SINGLE DEFLECTION GRILLES

EX-AL1 Grille with single row of individually adjustable straight vertical blades.
EX-AL2 Grille with single row of individually adjustable straight horizontal blades.
EX-AL6 Grille with single row of fixed 45 degree straight horizontal blades.

Sizing Nomogram for Adjustable Straight Bladed Grilles

In the nomogram "Throw" is the distance the incoming air will travel for its velocity to drop to 50 fpm. The correction factors for various blade angles are used to calculate the Throw from the dimension of the room.

Example Problem:
To size a grille to deliver 900 cfm at a heating differential of 10oF to a room 40ft long x 15ft wide x 12ft high.

Solution:
From the spread characteristics chart on determine the blade angle, in this case 0o. Assume a high level entry, in the centre of the short wall. Find the correction factor (0.75) from the table. Throw = length of room x 0.75 = 30ft. In the nomogram join 900 cfm Air Flow Rate to 30ft Throw and extend to the pivot line. Select a grille of suitable proportions by pivoting about this point, e.g. 20" x 16".Read off Jet Velocity i.e. 550 fpm, check from the Noise Limiting Data that noise rating NR16 (23dB) is acceptable. Check also from the Drop Assessment Chart below that the drop of the airstream is acceptable.

Correction Factors for Throw

Relation between Jet Velocity & Total Pressure

Drop Assessment Chart

The drop of an airstream is due to two causes:

1. Spread - always positive.
2. Temperature Differential between room air and incoming air - positive for cooling, negative for heating.

Example Problem:
To check the suitability of the grille sized on the sizing nomogram.
1.Join the Jet Velocity of 550 fpm to the Throw of 30ft and read off Drop due to Spread = 5.4ft.
2. Join the point of intersection of the above line with the pivot line to the Temperature Differential of 10oF extend back to Drop due to Temperature Differential scale and read off 4.2ft.
3. Total drop of airstream is Drop due to Spread plus Drop due to Temperature Differential i.e. 5.4 + (-4.2) = 1.2ft.
Note: If the problem had been one of cooling then Drop due to Temperature Differential would have been positive i.e. Total Drop = 5.4 + 4.2 = 9.6ft.

Spread Characteristics

For the dimensions of the room, select a blade angle setting to give adequate coverage.

The service of our Technical Department is always available.

Recommended Air Velocities For Various Applications

The services of our Technical Department are always available if required.

Noise Limiting Data

These recommendations are based upon accepted noise ratings for the listed types of environment and upon the sound level of the outlets measured 5ft from the outlet with a room constant of 100.

Noise Chart