Via the small pipe connected to the vent which goes to a "safe area for venting". If a small amount of vapour, often min 3 m high.
Vents have a zone around them for electrical rating purposes (exploison proof etc)so it can affect more things than you think if you just vent locally.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
In a plan 11, it's recommended that you plug your tubing from discharge at the highest point of your seal's cartridge, so you can vent your pump at the start up.