What does the movement of the 1/2 cubic foot test dial indicate if the manual shut-off valve is closed?

When the manual shut-off valve is closed, the movement of the 1/2 cubic foot test dial indicating a gas leak downstream from the gas meter is significant. This is because the test dial is designed to measure gas flow. If the valve is closed and there is movement on the dial, it suggests that gas is still escaping from the piping system downstream. This could occur due to a compromised or leaking connection, a fault in the appliance, or damage to the piping leading away from the meter.

A normal operation would mean the dial remains stationary when the valve is closed, as no gas should flow. Likewise, pressure fluctuations would not cause the dial to move when the system is at rest and closed off unless there is an external influence not mentioned in this scenario. A measuring error would imply that the test dial gave an inaccurate reading for another reason, which can be ruled out by confirming the system is isolated with the shut-off valve closed. Therefore, movement of the test dial under these conditions strongly indicates the presence of a leak in the downstream system.