Where must sensing lines for the fire pump and jockey pump tie into the system?

The sensing lines for the fire pump and jockey pump must tie into the system between the discharge check valve and the discharge control valve. This position is crucial because it ensures that the sensing lines can accurately measure the pressure within the system and respond accordingly during operation.

By placing the sensing lines in this position, any drop in pressure can trigger the jockey pump to operate and maintain the desired system pressure. Additionally, this setup prevents any potential backflow issues that could arise if the sensing lines were placed before the discharge control valve, which might not provide an accurate pressure reading due to the restrictions imposed downstream of the control valve. It also avoids potential isolation from the system if placed before the discharge check valve, which may not give a true reflection of the pressure conditions in the system when the pump is activated.