Definition
A valve in a vacuum-driven instrument system that maintains a constant level of suction (negative pressure) supplied to the gyroscopic instruments, regardless of variations in engine speed or pump output. It does this by allowing a controlled amount of outside air to bleed into the system when suction exceeds the set value.
Plain English
A device that keeps the vacuum pulling on the gyro instruments at a steady level, so they spin at the right speed even when the engine RPM changes.
Context Anchor
Seen in discussions and diagrams of venturi tube systems and vacuum-driven flight instruments.
Derivation
Regulator' comes from the Latin 'regula' meaning 'a rule' or 'straight stick used as a measure.' A regulator is anything that holds a value to a set rule or standard. Here, it holds suction to the standard required by the gyros.
Why Pilots Care
Prevents damage to instruments from excessive suction and avoids erratic readings from insufficient suction.
Intuition Check
A suction regulator does not create the suction. It controls the amount of suction already being produced by the system.
Example Sentence 1
During the runup, the pilot checked the vacuum gauge and confirmed the suction regulator was holding the system within the green arc.
Example Sentence 2
During the engine run-up the suction regulator kept the vacuum reading within limits despite the increase in RPM.