Foam test system for firefighting vehicle

1. A method of testing the accuracy of a firefighting vehicle's foam system, the method comprising:

(a) operating a pressurized foam addition system comprising a continuous flow loop including a pump and a mixing device in a normal mode, including:

(i) supplying a foam concentrate stream through a foam metering device to the flow loop at the mixing device;

(ii) supplying a first tank water stream from a water tank on the vehicle to the flow loop between the mixing device and the pump; and

(iii) mixing the foam concentrate stream and the first tank water stream to form a foam-and-water mixture by continuously circulating the foam-and-water mixture along the flow loop such that the continuously circulated foam-and-water mixture leaves the mixing device, passes through the pump, and reenters the mixing device;

(b) operating the foam addition system in a test mode, including:

(i) supplying a test water stream from the water tank through the foam metering device to the flow loop at the mixing device;

(ii) supplying a second tank water stream from the water tank to the flow loop between the mixing device and the pump; and

(iii) mixing the test water stream with the second tank water stream to form a test water/tank water mixture by continuously circulating the test water/tank water mixture along the flow loop such that the continuously circulated test water/tank water mixture leaves the mixing device, passes through the pump, and reenters the mixing, device; and

(c) during at least a portion of step (b), measuring the amount of the test water stream flowing through the foam metering device.

2. The method according to claim 1 , wherein step (c) includes measuring the flow rate and/or total flow of the test water stream flowing through the foam metering device.

3. The method according to claim 1 , wherein the first and second tank water streams do not flow through the foam metering device during steps (a) and (b).

4. The method according to claim 1 , wherein step (b) includes discharging the test water/tank water mixture from a discharge outlet.

5. The method according to claim 4 , further comprising measuring the amount of the test water/tank water mixture discharged from the discharge outlet, wherein the measuring of the amount of the test water/tank water mixture includes measuring the flow rate and/or total flow of the test water/tank water mixture discharged from the discharge outlet.

6. The method according to claim 5 , further comprising determining a concentration of the test water stream in the test water/tank water mixture using the measured amount of the test water/tank water mixture discharged from the discharge outlet and the measured amount of the test water stream flowing through the foam metering device.

7. The method according to claim 1 , further comprising using a flow control system to shift from the normal mode to the test mode, wherein the flow control system comprises a foam concentrate valve and a test water valve.

8. The method according to claim 7 , wherein during the test mode the test water valve is open so as to permit flow of the test water stream from the water tank into the foam metering device, wherein during the test mode the foam concentrate valve is closed so as to prevent flow of the foam concentrate stream from a foam tank into the foam metering device.

9. The method according to claim 1 , wherein the foam addition system comprises a flow meter for carrying out the measuring of step (c), wherein the flow meter is a magnetic flow meter.

10. The method according to claim 9 , wherein the flow meter is mounted on the firefighting vehicle.

11. The method according to claim 9 , wherein the flow meter is positioned upstream of the foam metering device.

12. The method according to claim 1 , wherein the foam addition system comprises an eductor, wherein during the normal mode the foam concentrate stream and the first tank water stream are mixed in the eductor, wherein during the test mode the test water stream and the second tank water stream are mixed in the eductor.

13. The method according to claim 1 , wherein the foam addition system is an around-the-pump system.

14. The method according to claim 1 , wherein the foam concentrate stream comprises an aqueous film forming foam (AFFF).

15. The method according to claim 1 , wherein the foam concentrate stream comprises an ether in an amount of at least 1 percent by weight and not more than 20 percent by weight.

16. A method of testing the accuracy of a firefighting vehicle's foam system by operating a pressurized foam addition system comprising a continuous flow loop including a pump and a mixing device in a test mode, the method comprising:

supplying a test water stream from a water tank on the vehicle through a foam metering device to the flow loop at the mixing device, wherein the foam metering device is configured, during a normal mode, to meter a foam concentrate stream supplied from a foam tank to the flow loop, and wherein the flow loop is configured, during the normal mode, to mix the foam concentrate stream and a first tank water stream supplied from the water tank to the flow loop to form a foam-and-water mixture by continuously circulating the foam-and-water mixture along the flow loop such that the continuously circulated foam-and-water mixture leaves the mixing device, passes through the pump, and reenters the mixing device;

measuring the amount of the test water stream flowing through the foam metering device;

supplying a second tank water stream from the water tank to the flow loop between the mixing device and the pump;

mixing the test water stream with the second tank water stream to form a test water/tank water mixture by continuously circulating the test water/tank water mixture along the flow loop such that the continuously circulated test water/tank water mixture leaves the mixing device, passes through the pump, and reenters the mixing device;

discharging the test water/tank water mixture from a discharge outlet; and

measuring the amount of the test water/tank water mixture discharged from the discharge outlet.

17. The method according to claim 16 , wherein the second tank water stream does not flow through the foam metering device.

18. The method according to claim 16 , further comprising determining a concentration of the test water stream in the test water/tank water mixture using the measured amount of the test water/tank water mixture discharged from the discharge outlet and the measured amount of the test water stream flowing through the foam metering device.

19. The method according to claim 16 , wherein the firefighting vehicle includes a flow control system configured to shift from the normal mode to the test mode, wherein the flow control system comprises a foam concentrate valve and a test water valve, and wherein the method further comprises:

opening the test water valve so as to permit flow of the test water stream from the water tank into the foam metering device; and

closing the foam concentrate valve so as to prevent flow of the foam concentrate stream from the foam tank into the foam metering device.

20. The method according to claim 16 wherein the firefighting vehicle includes an eductor, the method further comprising mixing the test water stream and the second tank water stream in the eductor.