Regulators and gas control valves are at the heart of gas pressure regulation. The regulators are designed to limit the pressure delivered to the gas control valves to a specified maximum, typically 1.7 kPa (7 inches water column gauge (w.c.)) for natural gas and 3.2 kPa (13 inches w.c.) for propane. The gas control valve allows gas to flow to its associated appliance burner when there is a call for operation. The gas control valve usually has internal regulation, which reduces the manifold pressure below that of the incoming pressure, typically about 0.87 kPa (3.5 inches w.c.) for natural gas and 2.5 kPa (10 inches w.c.) for propane.