The suction inlet of the breather valve is connected to nitrogen – what is the maximum pressure of nitrogen? If the nitrogen pressure is 0.5 Mpa, is it necessary to install a pressure regulator on the nitrogen pipeline? If necessary, how low should it be reduced?

It can be used at 0.6 to 1.0 MPa

Thank you. Can a shut-off valve be installed on the nitrogen pipeline?

A pressure reducing valve is required; this valve reduces the pressure to the level appropriate for use in the storage tank

This pressure should be determined based on the operating pressure inside the storage tank. Personally, I think a pressure of 0.5 MPa is a bit high; a pressure regulator would be necessary

I think these are two separate issues: 1. The breathing valve can handle pressures of 0.6–1.0 MPA. 2. The pressure setting for the storage tank needs to be determined based on requirements and economic considerations; for example, if various users require nitrogen at a pressure of 0.5 MPA, then the pressure in the storage tank must not be lower than 0.5 MPA. 3. A shut-off valve can be installed on the nitrogen pipeline, but generally no shut-off valve is placed before the breathing valve – it is connected directly to the breathing valve； If it must be installed, use a ball valve or gate valve that is normally open.

In other words, if it is a pressure-vessel at normal pressure, then the nitrogen pressure needs to be reduced to a few thousand pascals; is the nitrogen pressure related to the actual pressure of the vessel?

If a nitrogen seal is required for the storage tank, it is not recommended to connect nitrogen directly to the inlet of the breather valve. The nitrogen sealing system includes: a nitrogen sealing valve, a nitrogen release valve, and a breather valve ； It is a self-acting micro-pressure control system; the nitrogen seal pressure typically ranges from 0.5 to 2 Kpa. The nitrogen seal valve functions as a pressure reducing valve as well – usually, the pressure before the valve is less than 1 MPa, while the pressure after the valve is 0.5 to 2 Kpa, and this value can be adjusted. If the pressure before the valve is greater than 1 MPa, an additional pressure regulator may be needed to reduce the pressure to below 1 MPa ； With a nitrogen seal in place, the breather valve normally does not operate; it comes into use only when the nitrogen seal valve or the nitrogen release valve fails. The discharge pressure setting of the breather valve is usually higher than the pressure setting of the nitrogen release valve, while the suction pressure setting is lower than the pressure setting of the nitrogen seal valve ； A safety valve can also be installed on the storage tank or behind the nitrogen seal valve, with the set pressure being lower than the design pressure of the tank.

Yes, I’m a bit confused. 1. If it’s a pure nitrogen storage tank, the nitrogen is intended for use by downstream users; the pressure in such tanks is relatively high. Typically, the design pressure for nitrogen in factories is between 0.8 and 1.2 MPa, while the operating pressure is 0.6 MPA, so this pressure level is necessary. 2. If the tank stores another type of medium and nitrogen is only used as a sealing gas, then the saturated vapor pressure needs to be taken into account; generally, a pressure of a few thousand pascals is sufficient