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Full text of "The Flow Of Gases In Furnaces"

280

APPENDIX VII


	Gas on
 Gas
	Air on Air
	Gas on
 Waste Gas
	Air on Waste Gas

Valve resistances :
	
	
	
	

QQ= volume flowing  .
	5m3 32
	8m3 51
	5 m3 19
	7 m358

t = average temperature' .....
	500
	50
	750
	550

1 -\-at = gas factor ...............
	2.835
	1 . 1835
	3.7525
	3.0185

Q/ = Q0(l+aO = . .
	15 m3 08
	10 m3 07
	19 m3 48
	22 m3 89

Valve size in inches
	54 in.
	66 in.
	54 in.
	66 in

w= valve area
	1m2 48
	2m2 21
	1 m248
	2 m221

vt  velocity  through  valve =
	
	
	
	

Qj -T- to = m per sec
	10m 19
	4m 56
	13 m  16
	10 m 36

h=vz+2g=.
	5 m 291
	1 m  06
	8 m 83
	5 m 47

A0 = specific weight gases .
	1.125
	1.293
	1.32
	1 32

Ai = A0-5-(l+aO=kg perm3.. .
	0.397
	1.093
	0.352
	0.437

As the gases make a 180 bend in
	
	
	
	

passing through the valve, the
	
	
	
	

velocity   must    be    created
	
	
	
	

twice; therefors, the pressure
	
	
	
	

required will be:
	
	
	
	

5=2/iAz = kgper m2 ...........
	4 kg 201
	2 kg 317
	6 kg 216
	4 kg 781


	
	
	
	

Where changes of direction of flow occur, there is a loss of
pressure, or, more exactly, additional pressure is required to
impress the necessary velocity in the new direction of flow. In
addition, where the gases flow from a larger passage into a smaller,
their velocity of flow increases and additional pressure must be
provided to impress this change in velocity upon the gases. The
pressures necessary for this purpose must be approximated in the
following manner: