128 U. § BUREAU OF FISHERIES 
to furnish detailed plans and specifications for a typical sardine 
drier. There are presented, however, in this paper sufficient data 
to enable engineers to design drying equipment for preparing fish for 
cooking in hot oil, hot brine, or steam. Information also is given 
that should enable a canner to operate such equipment with the best 
results. 
The following recommendations of a technical nature are made 
regarding the equipment: 
1. Air velocity—About 2,000 feet per minute throughout the 
free spaces of the equipment. 
2. Air temperature.—Desirable possible variation in entering alr, 
90° to 160°. Permissible drop in temperature under operating 
conditions when entering air at 150°, about 20°. Average operating 
temperature should be about 140°. 
3. Air quantity —Sufficient to meet conditions imposed in 1 and 2. 
4. Drying time.—Fifteen minutes; means to be provided for 
varying speed of conveyer so that time can be varied from 10 to 30 
minutes as desired. 
5. Heat supply—Any approved method of heating the air is 
satisfactory, the cheapest to install and operate being preferred. 
Direct products of combustion from gas and oil fired furnaces operating 
without smoke are satisfactory. 
6. Type of equipment.—Similar to the regular California ‘‘multi- 
apron”’ drier described elsewhere in this publication. In passing 
from one ‘‘apron”’ to another a fall of 8 to 10 inches or less is satis- 
factory for pound-oval size fish. Means should be provided for 
recirculating some or almost all of the air that leaves the drier, as 
desired, same to be easily controlled. 
7. Weight of fish per unit of drying surface—Assume that each 
square foot of wire screen surface in use at any one time for holding 
fish will handle 1.8 to 2 pounds of ‘‘cut”’ fish. (See p. 155.) 
It will be necessary for the canner to furnish data upon the size 
(if different than given above) and quantity of fish to be handled per 
hour, the space available for the drier, and the manner in which the 
fish are to be handled to and from the drier. 
It is not advisable to attempt to outline detailed instructions for 
preparing the fish. Their size and condition and other factors are 
constantly varying. To meet this variation changes must be made 
in drying conditions. Just what to do under the various circum- 
stances must be learned by experience. In general, however, the 
air velocity and temperature used should be as high as possible, so 
that the drying time can be reduced to a minimum. The air velocity 
can not be increased much above 2,000 feet per minute without 
encountering difficulty from the fish being blown about. Caution 
must be used in raising the temperature of the air. If the wires 
touching the fish get too hot, they tend to cook the skins, and when 
these fish are placed in hot oil the skins will break badly. Little 
trouble will be met if the air temperature does not rise much above 
140°. As much of the air leaving the drier as possible should be 
recirculated, otherwise there will be excessive heat losses. 
The efficiency and capacity of driers now in use can be increased 
greatly by mak ng such changes as will permit the drying conditions 
recommended above to be realized. I have never examined a 
commercial sardine drier that prepares fish for frying in oil that 
