In the POC calculations, which variable represents the pilot pressure?

• A. Poppet area
• B. Pilot pressure
• C. Load pressure
• D. Port size

Answer: (B)

In piloted valve calculations, the action is governed by a force balance on two sides: the pressure acting on the small pilot area and the pressure trying to keep the main poppet closed. The pilot pressure is the pressure that acts on the pilot surface to generate a lifting force. It is the variable you adjust in the calculations to determine when the valve opens. This pilot-induced force must overcome the closing force from the load pressure acting on the main poppet area (and any spring). So the term that represents the pressure used to operate the pilot is the pilot pressure. Poppet area and port size are geometric factors that influence how much force a given pressure can produce, while load pressure is the pressure on the downstream side that the valve must overcome to open.