Which gauge measures the steam pressure inside the boiler?

The steam pressure gauge is the instrument specifically designed to measure the steam pressure inside the boiler. This gauge provides critical information about the steam system's operational pressure, which is vital for safe and efficient boiler functioning. Maintaining the correct steam pressure is essential for ensuring that the boiler operates within its rated capacity and does not pose safety risks, such as explosions or structural failures.

In contrast, the oil pressure gauge indicates the pressure of the oil being supplied to the burner, which is unrelated to the steam pressure. The temperature gauge measures the temperature of the water or steam, providing insight into the thermal state of the system but not specifically measuring pressure. Lastly, the flow gauge measures the rate of fluid flow, which again does not pertain to the pressure within the boiler. Thus, the steam pressure gauge is the appropriate choice for measuring the steam pressure inside the boiler.