FOREST SERVICE WATER SPRAY DRY KILN. 37 
valve capable of maintaining any water pressure desired between 40 
and 60 pounds. In case the pressure* in the cold-water main is less 
than 50 pounds an extra cold-water pump and well are required. 
INSTALLATION OF WATER PIPING AND FITTINGS. 
All piping should be genuine wrought iron of standard weight. 
Joints should be perfectly tight, iron to iron, without the use of red 
lead or cement. 
Tees with plugged openings for wateF gauges should be installed 
on the kiln side of each water mixer and on the discharge of the pump 
beyond the strainer. (See fig. 11.) 
The cold, recirculating, and hot-water mains should each be con- 
nected and properly valved to by-pass the water mixer separately. 
An accurate water-pipe thermometer should be installed in the 
spray-line supply on the discharge side of the water mixer. 
The spray-line pipe in the spray chamber should be in the middle 
and should be extended through the kiln wall at each end to a sill 
cock, in order that the system may be flushed out 
WATER MIXERS. 
Each kiln should be provided with a thermostatic water mixer, 
installed between unions so that it may be removed for cleaning and 
inspection. 
Some water mixers have a temperature range of only 60 degrees, 
others as high as 100 degrees. The upper limit of the temperature 
range of a mixer should be at least 20 degrees higher than the lowest 
initial temperature of the drying schedule to be used in the kilns. 
Water mixers are entirely self contained, requiring no outside 
agency such as air or electricity to operate them. 
Inlets and discharge should be full size of spray-line supply. 
WELLS. 
RECIRCULATING WELL. 
The well should be capable of holding a supply of water for 10 
minutes and the required capacity may be 'determined as follows: 
Pounds per kiln per minute X number of kilns X 10 
= cubic feet required in well below water line. 
The hot well, where used, should be about one-third the size of 
the recirculating weU. When the hot well is dispensed with, a steam 
pipe should be installed for heating the water in the well when 
required. 
The general shape of a well depends upon local conditions affecting 
the installation, such as nature of soil, drainage system, etc. The 
well should be constructed of concrete, waterproofed with a reliable 
integral waterproofing. 
