Why is the depressurization valve only connected on the Backup Pump?

Why is the depressurization valve only connected on the Backup Pump?

• A. to reduce output pressure of the pump upon startup of the electric motor
• B. to increase output pressure during startup
• C. to vent air from the system
• D. to provide a bypass path for leakage

Answer: (A)

The main idea is to limit the surge in hydraulic pressure when the backup pump (the electric-driven one) starts. When the electric motor comes up to speed, the pump would otherwise deliver a rapid rise in pressure. The depressurization valve bleeds off some flow, keeping the output pressure lower during startup so the system isn’t subjected to a sudden, potentially harmful pressure spike. Once the pump reaches normal running speed, the valve stops relieving pressure and full pressure is available. This is specifically on the Backup Pump because the primary, engine-driven pump is already properly regulated for normal operation and doesn’t require this startup-limiting feature. It isn’t primarily used to vent air, increase pressure on startup, or provide a leakage bypass.

The main idea is to limit the surge in hydraulic pressure when the backup pump (the electric-driven one) starts. When the electric motor comes up to speed, the pump would otherwise deliver a rapid rise in pressure. The depressurization valve bleeds off some flow, keeping the output pressure lower during startup so the system isn’t subjected to a sudden, potentially harmful pressure spike. Once the pump reaches normal running speed, the valve stops relieving pressure and full pressure is available. This is specifically on the Backup Pump because the primary, engine-driven pump is already properly regulated for normal operation and doesn’t require this startup-limiting feature. It isn’t primarily used to vent air, increase pressure on startup, or provide a leakage bypass.