NTS San Bernardino Unveils New Quiet Technology Test Facility

An outside view of the test facility

In late 2013, NTS San Bernardino began design and construction on a new quiet technology test facility to support MIL-STD-740-2(SH) for Navy submarine applications. The 17.5’ x 12’ sound proof building houses a system which can output a maximum pressure of 5,500 psig and maximum flow of 20,000 SCFM as well as a minimum pressure of 5 psig and minimum flow of 5 SCFM (standard cubic foot per minute).The Quiet Technology Flow Loop is composed of nitrogen supply tanks pressurized up to 5500 psi. The nitrogen is supplied with a 3” supply pipe through the test article using a pressure blow down process. The airborne and structureborne noise levels of the test article are measured at the desired pressures and flow rates using microphones and accelerometers inside the noise chamber. The GN2 flow rate is set by the control valve and venturi downstream of the test article.

The results of a baseline data test with a closed door and no flow. It was analyzed at 1/3 octave using A weighting

Test data is captured in the adjoining control room where sound measuring capabilities include:

• 15 db – 140 dB Low level microphones
• 24 bit resolution Data acquisition
• Sampling rate up to 100 kHz
• Up to 8 channels (expandable)
• DACS capable of automated sequences with redline control

A vent valve quiet element recently passed structureborne noise testing and just yesterday an air reducer assembly passed the airborne noise testing. NTS San Bernardino expects to have the system fully certified by the end of 2014.