Hewlett Packard 5710A Gas Chromatograph
Updated 26 May 2018
Dual PEM Fuel Cell Electroliser
The HP5710 Gas Chromatograph has been modified to run off two PEM fuel cells used as electrolisers of water. One fuel cell supplies hydrogen as a column carrier gas. The other larger fuel cell supplies hydrogen as a make-up gas to assist combustion in the flame ionisation detector. Air is added to the flame ionisation detector from a small aquarium pump connected to a regulating valve. This stabilises the flame.
A gas chromatograph sorts out gas mixtures according to the delay in passing through a chemically treated column. This delay is called the retention time. Heavier molecules tend to have longer retention times.
A heated inlet with a silicone rubber septum is used for introducing sample mixtures held in a small syringe. The sample mixture passes along the column driven by the hydrogen carrier. The mixture gradually separates into its component parts.
At the far end of the column the make-up hydrogen is added. All the hydrogen is burnt in the flame ionisation detector. When any hydrocarbons arrive, the flame produces ionisation which causes the flame to conduct electricity. The voltage bias required is usually about 250 volts. The signal is amplified and presented to the data logger.
The fuel cells can be obtained here
The air flow from the aquarium pump is increased until the flame goes out with a pop. The valve is then backed off a little from this setting for sustained use.
The fuel cells are all hydrated from a single water tank supplying the oxygen side of each fuel cell. The lower and upper ports are connected to the tank at corresponding levels. The fuel cells are continuously hydrated as bubbling of oxygen only occurs at the upper ports. A syringe can help to initially draw water through if bubbling occurs at the bottom. Thereafter the water is circulated with the released oxygen.
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HP5710A Gas Chromatograph.
TabDVM ion plot.