Deflection Pattern
Engineering Data
Engineering Data
158
A618MS, 821, 831, 92 Series, 98VOH,
H and V Series Registers and Grilles,
Air Pattern Obtained with Various
Deflection Settings
0
0
10'
10'
10'
20' 30' 40' 50' 60'
0
0
10'
10'
10'
20' 30' 40' 50'
0
0
10'
10'
10'
20' 30'
0
0
10'
10'
10'
20' 30'
55° 42° 22° 0° 22° 42° 0° 22°22° 0° 22°
STRAIGHT
22°42°42°55°
A DEFLECTION
C DEFLECTION
E DEFLECTION
G DEFLECTION
Recommended NC Criteria
Communication Environment Typical Occupancy
Below Extremely quiet environment; suppressed speech is Broadcasting studios, concert
NC 25 quite audible; suitable for acute pickup of all sounds halls, music rooms.
NC 30 Very quiet office; suitable for large conferences; Residences, theatres, libraries,
telephone use satisfactory. executive offices, directors rooms.
NC 35 Quiet office; satisfactory for conference at a 15 ft. Private offices, schools, hotel
table; normal voice 10-30 ft.; telephone use rooms, courtrooms, churches,
satisfactory. hospital rooms.
NC 40 Satisfactory for conferences at a 6-8 ft. table; normal General office, labs, dining rooms.
voice 6-12 ft.; telephone use satisfactory.
NC 45 Satisfactory for conferences at a 4-5 ft. table; normal Retail stores, cafeterias, lobby
voice 3-6 ft.; raised voice 6-12 ft.; telephone use areas, large drafting & engineering
occasionally difficult. offices, reception areas.
Above Unsatisfactory for conference of more than two or Computer rooms, stenographic
NC 50 three persons, normal voice 1-2 ft.; raised voice 3-6 ft.; pools, print machine rooms,
telephone use slightly difficult. process areas.
Velocity Limitations
for Various Applications
The sound caused by an air outlet in operation is directly proportional to the
velocity of the air passing through it. By selecting outlets of proper sizes, air
velocities can be controlled within safe sound limits.
The following recommended outlet velocities are within the safe sound limits for
most applications.
Recommended
Velometer
Application Velocities
Broadcasting Studios 500 FPM
Residences 500 to 750 FPM
Apartments 500 to 750 FPM
Churches 500 to 750 FPM
Hotel Bedrooms 500 to 750 FPM
Legitimate Theatres 500 to 1000 FPM
Private offices, acoustically treated 500 to 1000 FPM
Motion Picture Theatres 1000 to 1250 FPM
Private Offices, not treated 1000 to 1250 FPM
General Offices 1250 to 1500 FPM
Stores, upper floors 1500 FPM
Stores, main floors 1500 FPM
Industrial Buildings 1500 to 2000 FPM