26 
BULLETIN 1375, U. S. DEPARTMENT OF AGRICULTURE 
Table 4. — Correct sizes of gas pressure regulators for moisture tester or testers 
having various number of burners, varymg sizes of gas supply lines, and the 
minimum gas pressure on the supply line at which the regulators will 
operate 
Size of regulator 
Required 
size of 
supply pipe 
(inside 
diameter) 
Minimum 
Number of burners 
Inside 
diameter 
of inlet 
and outlet 
Trade desig- 
nation 
pressure 
at which 
regulator 
will operate 
2 -. 
Inches 
% 
% 
M 
l 
l 
IK 
IK 
5-light 
do 
do 
10-light 
do 
30-light 
do 
Inches 
Vi 
K 
% 
1 
1 
IK 
IK 
Inches 
0.3 
4 --. 
.3 
6 .- 
.3 
12 
3 
18 .- 
.3 
24 
3 
30 
3 
Note. — Gas pressure measured in inches head of water. 
HOW TO ADJUST A GAS PRESSURE REGULATOR 
After the pressure regulator has been installed on the supply line 
as near to the tester as possible it must be adjusted to give a standard 
heating time. The following method of procedure in making such 
an adjustment is necessary : 
(1) Overhaul the moisture tester thoroughly by: 
(a) Replacing all cracked or burned-off wire gauzes with new 
ones and adjusting them so that the flame will strike the asbestos 
center of the gauze. 
(b) Adjust the asbestos ring of the flask rest so that the bottom of 
the flask is approximately three-eighths inch above the wire gauze. 
(c) Take down each burner and clean it thoroughly. In this oper- 
ation special care should be given to the cleaning of grids in the top 
of the burner, the needle hole in the burner base, and the burner 
valve. 
(d) Test all gas connections for leaks, and if any are found tighten 
or replace the fittings. 
(2) Determine the gas pressure on the supply line of the tester or 
testers when all burners are in operation, by the use of a pressure 
gauge connected to the supply line and which will register gas pres- 
sure in inches head of water. To do this, throw the regulator out of 
operation by pressing down the valve in the top. 
(3) With the pressure gauge still connected to the supply line and 
all burners in operation, release the valve of the regulator. 
(4) Place a weight on the valve that will set the regulator to 
deliver gas at a pressure of approximately 2.5 inches less (as deter- 
mined by readings of the pressure gauge) than the gas pressure as 
determined in item 2 above. 
(5) Make a preliminary heating time test (oil test) on every com- 
partment of the tester or testers, with the flasks containing 450 cubic 
centimeters of oil alone and the mercury bulbs of the thermometers 
completely buried in the oil, as described on page 22. If the 450 
cubic centimeters of oil in all compartments heat to 175° C. in less 
than 20 minutes, place a lighter weight on the valve in the regulator. 
Repeat the tests, adjusting the weight on the regulator after each 
