Sanitary rotary pumps typically use the following sealing methods:

1. Mechanical seal: A mechanical seal is achieved by the contact between two relatively moving sealing surfaces, usually consisting of a fixed sealing ring and a rotating sealing ring. This sealing method is suitable for strict hygiene level applications and can effectively prevent medium leakage, but requires regular inspection and maintenance.

2. Packing seal: Packing seal is a sealing material filled between the pump shaft and the sealing shell, which is sealed by compressing the packing material. This sealing method is simple and cost-effective, but requires high selection and maintenance of fillers, and is easily affected by the medium.

3. Unidirectional mechanical seal: Unidirectional mechanical seal is a special type of mechanical seal commonly used in high hygiene applications. It prevents media from entering the sealing area between the pump shaft and pump casing by installing a one-way mechanical seal at the feed end of the pump, thereby maintaining the cleanliness of the pump.

4. Air gap sealing: Air gap sealing is achieved by using the small gaps between the internal components of the rotor pump to achieve sealing, and is usually used in some applications that do not require strict hygiene standards. This sealing method is simple and cost-effective, but the sealing effect is relatively poor and is easily affected by the properties of the medium and working conditions.

In general, the sealing method of sanitary rotary pumps should be selected based on specific process requirements and application scenarios to ensure the normal operation of the pump and the safety of the medium.