Where do the higher and lower pressures of the two safety valves on the ammonia tank come from?

The difference in pressure between the two safety valves on an ammonia tank, with one having a higher pressure and the other a lower one, is usually caused by variations in the spring strength or setting of the opening pressure of the two safety valves. If different set opening pressures are configured, then when the pressure inside the tank rises to the opening pressure of the lower-pressure valve, only that safety valve will open. The pressure continues to rise until the high-pressure valve opens. If the spring strengths are set differently, then at the same opening pressure, the spring of one valve may be looser than that of another, causing this valve to open first. Regarding the issue of both safety valves needing to be opened simultaneously, this is actually not necessary. Normally, as long as one safety valve meets the requirements, the other serves as a backup. The second safety valve will come into action only when the first one fails. In this case, the spring of the second safety valve relaxes, allowing gas to be discharged smoothly and keeping the pressure within a safe range. .

The set pressures for high-pressure safety valves and low-pressure safety valves are usually determined by design requirements or relevant standards. The set pressure of a high-pressure safety valve is generally higher than that of a low-pressure safety valve, in order to handle potential high-pressure situations. Under the current setting of equal pressure, this may be due to certain specific considerations. For example, operational requirements, system design, or security requirements. Such a design can prevent one of the safety valves from opening prematurely or ensure even pressure distribution. As for whether both safety valves need to be opened simultaneously, this depends on the specific system requirements and design. In some cases, both safety valves may open simultaneously to enhance system safety and prevent the failure of a single safety valve. However, in other cases, it is sufficient for only one of the safety valves to open to meet the safety requirements.