TABLE SHOWING THE RADIATING SURFACE PER LINEAR FOOT, AND THE LINEAR FEET OF PIPE REQUIRED TO MAKE ONE SQUARE FOOT OF RADIATING SURFACE

Size of pipe in inches Radiating surface per linear foot Linear feet of pipe per square foot of radiating surface

In case steam pipe is used for the radiation, either one and onefourth or one and one-half inch pipe is recommended as the most practical size.

SOME VERY IMPORTANT POINTS TO BE CONSIDERED IN THE SUCCESSFUL HEATING OF A MILL

1. The steam pipes should be located near the floor and so arranged as to give an equal distribution of heat.

2. There should be a water trap to draw off all water accumulating in the pipes.

3. The lower floors and the floors with heavy machinery should have more radiating surface in proportion to the cubic feet of space to be heated than the upper floors and the floors with the light machinery.

4. The steam should be turned on with 25-50 pounds pressure, so as to heat the mill more rapidly.

5. In order to take advantage of the heat in the machinery, the heat should be turned on immediately after shutting down the mill. 6. Stairways and elevator shafts should be closed, so as to make each floor entirely separate.

7. Two or three thermometers should be distributed on each floor in order to know what temperatures you have.

8. Time must be taken to reach the desired temperature.

9. A temperature of from 118° to 125° is sufficient for any part of the mill.

10. This temperature should be held several hours to allow the heat to penetrate all the infested parts.

11. Do not attempt to heat a mill on a windy, a cold, or a rainy day.

THE EFFECT OF HEAT FUMIGATION UPON FLOUR

In connection with heat fumigation, the question naturally arises as to whether the heat would have any deleterious effect upon the baking quality of the flour. To give data upon this subject baking tests were made of a patent hard-wheat flour, a low grade hard-wheat

flour, and a pancake flour. These flours were subjected to a hea several degrees higher than that recommended for a mill. The lov grade hard-wheat flour was not only subjected to a temperature of 140° for nine hours, but the same samples were reheated to the same temperature two and six weeks later to ascertain whether a second and third heating of the same flour would have any injurious effect. The pancake flour was subjected to a temperature of 130° for forty-eight hours. The baking tests of all these experiments showed conclusively that the heat had absolutely no deleterious effect upon the baking qualities of the flours.

SOME UNCALLED FOR CRITICISMS

The objection made by some that the insurance companies will not permit heat is without any foundation. The only instances of an objection of this sort that has been brought to the attention of the writer was in case of mills that may be equipped with the automatic sprinkling system. Mr. William Reed, secretary of the Mutual Fire Prevention Bureau, representing eight of the principal millers' insurance companies, in a recent notice to all policyholders makes the following statement: "We propose to advocate the heating systems for effective fumigation against the Mediterranean flour moth, weevil, and all other mill and grain infesting insects." The objection that the system is not practical because of the impossibility of heating in winter is one scarcely worth considering. No one is advocating the heating of a mill in winter. Any one familiar with the insect infestation of a mill knows that if a mill is heated during the latter part of the summer and all the insects killed, there will be no necessity for heating during winter months. The objection that heat will injure the belting, check the elevator legs and the woodwork of the bolters and purifiers is without a semblance of truth. In one experiment the mill was heated far above the required temperatures, some of the temperatures going as high as 150° F., for a period of nearly thirty hours, and the examination showed absolutely no injury to any part of the mill or the mill machinery.

SUMMARY OF RESULTS

In a mill, flour accumulates in recesses and insects breed in places inaccessible to the gas or vapor of any fumigating material, but heat passes through all of these obstructions and penetrates the innermost recesses! Many mill insects do not yield readily to hydrocyanic acid gas, but no mill insect can withstand for any length of time a temperature of from 118° to 122° F. The writer has fumigated many mills

with hydrocyanic acid gas, but in no case has the fumigation with gas proven so successful as the heating of several mills. In the heating of these mills it has been demonstrated that the heat is the most practical, efficient, convenient and least expensive method. To fumigate with hydrocyanic acid gas requires from two to three days, and this long shut down with the additional cost of material is a large item of expense, besides an element of danger to the operator, while with heat, since it can be applied from Saturday evening until Monday morning, there is no loss of time, very little expense, and no danger to the life of the operator.

TEMPERATURE RECORDS AND OTHER DATA OF SOME MILLS THAT HAVE USED HEAT SUCCESSFULLY

R. E. KIDDER FLOUR MILLS, KANSAS CITY, KANSAS

Capacity of mills, 600 barrels.

Building, brick.

Date of heating, July 7-8, 1912.

Character of day, partly cloudy and calm.

Outside maximum temperature, 91 degrees.

Outside minimum temperature, 73 degrees.

Heating system, steam pipes along the wall, except in space beneath the first floor where radiators are used.

Steam pressure maintained during the heating, about 20 pounds.

First Floor

Capacity of floor, 28,728 cu. ft. Amount of radiation 525 sq. ft.

No. 1.

Location of Thermometers

In 2 inches of flour in elevator boot on floor 8 feet beneath steam pipes. No. 2. Hanging in middle of room 5 feet high, 15 feet from steam pipes.

No. 3. In 2 inches of flour in elevator boot on floor, 12 feet from steam pipes. Result: Failed to reach killing temperatures in elevator boots on the floor, exce directly over radiators in space beneath the floor. Killing temperatures reached all other parts of the room.

Second Floor

Capacity of floor, 28,728 cu. ft. Amount of radiation 560 sq. ft.

No. 1.

Location of Thermometers

Hanging in open 4 feet high, 15 feet from steam pipes.
No. 2. Between rolls in roller, 11 feet from steam pipes.
No. 3. Hanging in open 6 feet high near roller machinery.
Results: One hundred per cent of the insects were killed.

No. 1. Hanging in open 5 feet high, 15 feet from steam pipes.
No. 2. In flour in conveyor near floor, 12 feet from steam pipes.
No. 3. In flour in conveyor 6 feet high, 15 feet from steam pipes.
Results: One hundred per cent of the iusects were killed.

Fourth Floor

Capacity of floor, 43,092 cu. ft. Amount of radiation 400 sq. ft.