Special fittings with nonstandard threads are used to prevent use of incorrect equipment with the cylinders. Although cylinders can be purchased, they are usually rented and then returned to the supplier for recharge at a nominal fee. High pressure gas cylinders should never he dropped or mishandled. When cylinders are not in use the cap should be kept on to protect the cylinder valve. Figure 10 Schematic diagram of gas pressure feed system.
Propellants are a liquid fuel and gaseous oxygen.
P is pressure gauge. Gaseous Nitrogen Nitrogen is an inert gas compatible with all normally available materials. The amateur builder will have little dificulty with materials of construction for nitrogen but must be careful that all components are suitable for high pressure service. Cleanliness of components is important for proper and reliable operation, Gaseous Oxygen Oxygen will not itself burn but does vigorously support the rapid combustion of almost all other materials. All items, including lines, fittings, valves, regulators, etc., MUST be absolutely free from oil, grease, and similar contaminants.