16 
BULLETIN 1315, U. S. DEPARTMENT OF AGRICULTURE 
ably three-fourths inch. Cases are known where from two to four 
machines have been attached to a ^-inch su pply l me > an d in 
every case serious errors have resulted in the moisture-test results. 
The errors were the result of an insufficient supply of gas to the 
burners when more than one machine was operated at the same 
time. 
The installation of gas supply pipes for moisture machines de- 
pends to a large extent upon where the moisture machines are to be 
located in the laboratory. They should be installed in a place where 
they will not be exposed to air currents. If 
the moisture machines are placed so that they 
are all in the same direction, the size of the 
gas pipes or manifolds on each machine should 
each, in a general way, be of a different size. 
For example, if four machines are to be placed 
in a line, the machine nearest the supply line 
should have a manifold iy± inches inside di- 
ameter, the machine next in line should have a 
1-inch manifold, the next machine a %-inch 
manifold, and the last machine also a %-inch 
manifold. Of equal importance is the capac- 
ity of the pipe line from the meter. Under 
no consideration should this be smaller than 1 
inch, and for a set-up as described above this 
pipe should be not less than iy 2 inches. 
In some laboratories it is not possible to 
place all the machines in one line. In such 
cases they are usually placed in a formation 
at right angles to the supply line. Under 
these circumstances the main supply line 
should b% larger than in the set-up mentioned. 
With testers in an angular position, each ma- 
chine should be supplied by a %-inch pipe, 
and these should each be tapped into a 2y 2 - 
inch main-line pipe. It is of further de- 
cided advantage to eliminate as many 
angles, turns, and tappings as possible on the 
main supply line ; that is, the meter line. No 
particular advantage appears to accrue from leading a supply 
pipe to both ends of the manifold. 
BURNERS 
It is not essential to have any particular type of burner for gas- 
heated machines. Almost any burner having a diameter of 20 milli- 
meters and 130 millimeters in height will suit the purpose. The 
important thing concerning any burners that are used is that, after 
being once adjusted, they stay adjusted to give off a uniform quan- 
tity of heat. When Meker burners are used the burners should be 
equipped with wing-nut set screws placed on the burner to anchor 
the air valve to any desired position. When Bunsen burners are 
used they should be equipped with set screws for both the air and 
gas valves. 
Fig. 15. — Oil-recovery and 
oil-storage cans 
