June, 1954]
JAMES
N.
WARNER
AND
O.
P.
AGARWALA
111
Installing and assembling the faucet
The faucet is to be installed in the milk can in such a position that when the
can is upright and level the milk may drain completely from the can through the
faucet. To assure this the faucet should be fixed so the inside bottom surface of
the feed pipe is about one-eighth inch below the lowest point in the bottom of the
can, and at an angle of just over 90° to the vertical axis of the can. Some cans
have concave, some convex, and still others plane bottoms. The characteristics
of each particular can will determine the exact position of the faucet. It is advis-
able to locate the faucet at a point 90° around the can side from the position of the
can handles, if any, although this is not imperative.
The faucet plug is inserted in the faucet plug housing and the locking collar
fixed in position. The ring valve is then placed either over the milk outlet cone or
inside the ring valve housing, then the housing is screwed into position over the
threaded outlet pipe. A string or wire is then passed through the holes of the
tying bracket on the ring valve housing and the tying bracket on the plug locking
collar, which holes should be directly opposite each other with the brackets fitting
closely together when the faucet is fully assembled. This string or wire is then
tied and sealed with a wax or lead seal. If properly constructed and assembled,
there is no way of disassembling the faucet, while on the milk route or elsewhere,
without breaking this seal. Dairy operators are warned, however, that this seal
must be inspected very carefully on the return of the can from the route to make
as certain as possible that it has not been broken and then skilfully replaced.
Working of the faucet
As the faucet plug is opened, milk, if present in the can, will flow outward
through the threaded outlet and into the milk outlet cone. The pressure of this
flowing milk forces the ring valve outwards, allowing the milk to pass into the ring
valve cone-shaped opening, backward outside the milk outlet cone until it passes
the inside edge of the ring valve; the milk then flows outward through the grooves
along the outside of the ring valve and into the outer portion of the ring valve
housing; it then drains out of the faucet.
The physical characteristics of the plastic which is used for the ring valve
and the constructional features of this valve and its housing are such that valve
is very sensitive to the pressure of a flowing liquid, whether that liquid is flowing
in or flowing out of the faucet. As is stated, milk flowing outward through the
faucet activates this ring valve so as to allow the milk to pass. On the contrary,
if an attempt were made to force water inward through this faucet, as may be done
when attempts are made to adulterate the milk in the can by forcing water through
the faucet, this ring valve closes, thereby stopping the inward flow of the water.
The effective principle of this faucet is the construction and sensitivity of this
ring valve. Plastic was chosen because it is relative to milk much lighter than any
common metal that might be used for the purpose. A ring valve of hollow con-
struction, made of the gauge metal, might prove as sensitive to the movement of
milk, or water, as does this plastic valve. Such a ring valve, however, is extremely
difficult to construct satisfactorily.