2 BULLETIN 890, TJ. S. DEPARTMENT OF AGRICULTURE. 
3. Ease of sterilizing. — Some types of machinery are much easier 
to get at for steaming than others. All apparatus in which milk is 
handled must be sterilized daily with live steam ; hence the item of 
" inaccessibility " should not be overlooked. 
4. Initial cost. — Machinery should not be purchased on the basis 
of cheapness alone; it is often economy to purchase some of the 
highest-priced machines. The initial cost, however, must be con- 
sidered and weighed against all other factors. 
5. Rapidity, ease, and economy of operation. — A study of the 
machinery in actual operation is necessary to determine these factors. 
6. Avoidance of rubber gaskets and fittings. — All fittings in milk- 
handling equipment, so far as possible, should be of metal. 
7. Proper capacity. — The equipment purchased should be of suffi- 
cient size to handle all probable increase of business ; but it should be 
borne in mind that plant equipment depreciates rapidly, and it is 
not advisable to procure oversize apparatus which will not last until 
the anticipated increase has taken place. 
8. Durability. — Cheap machinery often wears out or gets out of 
order in a very short time. It is more economical to purchase a well- 
constructed and durable machine even if the initial cost is somewhat 
higher. 
The life of milk-plant equipment and machinery will depend upon 
the original condition, amount of use, and the care given it. As a 
rule such equipment receives hard and constant usage and depreciates 
quite rapidly. The average annual depreciation of all milk-plant 
equipment in 69 plants varied from 4 to 33J per cent, with an average 
of 14.6 per cent. The annual per cent of depreciation of the various 
items of equipment in 20 other plants was as follows : 
Table 1. — Depreciation of various items of equipment in 20 plants. 
Type of machinery. 
Annual 
deprecia- 
tion. 
Variation. 
Per cent. 
18.2 
17.2 
18.8 
9.4 
20.0 
Per cent. 
10-30 
10-20 
10-30 
5-15 
15-30 
At 12 of these 20 plants the depreciation was 20 per cent on fillers 
and cappers, bottle washers, and pasteurizers, while at 8 of them the 
depreciation on power-plant equipment was 10 per cent, these figures 
being the most common. 
It may be safely estimated that at the average plant the milk- 
handling equipment depreciates nearly 20 per cent, or, in other 
