CITY MILK PLANTS: CONSTRUCTION AND ARRANGEMENT. 31 
STEAM. 
It is important that all milk-handling equipment be sterilized im- 
mediately after washing, and plenty of live steam must be available. 
A convenient arrangement is to have a valve connected with the city 
water and with the steam system. By the use of such connection 
either hot or cold water or steam is made available. (Hot water can 
be obtained by turning on both the water and steam valves.) 
VENTILATION. 
Good ventilation is essential in a milk plant in order to get rid of 
the bad air and moisture and to insure pure air. In many plants the 
ventilation is inadequate, often being obtained by means of windows 
and doors only. It is difficult to get good ventilation by this method. 
Even in a medium-sized plant exhaust fans should be used to take 
out the bad air and moisture. Many modern plants have an arti- 
ficial system of ventilation by which air as pure as can be obtained 
is drawn through a filter or through a spray of water and then forced 
by fans through flues into the rooms. The openings from these flues 
or ducts into the rooms may be near the ceiling or near the floor, but 
usually they are about midway between. By heating or cooling the 
spray of water the temperature of the air in the rooms may be con- 
trolled to a certain extent. 
In large plants the process of filtering air consists in forcing it 
through one or more thicknesses of cheesecloth, or cloth and absorb- 
ent cotton. The air is forced into the room through the filter under 
a small pressure, so that the used air has a tendency to pass out- 
ward through the openings near the ceiling provided for outgoing 
air. All air coming into the room must pass through the filter, which 
should be changed often. At some plants before the air is forced 
into the rooms it is cooled in summer by passing over brine coils and 
warmed in winter by passing over steam coils. 
For a medium or small plant there should be some system of arti- 
ficial ventilation. A flue system similar to that used in dairy barns 
is quite efficient and is not expensive. By simply installing outlet 
flues through which the air can pass out and allowing air to come in 
through the windows, fairly good ventilation can be obtained. 
In many plants the cold-storage room is very poorly ventilated. 
It is, of course, impracticable to have open windows in this room; 
consequently if an artificial system of ventilation is not used the 
ventilation is poor and the best results are not obtained from the 
cooling coils. There is also a condensation of moisture on the ceiling 
and a constant dripping, which is very uncomfortable and insanitary. — 
In plants where artificial ventilation is impracticable considerable 
improvement can sometimes be made by using’ an ordinary electric 
