blankets. Our compressor sound blankets are custom made to fit your specific model. We provide a design site visit to ensure your new compressor sound blankets will have a custom fit. Our compressor blankets are offered in multiple levels to fit your budget. You can wrap just the compressor or purchase an enhanced noise control package to include the piping and other equipment.