When performing branch line hydraulic calculations, how is the fitting loss for straight-through flow in a tee or cross treated?

In branch line hydraulic calculations, the treatment of fitting loss due to straight-through flow in a tee or cross fitting is typically regarded as not included in the calculations. This is primarily because, for fittings such as tees and crosses, the flow does not experience a significant change in direction when moving straight through them.

In hydraulic calculations for sprinkler systems, it’s essential to account for friction loss due to the length of pipe and fittings, but when the flow proceeds in a straight line through a fitting, there typically isn't additional loss attributed to that fitting. The loss occurs primarily at points where the fluid direction changes, such as in bends or elbows. Hence, straight-through flow in a tee or cross does not contribute additional loss that would need to be captured in the calculations, simplifying the overall hydraulic calculations for the system.

Understanding this principle helps ensure that hydraulic calculations remain efficient and accurate, ultimately leading to effective design and operation of sprinkler systems.