NIC-TD-0000025-00
5. MENU screen
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(5)
Inject the gas into the Tedlar bag through the septum within three minutes.
(6)
After the PS-4 pump has stopped close the cock and disconnect the Tedlar bag
and septum.
Method of calculating the concentration of a standard mercury gas
The following information is needed in the calculation:
Temperature of the gas box when the gas was sampled
Amount of gas sample in the syringe
Amount of Air injected into the Tedlar bag
Use of the gas density table with a gas box temperature of 25°C, for example, means
that 19.9 ng/mL of mercury gas has been sampled. The amount of gas sampled is 3
mL, and the amount of gas injected into the Tedlar bag is 3 L when the gas flows from
the PS-4 at 1 L/min for 3 minutes.
Consequently, a standard gas of 0.020 mg/m
3
(= 19.9 ng x 3 mL / 3 L) has been
prepared in the Tedlar bag.
The concentration of a standard gas sample can be increased by increasing the
amount of gas injected, but should be limited to at most 0.099 mg/m
3
.
Open the cock
