Pneumatic Differentiator

[Green 123]

Pneumatic differentiator is a safety device which is fitted to a regulator& shut off control valve at upstream of pneumatic starter of gas turbine engine that is highlighted with red ellipse. Do you have any idea on its working principle?

 

[TugboatEng]

It has a piston and spring that push down on a ball. Air pressure down stream of the butterfly lifts the piston off the ball. The rate the piston moves is slowed by a needle valve. When the ball lifts it vents the actuator piston which closes the butterfly.

In short terms, it regulates the air pressure at the nozzle guide vanes.

 

[Green 123]

It has a piston and spring that push down on a ball. Air pressure down stream of the butterfly lifts the piston off the ball. The rate the piston moves is slowed by a needle valve. When the ball lifts it vents the actuator piston which closes the butterfly.

In short terms, it regulates the air pressure at the nozzle guide vanes.

much obliged