MODULAR PRE-ENGINEERED DYNAMOMETER TEST CELLS AND COMPONENTS

 

FREQUENTLY ASKED QUESTIONS (FAQ’S)

1. Why do I need a test cell?

 

There are several reasons:

 

  • To control noise in your facility. This will protect your employees from hearing damage and allow you to conduct other business (such as phone calls) while running tests.
  • To prevent your testing from disturbing neighbors and meet community noise standards.
  • To provide the appropriate amount of ventilation during the tests.
  • To have a controlled test environment that allows you to have repeatable results.
  • To provide a safe environment in your facility.

 

 

2. Should I use a modular test cell or build it myself?

 

It depends on your specific needs. Please refer to “The Advantages” section on our web site, then give us a call at 800.472.5952.

 

 

3. Should I care about Noise at my property line?

 

Yes…most municipalities and states have noise ordinances that stipulate how much noise can pass over your property line. You must comply with these laws or face fines and/or operating restrictions. Our modular test cells ensure you meet or exceed any noise ordinance.

 

 

4. I have an existing test cell but it is too noisy…what can I do?

 

Sound will leak through the path of least resistance. If you constructed a test cell of concrete block and did not use a sound rated door or a sound rated window, the sound is probably leaking through these openings.

 

Hard (non-absorptive) walls and ceilings cause reverberation. This can cause noise levels inside and outside your test cell to increase by up to 10dBA. This sounds twice as loud. You will need to add absorptive panels to the walls or ceiling of your test cell. Please refer to the “Components” section on our web site.

 

If you did not use silencers for your intake and exhaust air the noise is escaping out through your ventilation system.

 

Please refer to the “Components” section on our web site… “Sound Control Doors and Windows”, “Absorption Products” and “Silenced Ventilation Systems.”

 

Then give us a call at 800.472.5952.

 

 

5. I have other shop noise…what can I do?

 

If your shop has mostly hard surfaced walls and ceilings (masonry or drywall, metal buildings, etc.) you will need to add absorption to your walls.

 

Refer to the “Components” section on our web site… “Absorption Products”.

 

Then give us a call at 800.472.5952.

 

 

6. Do I need to use mufflers in my test cell?

 

Noise reduction depends upon your specific requirements.

 

Please give us a call at 800.472.5952 and we can help you with a customized solution.

 

 

7. My existing test cell has ventilation problems…what can I do?

 

We can help you redesign your airflow.

 

Refer to the “Components” section on our website… “Silenced Ventilation Systems”.

 

Then give us a call at 800.472.5952.

 

 

8. What is “dBA”?

 

Sound pressure is measured in decibels (dB). The dBA is a weighted measurement that more accurately reflects the way the human ear hears sound. Humans are less sensitive to low frequencies than high frequencies, so the dBA measurement places a higher importance on high frequencies by “weighing” out low frequencies.

 

 

9. What is NRC?

 

NRC, or Noise Reduction Coefficient, is the average sound absorption of the four speech interference frequencies (250 Hertz, 500 Hertz, 1000 Hertz, And 2,000 Hertz). A material with an NRC of 0.95 absorbs approximately 95% of the noise that strikes it. That is, it prevents sound from reflecting off it.

 

 

10. What is STC?

 

STC, or Sound Transmission Class, is a single number rating of a material’s ability to stop sound from going through it. It is used to rate doors, windows, walls, ceilings, or any other partition between spaces. Generally speaking, the higher the STC rating the greater the sound reduction.

 

11. What is noise?

 

Noise is unwanted sound. It does not have to be loud, just unwanted. It can be disturbing, it may interfere with communications or it can be hazardous to your health.

 

12. How loud is my engine or motorcycle?

 

The list below shows typical sound levels measured in dBA:

 

  • Jet Engine 150 dBA
  • Engine Test Cell 130-140 dBA
  • Motorcycle Test Cell 120-130 dBA
  • Human Threshold of Pain 120 dBA
  • Pneumatic Chipper 106 dBA
  • Lawn Mower 98 dBA
  • Heavy Traffic 90 dBA
  • OSHA 8 hour Criteria 90 dBA
  • Typical Manufacturing Plant 80 dBA
  • Normal Speech 70 dBA
  • Typical Office Area 60 dBA

 

 

13. What does a 40 dBA decrease sound like?

 

Every decrease of 10 dBA sounds like the noise is ½ as loud as before. A 40 dBA decrease sounds like the noise has been cut in half four times!

 

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