Description
When the first ASR-9 site was being set up at LAX in 1990, the noise level were found to be totally objectionable—upwards of 82dBA in the equipment room, FAA NCP Baffles were in order. ASC was contracted by FAA site technicians and we provided temporary noise barriers. After extensive engineering analysis, working closely with FAA engineers, we developed our first air-breathing baffle system, the NCP-10. This was in response to the FAA request for the “the finest system you can provide.”
NCP-10 – Designed for the ASR-9 Sites, and the NCP-8 – Designed for the Mode-S sites
Custom designed & manufactured for the FAA
When the first ASR-9 site was being set up at LAX in 1990, the noise level were found to be totally objectionable—upwards of 82dBA in the equipment room. ASC was contracted by FAA site technicians and we provided temporary noise barriers. After extensive engineering analysis, working closely with FAA engineers, we developed our first air-breathing baffle system, the NCP-10. This was in response to the FAA request for the “the finest system you can provide.”
We have provided 75% of all ASR-9 sites with our top-quality NCP-10 system (Noise Control Package). Mode-S was the next upgrade by FAA for ASR-9 sites and accordingly, we developed the NCP-8 system to the same exacting standards of performance, acoustics, handling, and durability established by the NCP-10 system.
See our in-depth descriptions of the NCP-10 baffle system for ASR-9 sites, the NCP-8 for Mode S sites and our ARTCC baffle System. Your personnel will appreciate the significant noise reduction.
The NCP -10 has been developed for the Northrup Grumman ASR-9 radar system. The Beta test sight was LAX, where two systems remain installed and operational. The NCP-10 meets all expectations in terms of free airflow, sound attenuation, compatible appearance and ease of handling. Since then 75% of all ASR-9 equipped airports have the NCP-10 Noise Baffles.
Each baffle is engineered to fit within the physical constraints for clearance and safety yet provide the appropriate sound attenuation for the opening engaged while maintaining a 100% open-air passage through the trap. No single acoustic baffle pattern is used, each sound trap is designed for its specific application. All traps that fit similar openings are identical and interchangeable. There are four types of traps, each so different from the other that there can be no confusion as to which goes where.
The NCP – 10 is a 10 piece noise control package. Each unit is designed and built to engage one or more of the ventilation openings of the ASR-9 Transmitter/Receiver Sets.
Custom noise control packages available for:
- ASR-9 Sites
- Mode-S Sites
- ARTCC Sites
The NCP-8 and the NCP-10 packages are available direct through ASC
Each package is custom manufactured to FAA Approved Specifications
NCP-8 retrofit noise control package for Mode-S radar sites
The NCP-8 is a noise control device engineered for use with the Mode-S. It is designed to be an integral part of the Mode-S system in both function and appearance. NCP-8 is composed of 4 inlet and exhaust noise baffles.
Intake Noise Baffles:
- High Efficiency
- Easy to Handle
- Roller Wheels
- 100% Open Airflow
- Color-Matched
- 12″ x 37″ x 43″
- Weight: approx. 64 lbs
Exhaust Noise Baffles:
- Lightweight
- Easy to Handle
- High Efficiency
- 100% Open Airflow
- 13″ x 27″ x 6′
- Weight: approx. 16 lbs
Physical Description:
Inlet:
The inlet baffle of the Mode-S is a roll-around absorptive barrier. It has handles and ball wheels for easy positioning and removal. This baffle incorporates the acoustic plenum method for noise control. The 100% free air flow entry into the baffle occurs at the floor line as well as at the top opening. The sides of the baffle are sealed to the face of either type of Mode-S doors.
Exhaust:
The exhaust baffle for the Mode-S is a small cabinet top that incorporates the absorptive acoustic barrier method for noise control. The leg supports leave all sides open, allowing absolutely unrestricted airflow. It is lightweight, easily handled and can be used with either style of Mode-S exhaust openings.
Sound Baffle for the Mede-S specifications and safety data
ASC was commissioned by the FAA to develop a noise suppression system for the ASR-9 and the Mode-S. Great care was taken to accommodate the stringent demands from the FAA for safety, durability, design and ease of installation. ASC not only met those criteria but surpassed them with the development of the NCP-10 for the ASR-9 and the NCP-8 for the Mode S.
The NCP-8 is 100% welded construction of 18 gauge galvanized and etched sheet metal. The floor-standing units are supported by four ball bearing casters, with a load capacity of 75 lbs each, and have handles attached at either end for easy handling..
The NCP-8 is electrostatic powder coat painted. This is a highly scratch-resistant surface that is color-matched to the Westinghouse-built Mode-S, as is our NCP-10 to the ASR-9. The weights are: 64 pounds for the roll-around air inlet unit and 16 pounds for the exhaust noise baffle..
The sound-absorbing material used in the NCP-8 is a 2″ fiberglass panel extensively used in the HVAC industry. The fiber shedding of this panel is well below the permissible exposure limit (REL) proposed in 1977 by the National Institute of Occupational, Safety and Health (NIOSH) of 3.0 fibers/cc. All cut edges of the sound-absorbing material are coated with a fiber retaining sealant. In addition the surface and edges are covered with a spunbond polypropylene dust cover. The dust cover is then covered with a 40% open-weave monofilament plastic screen. This final surface handles wind and any other mechanically abrasive contact.
The NCP-8 is designed to meet the same handling and stacking requirements as the NCP-10 system. They nest efficiently, requiring minimal floor space for storage. All noise baffles are able to be easily and quickly removed from the signal processing cabinets. When rolling, the cabinets are well balanced and stable. The baffle equipment is designed to interface with the Mode-S without risk of damage to other FAA equipment. Another FAA requirement is interchangeability. Our noise baffle is engineered to fit either of the Mode-S doors. The exhaust units are also interchangeable.
The lifetime of the NCP-8 unit is expected to be indefinite when used indoors and for its intended purpose.
NCP-8 Acoustic performance: Mode-S report
The noise level for a commissioned Mode-S has been measured to be 86 dB,A at the face of the air inlet grill. The NCP-8 inlet baffle was tested in the lab and the results compared to the field measurements of the Mode-S inlet noise. The results were as follows: (All measurements are in dB,A).
An air inlet noise baffle was designed and built to fit the Mode-S cabinet and to meet FAA handling requirements. This roll-around noise baffle is a plenum baffle. It measures in the laboratory mock-up testing to produce 16 dB,A attenuation as measured at the upper inlet opening of the baffle. This is well within the performance expected from this plenum baffle design.
The sound source used in these tests was flat within 3 dB,A when filtered through the weighting filters. This is very close to the actual sound source spectrum. The lab noise source that measured 84 dB,A at the opening was reduced to 68 dB,A at the opening of the baffle. The baffle produces 16 dB,A attenuation. With the lab tests we have demonstrated that our sound baffle meets the needs of the site.
| TRANSMITTER INLET | ||
| Field Noise Source |
Lab Noise Source |
|
| No Baffle | 86 | 84 |
| With Baffle | 70 | 68 |
| Attenuation | 16 | 16 |
| Less | -2 | |
| Required Level |
72 | |
| Required Attenuation |
14 | |
Noise levels at the inlet of the Mode-S read 86 dB,A. Our NCP-8 baffle will knock down 16 dB,A and the resulting noise level at the air inlet opening of the baffle will be 70 dB,A. Noise output from the baffle will always measure less than this 70 dB,A regardless of where the measurement is taken.
Acoustic Testing
With these tests we have demonstrated that our sound baffle design meets the needs of the site. Sound at the opening will be 72 dB,A and will measure substantially less than the 78 dB,A at the 5 foot distance requirement.
Industrial Baffles: NCP-10 Noise Baffle
NCP-10 Retrofit Noise Control Package for the ASR-9 Radar Site
The noise control package, NCP -10, has been developed for the Northrup Grumman ASR-9 radar system. The Beta test sight was LAX, where two systems remain installed and operational. The NCP-10 meets all expectations in terms of free airflow, sound attenuation, compatible appearance and ease of handling. Since then 75% of all ASR-9 equipped airports have the NCP-10 Noise Baffles.
Each baffle is engineered to fit within the physical constraints for clearance and safety yet provide the appropriate sound attenuation for the opening engaged while maintaining a 100% open-air passage through the trap. No single acoustic baffle pattern is used, each sound trap is designed for its specific application. All traps that fit similar openings are identical and interchangeable. There are four types of traps, each so different from the other that there can be no confusion as to which goes where.
The NCP – 10 is a 10 piece noise control package. Each unit is designed and built to engage one or more of the ventilation openings of the ASR-9 Transmitter/Receiver Sets.
The NCP-10 package consists of 10 units:
- NCP-10-A 2 Transmitter air inlet roll around cabinets
- NCP-10-B 2 Receiver air inlet roll around cabinets
- NCP-10-C 2 Transmitter air exhaust baffle boxes
- NCP-10-D 4 Receiver air exhaust baffle boxes
There are 4 large roll around baffles that weigh about 190 lbs each and handle the noisiest inlet air. On top of the Northrup Grumman radar cabinets there are 6 smaller units to quiet the less noisy airports. All units have a continuous 100% open area and are intended to be easily and quickly removed or replaced. They are beige in color, similar to the color of the Northrup Grumman radar cabinet.
The roll-around cabinets can only fit up to the air inlets one way but the baffle boxes that are set on top of the cabinets can be installed forwards or backwards without impact, as they are symmetrical. A design goal was to facilitate accurate damage-free, fit or no-fit positioning of the sound traps by any personnel who may be unfamiliar with them.
The target sound level reduction with all sound traps in position was to achieve 70-71 dB,A in the open area of the transmitter site. This is a full 10 dB,A reduction from the untreated 82 dB,A sound levels. The current improved version of NCP-10 achieves and surpasses this goal by incorporating Acoustic Sciences Corporation’s patented bass traps in the inlet baffles. This enables the absorption of lower frequencies thus increasing the efficiency of the Noise Baffle.
Intake Noise Baffles:
- High Efficiency – Achieved by a 2 Stage Acoustic System
- Easy to Position – Roll Around Cabinets With Handles For Easy Maintenance
- 100% Open From The Inlet Of The Baffle To The Inlet Of The ASR-9 Resulting In A No Head Loss Flow Constriction
- Easy Inspection Of Air Filters Through Side Viewing Holes
- Compatible Fit – Looks Like Original Equipment Sized For Aisle Clearance
- Incorporation Of ASC’s Patented Bass Traps For Low-Frequency Absorption
Intake Noise Baffles:
- Matched Muffler – Sized and Baffled To Achieve Necessary Attenuation
- Easy Setup – These Lightweight Units Are Interchangeable and Reversible
- Free Draft – 100% Inlet Area Is Maintained While Line of Sight Is Blocked
- Safety Design – Adequate Clearance For All Critical Components
- Custom Designed Compatibility With ASR-9 Radar Sites
Physical Description:
Each Sound Baffle was designed for its location, clearance fit and required attenuation. The inlet cabinets are similar in design but the exhaust baffles are different in shape, size and internal structure. All baffles do maintain 100% open area, 0% line of sight and no more than 90E turns in the airflow.
NCP-10-A the Transmitter Baffle is a roll-around unit that has one air inlet and one air outlet. It uses a two-stage acoustic system. Low-frequency noise is damped out by our patented bass traps, used here for maximum volumetric efficiency. Two portholes are installed, one for a flashlight, the other for the line of sight to easily inspect the air filters. The air rush noise is attenuated by the section of parallel-lined ducts.
Size: 13″ x 40″ x 60″ Weight: 215 lbs
2-Stage Design
NCP-10-B the receiving Inlet Baffle is a roll-around unit that has one air inlet on top and two outlets low to the floor. It is built like the NCP-10-A except that it has been reconfigured for two outlets. It is a smaller unit because less attenuation is needed and has air filter inspection parts.
Size: 13″ x 40″ x 48″ Weight: 170 lbs
2-Stage Design
NCP-10-C the Transmitter Exhaust Baffle is shaped to accommodate the microwave beam tube that it sits alongside of. The acoustic system uses a staggered baffle to provide appropriate attenuation in the allowed space and geometry. It rests on felt skids.
Size: 14″ x 20″ x 42″ Weight: 45 lbs
Three Step Stagger Baffle Design
NCP-10-D The Receiver Exhaust Baffle is the smallest and most simple sound trap. The sound baffle design consists of a single stage staggered baffle, adequate for the amount of noise emitted from the exhaust part it is paired to. It rests on felt skids.
Size: 14″ x 10″ x 6″ Weight: 6 lbs
One Step Stagger Baffle Design
NCP-10 Acoustical Design:
Although each unit of the NCP-10 package is designed for the noise source to which it is mated, there are some similarities. The primary sound-absorbing element used throughout this system is 2″ thick acoustical fiberglass covered by a fine mesh geotextile screen. This combination creates a sound trap that is highly absorptive and mechanically durable. The original production models built between 1991-95 incorporated a metal mesh-lined wavy duct pattern instead of the present straight duct.
Lined Duct – This technique is used for high sound attenuation of air rush noise, and 100% open airflow. The absorptive strips are 2″ thick and separated by 2″ of air space. It allows for minimal air pressure drop or head loss. This produces 3 dB/foot for all sound above 500 Hz.
Bass Traps – ASC’s patented bass traps are located inside branch cavities to pull out the otherwise difficult to attenuate low-frequency noise. Here, semi-cylindrical units are made out of sound absorptive fiberglass that enclose an air cavity. It is the size of the cavity that determines the low-frequency efficiency. The traps used here still have high absorption for sound 55 Hz and above.
Blocked Duct – Air rush noise is also controlled by a sequence of staggered baffles that block the sound but allow air to flow. Here the sound simply meets head-on with a series of sound-absorbing walls. The air, however, flows around the objects. The line of sight is 100% blocked. Flow of air remains 100% open and the attenuation is about 2dB per stage.
