26 



HARDWOOD RECORD 



December 10. 1'J'21 



YARD AND KILN 



cJ Section Intended to Promote Efficiency^ 

 and Economy in Lumber urging ^ 



Upkeep of the Dry Kiln 



By C. J. M. 



- In woodworking the dry kiln is as important a part of the factory 

 equipment as any indispensable shop tool, and in order that it may 

 perform its work properly and with economic expenditure of heat 

 and human labor, and do so within the shortest possible time, it is 

 very necessary that it should receive a reasonable amount of atten- 

 tion, from time to time, at regular intervals, consisting of careful 

 inspection of the building and all parts of its equipment, and the 

 immediate replacement or repair of anything which would in any 

 way interfere with the good performance of the kiln. This applies 

 with especial force to hardwood kilns. 



Close observation of kiln buildings, their e(|uipment and per- 

 formance in a number of establishments, large and small, in various 

 parts of the country, has impressed the writer with the. fact that 

 many dry kilns are strangers to even casual attention for purpose 

 of maintaining same in condition for good drying, repairs, as a 

 rule, being made only when same become inevitable. 



We hear or read about temperature and humidity control, and 

 the importance of good air circulation in the kiln, whenever and 

 wherever the kiln drying of hardwoods is under discussion, and 

 those who have had the most experience in actual drying fully agree 

 on these three ultra necessities of a good dry kiln (the type or 

 make or building construction all being of secondary importance), 

 to wit: 



Uniform heat distribution in all parts of the kiln. 



Constant and uniform humidity conditions of the kiln air, and 



Fairly intensive circulation of the kiln air over all surfaces of 

 the lumber in each pile. 



Now if this means anything it means an air-tight kiln, as air- 

 tight as any building construction can be made and maintained, into 

 which must be fitted doors as large as will admit a kiln car of 

 lumber. 



It also means that the heating system must distribute the heat 

 required, no matter how much or how little, uniformly over the 

 entire kiln, and must do so without interruption; in other words, 

 the steam circulation must continue to be efficient and remain on 

 the job 24 hours each daj'. 



It further means that the desired degree or percentage of relative 

 humidity of the kiln air must be readily obtained and maintained 

 in all parts of the kiln. This would be impossible unless the kiln 

 is air-tight, and in case of the ventilated type the ventilation is 

 under absolute control. 



Maximum interior air circulation in the right direction also is 

 only possible when there is no interference by air leakage into 

 the kiln. 



It is quite feasible to construct dry kilns of the predominant 

 types, the ventilating, condensing, water spray, individual blower, 

 and house the same in frame, brick, tile, or even concrete buildings, 

 and to obtain therein the most satisfactory drying of heavy oak 

 dimensions, as long as these kilns remain in the physical condition 

 to comply with the axiomatic demands above stated, and this 

 means upkeep, more or less of it, some sooner, some later, accord- 

 ing to type and construction, but any and all must be maintained 

 in their initial and intended state of perfection if they shall con- 

 tinue to deliver the work desired from same. 



Kilns in which are dried the heavier oak dimensions, as wagon 

 stocks, requiring- frequent steaming at higher steam temperatures, 



will naturally suffer more than will kilns charged with one inch 

 lumber partially air dried. 



In this matter of up-keep, as in any other work connected with 

 kiln operation, system and regularity of attention will produce the 

 best results. As soon as a kiln has been emptied of its last charge 

 it should be carefully cleaned of all accumulations of bark, splinters 

 and dirt, and then carefulh- inspected by a competent party, who 

 must observe the condition of the floor, the track supports and 

 rails, walls, roof (very important), doors (most important) ,in open 

 and in closed condition, each coil of the heating system when filled 

 with steam under usual pressure, performance of the traps, if any, 

 operation of the condensers, water sprays, or ventilators, as the case 

 may be, and of the air moving equipment in the case of blower 

 kilns. 



Any defects found should be remedied without delay, and the 

 kiln should not be charged until a re-inspection proves that the 

 defects have been properly attended to. 



The writer will in a subsequent article on this same subject recite 

 a few of the most surprising and unexpected things which were 

 disclosed through sj'stematic inspection, and which, if not remedied 

 when found, would have led to much grief and money loss. As an 

 example, there may be mentioned at this time that in an import.ant 

 ))lant, comprising nearly a hundred kilns, drying heavy oak dimen- 

 sions, the writer found just three kilns free from objectionable 

 defects, such as could not have been remedied by systematic inspec- 

 tion and effort at upkeep. 



Questions and Their Answers 



From time to time we receive inquiries from our readers who have 

 problems to solve pertaining to the yard or to tlieir kilns, of which 

 tliose herein printed are a fair sample. In the past we have generally 

 answered direct, by mail, tliose questions with the solution of which 

 we were familiar, and luive referred to some of our expert friends, 

 those which required special information. 



We will henceforth print as manii of such inquiries, and the proper 

 solution of the problem.<i which they represent, as will prove of general 

 interest, and in this we hope to arouse discussions of the wore impor- 

 tant subjects, thereby serving a greater nwmber of our readers. 



We invite the sending of questions to this department. 



Question 1. — Condenser Pipes Corroding 



We are operatinE a number of condensing kilns, ami regardless of our 

 efforts the condenser pipes seem to deteriorate ver.v fast on their outer 

 surface. 



We have repealedly paintetl these pipes with an asphaltum paint, each 

 time carefully scraping off the rust and scale witli old files and steel 

 brushes, but this paint seemingly did not provide much protection and 

 lasted but a short time. 



Some of the steam pi|)es also get rusty, but not nearly as much as do 

 the condenser pipes. 



If you or any of your readers know of a good proteitlng pipe paint 

 which will last a reasonable length of time we shall very much appreciate 

 to receive the information. A.VXIOUS KILN OWNER. 



Answer to Question 1 

 We have made inquiries of several large industries operating many 

 condensing kilns, and find that severe corrosion of the condenser pipes 

 is more or less general. One very large user of condensing kilns in 

 several plants states that asphaltum paint has proven of no benefit In 

 protection of condenser pipes, even when the pipes were thoroughly 

 cleaned and warmed before application. After trying out several of the 

 asphaltum and oil paints offered for the purpose one of their paint shop 

 foremen reasoned that an oxide body paint wonlil probably serve best and 

 he mixed the following : 



