6 BULLETIN 894, U. S. DEPAKTMENT OF AGRICULTURE. 
The pump room should be centrally located in regard to kilns and 
boiler room, or steam supply. 
Access to fresh water and suitable drainage for waste water have 
a bearing on the location and established grade of the kiln rails. 
KILN CAPACITY. 
To estimate the capacity in board feet of a kiln of any given size, 
multiply the following factors: 
Thickness of stock in inches. 
Number of rows in height. 
Width of pile in feet (minus allowance for openings between boards). 
Average length of lumber in feet. 
Number of trucks or piles in kiln. 
Or the following: 
Height of pile in inches, less aggregate thickness of stickers in inches. 
Width of pile in feet (minus allowance for openings between boards). 
Average length in feet. 
Number of trucks or piles in kiln. 
In determining the kiln capacity required to maintain a given 
periodic output, a great deal depends on the drying period. Con- 
sideration, therefore, must be given to the following items: 
Kind of stock to be dried. 
Thickness of stock. 
Moisture content of stock at time of loading. 
Moisture content to which stock is to be dried. 
Use to which dried stock is to be put — whether a rapid or slow drying schedule 
is to be preferred from the standpoint of mechanical properties of the wood. 
Where large quantities of lumber of one thickness and species are 
to be dried, long kilns of large capacity are an economy; where a 
variety of sizes or species in smaller quantities are to be dried a 
number of smaller kilns is advisable. 
The number of kilns of a given size necessary to maintain a given 
daily output is determined by the following formula: 
Estimated capacity of 1 kiln 
Desired daily output from MW ^^™'^^ 1 of "clays h == " umte of kflnB - 
drying period 
DRYING PERIOD. 
Table 1 is intended to give an idea of the approximate time 
required to dry plain-sawed 1-inch green and partially air-dry 
stock to 6 per cent moisture content, according to mild drying 
schedules, which will produce material of the highest quality and 
equal in strength properties to air-seasoned stock. For stock over 
1 inch thick and not over 3 inches thick, the time is proportional to 
the thickness; for example, 3-inch stock takes about three times as 
