What type of flow does an orifice limit in a gas appliance?

In gas appliances, an orifice is used to regulate the flow of gas. This flow control is essential for maintaining the correct gas-to-air mixture needed for efficient combustion. The orifice creates a specific opening through which gas passes, effectively controlling the volume and pressure of the gas flow that reaches the burner.

When the orifice is designed for gas flow, it ensures that the appliance operates safely and efficiently by limiting the amount of gas that can go through at any given time. This regulation prevents excessive gas flow, which could lead to incomplete combustion, inefficient fuel usage, or even hazardous conditions.

While the other options mention various types of flows such as exhaust, fuel, and air, the orifice specifically pertains to the management of gas flow, making it a critical component in the operation of gas appliances. The proper functioning of an orifice is crucial in ensuring that the right amount of gas is supplied to the burner, in accordance with the design specifications of the appliance.