What does the inverted triangle in the solenoid valve symbol stand for?

Pilot valve. According to the query electrician official website, the inverted triangle represents the pilot valve, and the positive T indicates that this road is blocked. Solenoid valve symbol refers to the schematic diagram describing the function of solenoid valve, which is applied to the design of pneumatic system and product identification, providing designers of pneumatic system and solenoid valve users with an understanding of product function.