The liquid level lines commonly used by our company are generally Φ22 and Φ30. Φ22 is installed on the die head. Φ30 is installed on the plasticizing system. It can be installed later. For a single die head machine, change the die head body, install a penetrating ring, add a throttle plug and throttle plug seat, and install an extrusion system. For a multi-die machine, the die body, penetrating ring, throttle plug and throttle plug seat need to be multiplied by the corresponding number of die heads.