Operating instructions

8. Version for Hg determination in natural gas and other hydrocarbon gases (Tedlar®
Bag Version) page 86
Mercury Instruments UT-3000-E_V2.11.docx 31.07.12
Analytical Technologies
8.3.2 Sampling of natural gas with the sample bag (Tedlar® bag)
The sample bag has to be completely empty before filling with sample gas. This may be done by
opening the valve of the bag, placing the bag onto a smooth and clean surface and running the
back of the hand over the bag until it is totally flat. Filling must be done by connecting the
sample bag with a source of positive pressure. Open the valve of the bag by turning its upper
portion counter-clockwise one revolution. It has under all circumstances to be avoided that air
can enter the sample bag because this could lead to formation of an explosive mixture in the
sample bag. For this reason do not use a pump for filling the bag. Do not inflate the bag too
much, avoid filling the bag more than 80 % of its maximum volume. Close the sample bag by
turning the upper portion of the valve clockwise until it is snug. Observe operating instructions
coming with the sample bags.
Transportation of the gas filled sample bag
Be careful when handling or carrying a filled bag as it contains flammable gas. It must be
avoided that air can enter the bag. Use smaller bags (for example 3 litre bags) whenever possible
to minimise risk. Keep the filled bag away from any ignition source.
8.3.3 Measuring the sample from the bag
After the instrument has been switched on and warmed up the user is asked to enter the sample
name. Use the numerical keys (0-9) to enter letters or numbers, use the left arrow button for
delete or the up arrow buttons to move the cursor right. Enter letters first and press ENT, then
enter numbers and press ENT if finished. With the F1 key the previous sample name can be
recalled.
A message on the display tells the operator to connect the sample bag and to open the sample bag
valve. Place the sample bag in front of the analyzer on the same table. Connect the sample bag to
the sample gas inlet nozzle of the UT-3000 analyzer using the Tygon tubing which has been
delivered with the instrument. The bag should be placed onto the same table where the analyzer
is set in order to avoid that it may disconnect from the analyzer thus causing a leak. Now open
the valve of the bag by turning its upper portion counter-clockwise one revolution.