The tell-tale hole for the stem O-ring is located on which part of the SOPV?

• A. Inside the control panel
• B. Top of the pump
• C. Rim of the service tank
• D. Side of valve body on SOPV

Answer: (D)

A tell-tale hole is used to provide an external sign of leakage from the stem O-ring, so any seal failure can be noticed during inspection. Placing that hole on the side of the valve body allows fluid seeping past the stem packing to escape to the outside where it’s easily visible, rather than being trapped inside or hidden by other components. When the O-ring starts to fail, you’ll see a drip or dampness at that exterior hole, signaling maintenance is needed to replace the packing or O-ring before a bigger issue develops. Other locations wouldn’t give a reliable, observable warning path—inside a control panel or on top of the pump wouldn’t be readily visible, and the rim of the service tank isn’t aligned with the stem seal.