Dammit satan you had one job
Not all fire alarms alert the fire dept. In a fire situation, a call should also always be made to 911 from a safe location. When they do alert the fire dept., it usually takes place by calling out on a phone line and reporting to a monitoring service, just as livysmom27 described very accurately.
LOL You must have had a real scare. These units must be serviced regularly. Low batteries are a real factor is setting the warnings off. This is not a nuisance, but a protection. Gasses like methane and carbon-monoxide, lighter than air or oxygen could accumulate. Once 2% volume is reached, the alarm should sound. At 5% people will immediately lose consciousness . Bad for you if there is a fire. I would rather have the warning. Always react when the alarm goes off.
A 1 3/4 Fire hose will NORMALLY have a 1 1/2 thread (though a 2 threaded fitting is made), so that will be one factor limiting the Actual FLOW RATE. When these are used they are almost always used with fire hose nozzles of one type or another. The discharge orifice size is significantly smaller than the 1 1/2 coupling ID, so it will further restrict the Actual FLOW RATE. The flow rate varies with the OUTLET Hose Pressure, which in turn varies from the Inlet Hose Pressure, by the pressure drop that occurs due to Friction in the hose and couplings through which the water passes. This Hose Pressure Drop is usually specified for a specific hose by the manufacturer as a Pressure Drop (Pressure Loss) per Hundred Feet (CFT). In order to get the necessary pressure at the nozzle to properly / safely operate, the pressure is adjusted at the pumpper truck based on the length of hose being used, and some other factors/ MUNICIPAL Fire Hose is Rated for a MAXIMUM Rated Working Pressure of 360 PSI, however this is far above the usual working pressure. Your Hose's Maufacturer should be able to narrow this down, based upon the hose and the outlet size. Contact them, with the Specifics of your application, Flow Rate you want, Pressure at the Outlet, etc.
