EASY TO CHECK IF THE AIR VELOCITY WITHIN LIMIT DESIGN

1. 1. TRANSFER AIR DUCT
2. GRAVITY RELIEF AIR SHIFTS
 MAX FRICTION = 0.03-0.05
in.w.g/100ft
WHEN CFM < 3200
CFM
 MAX VELOCITY = 1000
fpm
WHEN
CFM > 3200
CFM
1. LOW PRESSSURE DUCT
2. GENERAL EXHAUST DUCT
3. TOILETS EXHAUST DUCT
 MAX FRICTION = 0.1-0.15
in.w.g/100ft
WHEN CFM <6000
CFM
 MAX VELOCITY = 1500-1800
fpm
WHEN CFM >6000
CFM
 APPLICABLE FOR SUPPLY,RETURN,EXHAUST AND OUT SIDE AIR
HIGH PRESSSURE DUCT
 MAX FRICTION= 0.4-0.45
in.w.g/100ft
WHEN CFM < 5000
CFM
 MAX VELOCITY = 2500-3500
fpm
WHEN CFM > 5000
CFM
 APPLICABLEFOR SUPPLY SYSTEM ONLY
0033 CFM
0033 CFM
6000 CFM
ACID AMMONIA AND SOLVENTS MAINS
 MAX FRICTION=0.5-0.6
in.w.g/100ft
 MAX VELOCITY =3000
fpm
 MIN VELOCITY =1000
fpm
 MAIN & RISER = 1500-3000 fpm
 BRANCHES & LATERALS = 1000-2000 fpm
MEDIUM PRESSSURE DUCT
 MAX FRICTION = 0.2-0.25
in.w.g/100ft
WHEN CFM < 6000
CFM
 MAX VELOCITY = 2000-2500
fpm
WHEN CFM > 6000
CFM
 APPLICABLEFOR SUPPLY SYSTEM
ONLY
DISH WASHER
EXHAUST DUCT
 MAX FRICTION=0.1-
0.15
in.w.g/100ft
 MAX VELOCITY
=2200
FPM
 MIN VELOCITY 1500
FPM
KITCHEN HOOD EXHAUST DUCT
 MAX VELOCITY =2200
FPM
 MIN VELOCITY 1500
FPM
ACID , AMMONIA AND SOLVENT STACKS
 MAX VELOCITY =4000
CFM
 MIN VELOCITY =3000
CFM
 700FPM ( EXHAUST OR RELIEF )
 MAXIMUM VELOCITY THROUGH FREE AREA
:ASSUMING 50% FREE AREA-MAX.VELOCITY
350 FPM THROUGH GROSS AREA
 500FPM ( INTAKE )
 MAXIMUM VELOCITY THROUGH FREE AREA
:ASSUMING 50% FREE AREA-MAX.VELOCITY
250 FPM THROUGH GROSS AREA
 MIN 250FPM ( SILANE DUCT )
 VELOCITY ACROSS THE NECK OF CYLINDER OR
CABINET WINDOW OR ACCESS PORT
MUSTAFA A. ABDULJABBAR
Mustafahmed94@yahoo.com
Mobile 00971 50 499 50 43
OUTSIDE AIR SHIFT
 MAX FRICTION = 0.05-
0.1
in.w.g/100ft
WHEN CFM <
1200
CFM
 MAX VELOCITY = 1000
fpm
WHEN CFM > 1200
CFM