Honeywell MS4103 manual Damper Sizing, Approximate industry standard damper lb-in. per sq ft value

AC&DD

Damper And Actuator Sizing

Table 2. Approximate industry standard damper lb-in. per sq ft value.

			Face Velocity (fpm)/
			Static Pressure (in. wc
Leakage	Damper	500/	1000/	1500/	2000/	2500/
	Blades	1	2	3	4	5
Low	Parallel	4	7	10.5	12	14
Low	Opposed	3	5	7.5	8.5	10
Standard	Parallel	3	4.5	6.5	7	8
Standard	Opposed	2	3	4.5	5	6

Damper Sizing

Dampers can be sized using two different methods; actual sizing and nominal sizing. When actual sizing is used the damper dimensions will be the same as the sizes ordered. For example, when a 24 inch x 24 inch D640 damper is ordered, it will be made such that the height is 24 inches and the width is 24 inches. When nominal sizing is used, the damper dimensions will be ¼ inch smaller than the sizes ordered. For example, when a 24 inch x 24 inch D640 is ordered, it will be made such that the height is 23.75 inches and the width is 23.75 inches. No special allowances are required for dampers that are constructed of multiple sections. For example, a damper that is 24 inch x 60 inch will be constructed of two sections. When ordered using nominal sizing, the damper size will be 23.75 inches high by 59.75 inches wide.

Actual sizing is commonly used when the exact size of the opening is known or if the damper is not meant to be installed inside an opening or duct. Nominal sizing, with its ¼ inch undersizing is commonly used when the damper will be installed inside an opening or duct and space is needed for positioning or seal material.

Honeywell’s sizing default is nominal sizing. If actual sizing is required, please make sure this is specified on the order. For more information on ordering Honeywell dampers, please contact your local Honeywell distributor or sales representative.

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