> Wet System
A wet fire protection system is a network of piping attached to a public or private water supply, containing a control valve, pressure gauge, alarm mechanism, drain, fire department connection, and alarm testing apparatus. The network of piping contains sprinkler heads spaced to accommodate the hazard per NFPA standards. Sizing of this piping can be pipe schedule, meaning so many sprinkler on a particular pipe size or hydraulically designed system where the limit of sprinklers is controlled by the available water supply volume and pressure. The way to establish pipe schedule system or calculated system is, a calculated system should have a hydraulic placard on riser. Also see Standpipe System for additional information.

Main Points to Establish

Main Control Valve
* Is the main control valve open and all valves down stream of the connection to the water supply open?
* Is this and all other valves controlling water to the system locked in the open position or supervised and functioning?

Pressure Gauges
* The pressure gauge should indicate that the system is filled with water pressure.

Alarm Mechanism
* There are two types of mechanisms, water flow switch and water motor gong.
* Are there wires connecting the water flow switch to bells or supervisory panel? Do alarms work when inspectors test is opened?
* A water motor gong will have a by-pass valve to allow the ringing of the bell.

Drain
* This valve allows the system to be drained and is used to test to see if the city water valve is open. This is done by opening the valve wide open while reviewing the pressure drop on the pressure gauge. The loss should not be significant. If it is the city water supply should be investigated.

Fire Department Connection
* This is used to allow the fire department to pump into, using their pumper truck to supplement the city water pressure. Threads should be checked to see if they meet standard threads used by local fire department.

Alarm Testing Apparatus
* This is usually a 1" located somewhere in the building and piped to the outside or a drain capable of sustaining a full 1" flow equivalent of one sprinkler orifice. When this valve is opened the alarm must ring.

Sprinklers
* There should be a supply of extra sprinklers in the facility as per NFPA #13 and a sprinkler wrench.
* As you walk through a facility there should be no gaps in coverage in those areas requiring sprinklers.
* The question should be asked if any area has been changed from one occupancy to another after original system had been installed.
* Are any sprinklers blocked or painted?
* What is the age of the sprinklers?

Certification of Inspection
* The owner, under NFPA #13A, is responsible for certain tests and the collection of certain data to demonstrate the performance capability of the system. The owner should have documentation of periodic testing and inspection.