ASTM D3701 Test Method for Hydrogen Content of Aviation Turbine Fuels
5. Apparatus
5.1 Nuclear Magnetic Resonance Spectrometer - A low-resolution continuous-wave instrument capable of measuring a nuclear magnetic resonance of hydrogen atoms, and fitted with:
5.1.1 Excitation and Detection Coil, of suitable dimensions to contain the test cell.
5.1.2 Electronic Unit, to control and monitor the magnet and coil and containing:
5.1.2.1 Circuits, to control and adjust the radio frequency level and audio frequency gain.
5.1.2.2 Integrating Counter, with variable time period in seconds.
5.2 Conditioning Block - A block of aluminum alloy drilled with holes of sufficient size to accommodate the test cells with the mean height of the sample being at least 20 mm below the top of the conditioning block (see Fig. 1).
5.3 Test Cells - Nessler-type tubes of approximately 100-mL capacity with a nominal external diameter of 34 mm and a nominal internal diameter of 31 mm marked at a distance of approximately 51 mm above the bottom of the tube by a ring around the circumference. The variation between the internal diameters of the test cells used for the sample and reference material should not be greater than ±0.5 mm.
NOTE 1 - To avoid potential difficulties with tightness when the test cell is introduced into the magnet coil, users are cautioned to avoid test cells that have nominal external diameters that are greater than 34.2 mm.
5.4 Polytetrafluoroethylene (PTFE) Plugs for Closing Test Cells - Plugs as shown in Fig. 1 made from pure PTFE and a tight fit in the test cells.
5.5 Insertion Rod - A metal rod with a threaded end as shown in Fig. 1 for inserting and removing PTFE plugs from test cells.
5.6 Analytical Balance - Top pan type, capable of weighing the test cells in an upright position to an accuracy of ±0.01 g.
6. Materials
6.1 Reference Standard - Dodecane, 99 mass % minimum purity (Warning - Flammable.).
7. Sampling
7.1 Take a homogenous sample in accordance with Practice D4057.
