KILN DRYING HANDBOOK 83 
DETAILS OF KILN OPERATION 
The successful operation of dry kilns requires constant and careful 
attention. ‘The results secured depend to a large degree upon the 
operator, and he should be impressed with his obligation to make 
every effort to turn out perfect stock. The first duty of a new 
operator is to familiarize himself with the kilns under his super- 
vision. Before making the initial run in a kiln, he should inspect 
it thoroughly to assure himself that the structural work, including 
the rails, is mechanically safe, that the heating coils, traps, and simi- 
jar parts are in proper working order, and that the instruments 
have been calibrated and, after being properly placed in the kiln, 
have been checked by additional brief comparison with a standard 
instrument. Efficient care of instruments requires the recording in 
a log book of all full calibration readings, together with check read- 
ings, and brief memorandums of all work done on the instruments. 
PERIODIC INSPECTION OF KILN 
The kiln building should be kept structurally sound; each part, 
of course, must be sufficiently strong and rigid for its duty, but in 
addition the building should be tight, as tight as a good residence. 
Maintaining the doors in good repair will retain the large amount of 
heat allowed to escape by poorly fitting ones, usually with a resulting 
- upset of the drying conditions. It is extremely difficult to maintain 
high humidities in a leaky kiln. Rails and rail supports, together 
with their fastenings, should be inspected periodically. Proper 
repair of the pipes is highly important. Besides the usuai looking 
after leaks and other ordinary matters obviously necessary, their 
pitch to the drain end should be maintained both to allow free flow of 
the condensate to the traps and drainage of air from the system. The 
coils should be inspected occasionally to make sure that all of them 
are working, and the traps should be examined every day. Suitable 
runways should be provided to enable men entering the kiln to do 
so with safety and without walking on the pipes. These runways, 
preferably gratings, must be so arranged that they will not interfere 
with the air circulation; in general, solid planking should not be used 
for this purpose. The interior surfaces of the building and also the 
iron work and the pipes should be protected with a good kiln paint; 
the pipes, however, can be painted with a mixture of cylinder oil and 
graphite if this type of protective coating is preferred for them. ‘The 
latter coating can best be apphed when the pipes are hot. 
CALIBRATION AND ADJUSTMENT OF INSTRUMENTS 
Success in all except the simplest kind of kiln drying and the most 
easily dried stock depends upon the accuracy of the instruments and 
of the apparatus used in the regulation of the kiln and in the deter- 
mination of the moisture content, as well as upon the condition of the 
kiln, upon the schedule, and upon the operator. It is therefore essen- 
tial that all of the control equipment be maintained precisely in its 
correct operating condition. Most important is the calibration and 
adjustment of temperature indicating, recording, and regulating in- 
struments, since through them both temperature and humidity are 
determined and also controlled. 
