18 BULLETIN 1335, U. S. DEPARTMENT OF AGRICULTURE 
All forced-draft driers, therefore, should be provided with recircula- 
tion ducts connecting the air-outlet end of the drying chamber with 
the heaters and with dampers controlling the air discharged, recircu- _ 
lated, and drawn from the outside. 
eaee PUSHES PAU ee 
BRSlba bh 
Sever belgesel 
st AS 
fate RSA Va 
PC 
faa SSRs 
ane ae a 
Sas leat alors aes 
ic SSIS acl 
Sa ieie 5 SASS 
He 
a 
Ba 
ei 
fe 
= 
fal 
ig 
Pome 
mh cow (Gn Sa SE Yl PS Sy 
fe is es td Sy cas 
af a off til ated 
ee 
See ecaledelive ie. 
K e 
zo & oleh ea 2 
062 eae Sy Sees ¥ 
S PASS SSS eZ S 
064 fe N SS iy, < 
yy nm i 
x Q 
Q zx by 
066 22 joo & = a W 
POUNDS OF DRY A/R PER CUBIC FOOT” 
POUNDS OF WATER VAPOR PER CUBIC FOOT. 
076 
+ SONG sisi 
| = SS 
, ede, 
= wisi 
A ae ee ae ee 
i | See Datos is oh 
. Z, 60 680 100 
i pe A a beet PER CENT RELATIVE HUMIDITY PER CENT 
4 DRY AlP WATER VAPOR 
; 
i Fic. 8.—Pounds of dry air and of water vapor per cubic foot, at a barometer reading of 29.921 (based on 
: Table 1, page 430, volume i, Mechanical Equipment of Buildings, by L. A. Harding and A. C. Wil- 
ia lard, 1917) 
ie DETERMINATION OF AIR CONDITIONS 
i) | Figures 7, 8, and 9 will assist in solving recirculation problems. 
The curves in Figure 9 are vapor-pressure curves, graduated and 
expressed as pounds of water vapor per pound of dry air instead of 
ee 
