What does the exhaust primer do?

The exhaust primer functions by creating a vacuum using exhaust gases, which is essential for starting the priming process in fire apparatus. When activated, the primer utilizes the engine's exhaust to generate a low-pressure area in the suction line, effectively drawing water into the pump from a static source, like a hydrant or a water tank. This process is critical because it helps to remove air from the pump and its intake lines, facilitating a quick and efficient prime to start pumping operations. This ability to utilize exhaust gases makes the primer an important component in ensuring that firefighters can establish water flow without delay when responding to emergencies.