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Table II. Acceptable octave band sound pressure levels in dB re: 20 uPa, or dB re: 0,0002 dyne/cm2 |
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|  MIL-S-24603A(SH)
Acceptable octave band sound pressure levels in dB
TABLE II.
re: 20 uPa, or dB re: 0,0002 dyne/cm2.
Octave band center frequency in Hz
500
lK
2K
4K
8K
250
31.5
63
125
Frequency
76
71
63
58
55
54
54
56
81
Sound pressure level
3.7.5 Vibration. Comminutors and their associated motors, controllers, and
drive mechanisms shall meet the requirements of MIL-STD-167-1, type I, environ-
mental vibration up to and including 50 Hz.
3.8 Service life and operating profile. Design service life of the
comminutor shall be at least 10 years with a 50 percent service factor, or 40,000
hours of normal operation. There shall be no limit to the start-stop cycles
during the life of the comminutor. Parts subject to wear or deterioration shall
have a minimum life of 5,000 actual hours of operation comminuting sewage.
3.9 Reliability. repairability, and maintainability. To the maximum extent
practicable, the comminutor shall require a minimum of preventive and corrective
maintenance. Potential failure modes shall be anticipated and identified and
equipment design shall facilitate the repair actions required under these failure
modes . Parts shall be constructed such that they cannot be reassembled
incorrectly,
3.9.1 Jamming failure. Failure due to jamming shall not cause significant
damage to the comminutor system, The motor controller shall automatically shut
down the comminutor in the event of a jam, before damaging stress levels are
reached. Also, a single, inexpensive, and easily replaceable component (for
example, a shear pin or drive belt) shall fail before damaging stress levels are
reached elsewhere in the system in the event the motor controller fails to shut
off the comminutor. The total time required to restore the comminutor to
operation subsequent to such a failure shall not exceed 2 manhours utilizing on
board repair parts and any special tools provided. The comminutor calculations
and configuration details will be reviewed prior to manufacture.
3.9.2 Seal-mating surfaces. Comminutor construction shall, to the maximum
extent practicable, configure seals and seal-mating surfaces to minimize the risk
of damaging or scoring these components during disassembly, maintenance, and
assembly of the comminutor.
3.9.3 Special tools. Requirements for special tools for disassembly,
maintenance, and assembly of the comminutor shall be minimized. A special tool
is defined as any tool not listed in the Federal Supply Catalog (copies of this
catalog may be consulted in the office of the Defense Contract Administration
Services Management Area (DCASMA)).
3.9.4 Jam corrective maintenance. Comminutor configuration shall
facilitate disassembly and assembly procedures that are necessary to manually
restore operation of a jammed comminutor cutter assembly (see 4.6.8). The
8
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