Trap (siphon) and gas lamp: what they have in common
Step 1.
Trap (siphon)
— is part of —
Flush toilet
. A trap.
Step 2.
Flush toilet
— has part —
Valve
. The cistern’s float valve.
Step 3.
Valve
— is part of —
Gas lamp
. A gas supply valve.
Open Evothings