For a DOT 3HT oxygen cylinder to be eligible for recharging, when must it have been hydrostatically tested?

For a DOT 3HT oxygen cylinder to be eligible for recharging, it must be hydrostatically tested every 5 years. This testing is crucial as it ensures the cylinder is capable of safely holding high-pressure oxygen, which is particularly hazardous if the cylinder has structural integrity issues.

Hydrostatic testing involves filling the cylinder with water and subjecting it to pressures higher than it would normally encounter during use. This process checks for any leaks or weaknesses in the cylinder material, ensuring it remains safe for recharging and subsequent use.

By adhering to the 5-year testing requirement, users can maintain compliance with safety regulations and ensure that their oxygen cylinders are fit for service, minimizing the risk of accidents or failures during operation.