22
6. Account of simple rectangle duct
Assume the friction resistance per unitis 1Pa/m, when the size of one side of air pipe is 25omm,
like below figure:
Installation Procedures
The length difference between pipes should be limited
to be less than 2:1;
Make the piping as short as possible;
Keep the min. elbow quantity;
Wind the heat insulating material around the flange
between the main unit and the exhaust pipe for heat
insulation and sealing. Install the piping before fitting
up the ceiling.
incorrect
incorrect
correct
flux
gas pipe
(mmxmm)
1200m
3
/h
(20m
3
/min)
300m
3
/h
(5m
3
/min)
250x310
250x120
B
A
unit
with filter
(purchased additionally)
static pressure box
$
300m
3
/h
%
300m
3
/h
$
1200m
3
/h
$
1200m
3
/h
simple duct selection Note:1Pa/m
flux
item
shape
square pipe
m
3
/h(m
3
/min)
100
200
300
400
500
600(10)
800
1,000
1,200(20)
1,400
1,600
1,800(30)
2000
2400
3,000(50)
3,500
4,000
4,500
5,000
5,500
6,000(100)
250
x
60
size
(mmxmm)
250
x
90
250
x
120
250
x
140
250
x
170
250
x
190
250
x
230
250
x
270
250
x
310
250
x
350
250
x
390
250
x
430
250
x
470
250
x
560
250
x
650
250
x
740
250
x
830
250
x
920
250
x 1000
250
x 1090
250
x 1180
straight pipe
account as 1Pa per meter,
1Pa/m
bended section
each bend regarded as 3-4m
of straight pipe
air outlet section
static pressure box
inlet grille (with filter)
account as 25Pa
50Pa per static pressure box
40Pa for each one
Account of resistance in duct:
