A differential pressure metering apparatus comprising a manifold for fluidically coupling impulse lines for a differential pressure meter to measurement ports (50, 52) of a flow restrictor pipe section, the manifold comprising: a rigid body comprising a base for mounting to the flow restrictor pipe section, and an arm extending from the base to an impulse attachment portion for coupling to two impulse lines; a high pressure channel extending through the rigid body from a high pressure inlet port to a high pressure outlet T-junction in the impulse attachment portion, the high pressure outlet T-junction having opposing first and second high pressure outlet ports (70, 72) each defining an impulse line extension direction along which an impulse line extends when connected to the respective port; a low pressure channel extending through the rigid body from a low pressure inlet port to a low pressure outlet T-junction in the impulse attachment portion, the low pressure outlet T-junction I having opposing first and second low pressure outlet ports (74, 76) each defining an impulse line extension direction along which an impulse line extends when connected to the respective port; whereby the manifold is configured to be mounted to the flow restrictor pipe section in a wet-line configuration: when the longitudinal pipe axis of the flow restrictor pipe section extends horizontally; and when the longitudinal pipe axis of the flow restrictor pipe section extends vertically; wherein in the wet-line configuration, the first high pressure outlet port and the first low pressure outlet port define impulse line extension directions having a downward component, and the second high pressure outlet port and the second low pressure outlet port define impulse line extension directions having an upward component. a rigid body comprising a base for mounting to the flow restrictor pipe section, and an arm extending from the base to an impulse attachment portion for coupling to two impulse lines; a high pressure channel extending through the rigid body from a high pressure inlet port to a high pressure outlet T-junction in the impulse attachment portion, the high pressure outlet T-junction having opposing first and second high pressure outlet ports (70, 72) each defining an impulse line extension direction along which an impulse line extends when connected to the respective port; a low pressure channel extending through the rigid body from a low pressure inlet port to a low pressure outlet T-junction in the impulse attachment portion, the low pressure outlet T-junction I having opposing first and second low pressure outlet ports (74, 76) each defining an impulse line extension direction along which an impulse line extends when connected to the respective port; whereby the manifold is configured to be mounted to the flow restrictor pipe section in a wet-line configuration: when the longitudinal pipe axis of the flow restrictor pipe section extends horizontally; and when the longitudinal pipe axis of the flow restrictor pipe section extends vertically; when the longitudinal pipe axis of the flow restrictor pipe section extends horizontally; and when the longitudinal pipe axis of the flow restrictor pipe section extends vertically; wherein in the wet-line configuration, the first high pressure outlet port and the first low pressure outlet port define impulse line extension directions having a downward component, and the second high pressure outlet port and the second low pressure outlet port define impulse line extension directions having an upward component.