BALLOON INFLATION AND ASSEMBLY OF TRAIN B3-5 
3.2 Positioning Balloon for Inflation. Place the balloon in a position 
where it will not come in contact with sharp objects or rough surfaces, 
If the dimensions of the inflation shelter permit, the balloon should be 
placed on a table for inflation. The table top should be very smooth, free 
from projections of any sort, with alledges rounded and the top covered 
with talc. The table top should be cleaned frequently and a new coat of 
talc applied. The table should be large enough so that the balloon can be 
fully extended before inflation is started to reduce abrasion during infla- 
tion. If it is not practicable to use a table, then the balloon should be 
placed on a clean sheet of paper large enough to keep the balloon off the 
floor. Remove any objects with sharp points from the immediate vicinity 
of the balloon and smooth all edges on the inflation weights and nozzle. 
Wrap the loops on the handles of the inflation nozzle clamps with tape. 
Place the inflation nozzle in the neck of the balloon and secure it with a 
clamp or soft cord. 
3.3 Rate of Inflation. Inflate the balloon at a sufficiently slow rate to 
insure a uniform expansion of the film. If the gas regulator or outlet 
valve is equipped with a low-pressure gage, open the valve to a pressure 
not exceeding 20 pounds per square inch whenusing helium, When a low- 
pressure outlet gage is not available, adjust the flow of gas so that a 
period of 12-15 minutes is required to inflate the balloon completely. 
When hydrogen is used, open the valve to a pressure not exceeding 10 
pounds per square inch. If the balloon is rapidly inflated with hydrogen 
gas, the likelihood of generation of static electricity is greatly increased 
and with it the hazard of fire or explosion. 
3.4 Checking for Leaks. When the balloon is about one-half inflated, 
close the gas valve. Listen for gas leaks and examine the balloon for de- 
fects. Serious defects may result from foreign material in the rubber, 
a break in the balloon skin, or a deformity in a small area of rubber 
film. Discoloration should not be regarded as a defect unless ex- 
perience indicates that certain types of discolorations result in pre- 
mature bursting. If the balloonis defective, rejectit and begin preparing 
a second balloon; otherwise, proceed with inflation. Close the outlet 
valve as soon as the inflation weights are raised from their support. 
Again listen momentarily for escaping gas from the balloon, If a leak is 
detected, reject the balloon. 
3.5 Constant-Rate Inflation. When a balloon cannot be completely in- 
flated with the inflation nozzle resting on a table because the balloon is 
likely to touch the ceiling, move the nozzle to the floor and continue the 
inflation. If the balloon is still likely to touch the ceiling before the de- 
sired lift has been reached, protect the balloon from damage by stretch- 
ing a net below the ceiling, or by padding the ceiling with some soft ma- 
terial, Then proceed as follows: 
io SO) FMH#3 
