APPLICATION OF REFRIGERATION TO HANDLING OF MILK. 31 
should not be placed in the engine or boiler room, as the heat will 
evaporate part of the liquid and drive gas back into the condenser to 
be recondensed. Such an arrangement makes it necessary to install 
a larger condenser and to use more condensing water, and, in addi- 
tion, the liquid goes into the evaporating system carrying its full 
quota of heat, thereby reducing its value. 
The machine should be set on a well-built brick or concrete founda- 
tion, care being taken to have the machine perfectly level. 
Before making the pipe connections all dirt and scale should be 
removed from the inside of the pipe and a pipe die run lightly over 
all threads exposed during shipment, after which they should be 
thoroughly washed with gasoline or benzine. The pipe fittings 
should be cleaned in the same way before connections are made. 
After the pipe and fittings have been thoroughly cleaned, apply a 
paste of litharge and glycerin to the threads and screw the pipe 
fittings up tight. Where soldered joints are required the threads 
on the pipe ends and fittings should be heated and thinned with 
solder before they are made up. 
When the machine is in place and all pipe connections properly 
made, remove the cover of the crank case and fill with ammonia oil 
to the level of the crank shaft, or to the line on the frame of the com- 
pressor indicating the proper amount of oil required. 
Disconnect the by-pass piping and close the main suction and 
discharge valves. Run the machine under no-load conditions for 
two hours to smooth up the bearings and make any adjustments 
that may be found necessary; then connect the by-pass on the 
discharge side. (Some manufacturers provide plugs in the by-pass 
piping, in which case it is not necessary to disconnect the piping.) 
Open the main discharge valve and all other valves on the ammonia 
system except the main suction valve and the by-pass valves, which 
should be closed. 
Now start the machine again and pump air on the entire system to a 
pressure of about 150 pounds on the low-pressure gage. This should 
not be done, however, in one operation, on account of the possibility 
of melting the joints, due to the heat contained in the air. During 
the operation the machine should be stopped from time to time 
and all the apparatus examined in order to see that no undue heating 
occurs. Should parts of the apparatus be found unduly hot, the 
machine should remain at rest until the heated part is sufficiently 
cooled. Stop the machine and examine all piping and connections 
for leaks. This can best be done by applying soapsuds with a brush 
to all connections, and if there are any leaks they will be indicated by 
bubbles. If there is an ice-freezing tank in connection with the 
system, run water into the tank, completely submerging the coils, 
