[Code of Federal Regulations]
[Title 40, Volume 24]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR204.54]
[Page 92-93]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 204_NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT--Table of
Contents
Subpart B_Portable Air Compressors
Sec. 204.54 Test procedures.
(a) General. This section prescribes the conditions under which
noise emission standard compliance Selective Enforcement Auditing or
Testing by the Administrator must be conducted and the measurement
procedures that must be used to measure the sound level and to calculate
the average sound level of portable air compressors on which the test is
conducted.
(b) Test site description. The location for measuring noise employed
during noise compliance testing must consist of an open site above a
hard reflecting plane. The reflecting plane must consist of a surface of
sealed concrete or sealed asphalt and must extend one (1) meter beyond
each microphone location. No reflecting surface, such as a building,
signboard, hillside, etc., shall be located within 10 meters of a
microphone location.
(c) Measurement equipment. The measurement equipment must be used
during noise standard compliance testing and must consist of the
following or its equivalent:
(1) A sound level meter and microphone system that conform to the
Type I requirements of American National Standard (ANS) S1.4-1971,
``Specification for Sound Level Meters,'' and to the requirements of the
International Electrotechnical Commission (IEC) Publication No. 179,
``Precision Sound Level Meters.''
(2) A windscreen must be employed with the microphone during all
measurements of portable air compressor noise when the wind speed
exceeds 11 km/hr. The windscreen shall not affect the A-weighted sound
levels from the portable air compressor in excess of 0.5 dB.
(3) The entire acoustical instrumentation system including the
microphone and cable shall be calibrated before each test series and
confirmed afterward. A sound level calibrator accurate to within 0.5 dB shall be used. A calibration of the
instrumentation shall be performed at least annually using the
methodology of sufficient precision and accuracy to determine compliance
with ANS S1.4-1971 and IEC 179. This calibration shall consist, at a
minimum, of an overall frequency response calibration and an attenuator
(gain control) calibration plus a measurement of dynamic range and
instrument noise floor.
(4) An anemometer or other device accurate to within 10 percent shall be used to measure wind velocity.
(5) An indicator accurate to within 2 percent
shall be used to measure portable air compressor engine speed.
(6) A gauge accurate to within 5 percent shall
be used to measure portable compressor air pressure.
(7) A metering device accurate to within 10
percent shall be used to measure the portable air compressor compressed
air volumetric flow rate.
(8) A barometer for measuring atmospheric pressure accurate to
within 5 percent.
(9) A thermometer for measuring temperature accurate to within
1 degree.
(d) Portable air compressor operation. The portable air compressor
must be operated at the design full speed with the compressor on load,
delivering its rated flow and output pressure, during noise emission
standard compliance testing. The air discharge shall be provided with a
resistive loading such that no significant pressure drop or throttling
occurs across the compressor discharge valve. The air discharge shall be
piped clear of the test area or fed into an effective silencer. The
sound pressure level due to the air discharge shall be at least 10 dB
below the sound pressure level generated by the portable air compressor.
(e) Test conditions. Noise standard compliance testing must be
carried out under the following conditions:
(1) No rain or other precipitation,
(2) No wind above 19 km/hr,
(3) No observer located within 1 meter, in any direction, of any
microphone location, nor between the test unit and any microphone,
(4) Portable air compressor sound levels, at each microphone
location, 10 dB or greater than the background sound level,
[[Page 93]]
(5) The machine shall have been warmed up and shall be operating in
a stable condition as for continuous service and at its maximum rated
capacity. All cooling air vents in the engine/compressor enclosure,
normally open during operation, shall be fully open during all sound
level measurements. Service doors that should be closed during normal
operation (at any and all ambient temperatures) shall be closed during
all sound level measurements.
(f) Microphone locations. Five microphone locations must be employed
to acquire portable air compressor sound levels to test for noise
standard compliance. A microphone must be located 7 .1 meters from the right, left, front, and back sides
and top of the test unit. The microphone position to the right, left,
front, and back sides of the test unit must be located 1.5 .1 meters above the reflecting plane.
(g) Data required. The following data must be acquired during noise
emission standard compliance testing:
(1) A-weighted sound level at one microphone location prior to
operation of the test unit and at all microphone locations during test
unit operations, as defined in paragraph (d) of this section.
(2) Portable air compressor engine speed.
(3) Portable air compressor compressed gas pressure.
(4) Portable air compressor flow rate.
(5) All other data contained in Appendix I, Table IV.
(h) Calculation of average sound level. The average A-weighted sound
level from measurements at the specified microphone locations must be
calculated by the following method:
L=10 log (1/5[Antilog L1/10+Antilog L2/10+Antilog
L3/10+ Antilog L4/10+ Antilog L5/
10])
Where:
L=The average A-weighted sound level (in decibels)
L1=The A-weighted sound level (in decibels) at microphone
position 1
L2=The A-weighted sound level (in decibels) at microphone
position 2
L3=The A-weighted sound level (in decibels) at microphone
position 3
L4=The A-weighted sound level (in decibels) at microphone
position 4
L5=The A-weighted sound level (in decibels) at microphone
position 5
(i) The Administrator may approve applications from manufacturers of
portable air compressors for the approval of test procedures which
differ from those contained in this part so long as the alternate
procedures have been demonstrated to correlate with the prescribed
procedure. To be acceptable, alternate testing procedures shall be such
that the test results obtained will identify all those test units which
would not comply with the noise emission limit prescribed in Sec.
204.52 when tested in accordance with the procedures contained in Sec.
204.54 (a) through (h). Tests conducted by manufacturers under approved
alternate procedures may be accepted by the Administrator for all
purposes.
(j) Presentation of information. All information required by this
section may be recorded using the format recommended on the Noise Data
Sheet shown in Appendix I, Table IV.
[41 FR 2172, Jan. 14, 1976, as amended at 41 FR 8347, Feb. 26, 1976; 47
FR 57711, Dec. 28, 1982]