MIL-HDBK-1027/4A
c) Slide and Overhead Projectors. Provide stowage space for
portable carts. See concerns for aspect ratios below.
d) Projection Screens. Base selection of permanently mounted or
stand alone screens on user preference. Permanently mounted screens can
limit chalkboard area. Base justification of electrified projection screens
on local requirements; however, maintenance and repair costs must be
considered. Successful visual presentations depend on arrangements of the
chalkboard and projection screen relative to the seating configuration.
(1) Avoid visual obstructions. Provide clearspan structural
systems where possible. Large demonstration tables when raised on platforms
can obscure the lower areas of chalkboards.
(2) Slope the floor and raise the speaker's platform only
where space is dedicated to projection and large capacity lecture functions.
(3)
Consider the viewing distances.
(4) Conform to the vertical and horizontal viewing angles.
Place seats at a distance from a screen not less than twice nor more than six
times the width of the screen image to be viewed. The angle of elevation
from the eye to the top edge of the screen or chalkboard should not exceed 30
degrees. Where room or seating depth is known, the screen width can be
determined by W=D/6 (preferred) or W=D/10 (minimum), where W=screen width and
D=depth of room or seating. Select particular projection equipment based on
aspect ratios compatible with height and width ratios for the screen. Refer
to Time-Saver Standards for Building Types, 2nd edition, McGraw-Hill Book
Company, for graphic data on projection angles and screen widths. Consult
Architectural Graphic Standards, John Wiley and Sons, for viewing zone limits
and projection medium aspect ratios.
e) Chalkboard and Marker Boards. Porcelain surface marker boards
are generally preferred since they are cleaner and can double as projection
screens; however, scrutinize their use in high security areas due to the
potential retention of images after erasure. Avoid chalkboards in computer
rooms since airborne chalk dust can damage computer hardware.
4.4
Environmental Requirements. For applicable discharge criteria,
consult with the NAVFAC Criteria Office and the cognizant EFD. Refer to
MIL-HDBK-1005/8. Design facilities to meet environmental requirements at
federal, state and local levels. Obtain a MSDS on every toxic or suspected
toxic product to be used at the facility and design in protective measures
and ventilation methods. Comply with all applicable pollution abatement
criteria.
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