1 Role and composition of air seal set
1.0.1 Role
1.0.1.1 In order to prevent the materials in the storage tank from being polluted or deteriorated due to contact with the external gas (air) or from chemical and/or biological reaction with the external gas (air), it is often necessary to set an air seal system. The seal gas is used to maintain a certain pressure (positive pressure) in the storage tank to prevent the materials in the storage tank from contacting with external gas.
1.0.1.2 When the materials stored in the storage tank are pumped out and/or the gas in the storage tank is condensed or contracted due to the decrease of the external temperature, the system automatically fills in seal gas to prevent the external gas from entering; when the pressure in the storage tank is higher than that of the air seal due to that materials are fed into the storage tank and/or the liquid in the storage tank is vaporized due to the increase of external temperature, the gas in the storage tank can be automatically exhausted into the atmosphere via the pressure relief valve.
1.0.1.3 Common seal gases include nitrogen, fuel gas, natural gas, etc. The seal gas shall be selected according to the nature of materials stored, the difficulty in obtaining the seal gas and its economy.
1.0.2 Composition of air seal set
1.0.2.1 See Figure 1.0.2-1 for the air seal set. It consists of four parts: air seal valve (also called main valve), signal valve (also called control valve), pressure reducing valve and needle valve.
1 Role and composition of air seal set
2 Selection and calculation of air seal sets
