Following are basic steps recommended to commission a Hi Ex hangar foam system:

Inspect the system for proper installation of proportioning system components and generator mounting

 

Fill the foam tank following the manufacturer’s recommended procedures - normally done the day before the actual foam

          discharge test

 

Pretest the system with water discharge (close manual foam injection valve) through the generators and record riser water

           pressure and view discharge patterns from all generators. It is good to do this the day before the foam discharge test.

 

Inspect the foam solution inlet strainers for any signs of debris after the water discharge test

 

The contractor should hang plastic sheeting on the hangar walls to protect electrical devices in preparation for the foam

          discharge test. Normally plastic up to 10 feet on the walls is adequate.

 

Tape the aircraft fuselage outline on the hangar floor using masking tape or other suitable means.  This will aide in determining

          the 90% foam coverage at the one minute mark

 

Place some of the empty foam drums in the hangar bay to use as foam depth indicators during the foam discharge test. Drums

          are about 3 feet high so they make good depth indicators.

 

Mark the hangar walls at one meter height to aide in determining foam depth

 

Make a base curve of conductivity versus percent foam concentration using water from the fire system and foam from the tank.

          Refer to NFPA-11 or U.S.  Air Force/Air National Guard ETL specs for details if the job involves a military hangar. Sometimes

          a refractometer may be required instead of a conductivity meter.

 

Arrange for bleeding foam solution samples from each foam riser during the foam discharge test.  This can be done by small

           valves on the foam risers or possibly a garden hose connected to the wye strainer (if equipped) flush out point at the inlet of one

          of the foam generators.

 

Videotape the foam discharge test from start to finish so the actual test results can be reviewed in "real time"

 

Measure the conductivity of the foam solution test samples and compare the readings to the base curve to determine the percent

           foam injection rate.

 

Refill the foam tank following the foam discharge test.

 

Let the foam sit for 24 hours before attempting any clean up. By that time most of it will be gone and the remainder can be rinsed

           away with a garden hose on spray pattern.