-
２９
-
①
Drawing raw gas
Connect a gas bag to an isobutane 99vol% cylinder and draw a
little more than you actually need.
Bend back the hose and pinch with a pinch cock so the gas does
not leak from the bag.
②
Drawing a fixed amount of raw gas
Connect a 10ml syringe to a gas bag and draw 7.2ml of raw gas.
(Draw a little more than you actually need then discharge the
excess.)
③
Transferring raw gas into a quantitative pump
Connect a syringe to the inlet of a quantitative pump then pull out
the pump’s piston. Raw gas in the syringe is sucked into the pump.
Remove the syringe and pull the piston all the way out (100ml).
④
Making diluted gas
Connect an empty gas bag to the outlet of the quantitative pump
then push in the pump’s piston.
Move the piston back and forth nine times to add air in order to
make diluted gas.
Fig. 18 Making Standard Gas
from Raw Gas
If you take 7.2ml of raw gas and move the quantitative pump’s
piston back and forth ten times (a back-and-force motion:
100ml),
7.2ml/(100ml×10)=0.0072
0.72vol% diluted gas is made.
Isobutane’s lower explosive limit (LEL) is 1.8vol%.
0.72/1.8×100=40
40%LEL diluted gas is made.
MEMO
Fig. 18 Making Standard Gas
from Raw Gas
純ガスボンベ
（立てて使用します）
ビニールチューブ
①
生ガスの入った
ガスバッグ
1ml
の生ガス
引く
注射器
②
注射器
定量ポンプ
③
定量ポンプ
空気
希釈されたガスの
入ったガスバッグ
④
pure gas cylinder
(Keep it upright.)
gas bag with raw
gas
7.2ml of raw gas
syringe
pull
syringe
quantitative
pump
air
gas bag with
diluted gas
vinyl tube
quantitative
pump
