What is the function of a Siamese manifold on a pumper?

• A. To measure water temperature
• B. To combine two water sources into one larger line for higher flow or to serve multiple attack lines
• C. To regulate engine speed
• D. To vent air from the pump

Answer: (B)

The main idea is that a Siamese manifold on a pumper is used to bring two water sources together into one larger path, which increases the flow available and gives you the flexibility to feed more than one attack line or a bigger main. In practice, two supply hoses or hydrant connections attach to the two inlets, and water flows through the manifold to a single, larger outlet. That setup lets you pull water from both sources at once, boosting total capacity, or it lets you drive a larger main that can then be split downstream to two attack lines as needed. It’s not used for measuring water temperature, regulating engine speed, or venting air from the pump, which are handled by other components.