Quantcast Sound Reflection Reduction

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MIL-HDBK-1027/3B
2.1.8.6
Filtration to Remove Airborne Lead. Filtration of exhaust air to
the outside will be designed in accordance with current OSHA and local
regulatory requirements.  Recirculation of range air is permitted only if it
is properly filtered for airborne range contaminants and includes dirty filter
indication.  If required by Government or local regulations, High Efficiency
Particulate Air (HEPA) Filter shall be provided. Provisions should be made in
the design for increasing fan horsepower and static pressure in the future for
HEPA installation if not an initial design requirement.
2.1.8.7 Other Techniques/Controlling Airborne Lead. There are techniques
for controlling airborne lead such as building a wall in front of the firing
line and shooting through 18 in. diameter (457 mm) ports, thus separating the
muzzle from the face of the shooter.  Another technique is shooting through a
cylinder which has an exhaust connection to remove airborne lead as it leaves
the muzzle.  Electronic lead dust collection plates will be considered for
heavily used ranges where the savings generated by less frequent changes of
the expensive HEPA filters will offset the cost and the equipment costs.
Unique and unusual installations are outside the scope of this manual.
Approval from the using activity must be obtained before using these
techniques.  Criteria may be obtained from the National Rifle Association or
other expert authority.
2.1.8.8 Lead Dust in Existing Ranges.  The use of special training
ammunition may be considered to reduce the cost of rehabilitation of an
existing ventilation system; only if commend assurance is provided that all
users of the range will use this type ammunition. An existing indoor range
with a lead dust level in excess of norms1 exposure limits may be operated
following the restricted criteria found in Table 3. Table 3 is developed and
used by the US Army and the National Guard.  Any constraints on range use must
be in writing end included in the Standard Operating Procedure for the range.
2.1.9
Sound Reflection Reduction. Noise reduction in the range and noise
transmission out of the range are two different design considerations.  Mass
and limpness are the two desirable attributes for a sound transmission
barrier.  Heavy masonry walls are generally the most economical method for
isolating the range.  Other types of construction such as gravel or grout.
filled concrete block will provide mass.  Absorptive acoustical surfacing will
reduce the noise level in the range but will have little effect on
transmission outside the range.  Blown-on acoustical material is not
permitted.  Conventional acoustical treatment is encouraged behind the firing
line.  Downrange acoustic treatment must be compatible with the planned lead
dust removal process.  Do not paint downrange block walls or acoustic tile
sound absorbing walls; this significantly degrades the sound absorbing
qualities of the materials.  Existing ranges may continue use of painted
surface.
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