NFPA_460_-_Chapters_27-29_-_Foam_Proportioning_System_Performance_Testing.pdf

Aircraft Rescue and Firefighting Vehicle Foam Production

Performance Testing (NFPA 412)

27.1 Administrative

27.1.1 Scope.

Chapters 27 through 29 establish test procedures for evaluating the foam firefighting equipment installed on aircraft rescue and firefighting vehicles designed in accordance with Chapters 1 through 6 of NFPA 1900.

27.1.2 Purpose.

The tests specified in Chapters 27 through 29 provide procedures for the evaluation of foam firefighting equipment in the field to determine compliance with Chapters 1 through 6 of NFPA 1900 and this standard.

27.2 Foam System Performance Tests.

27.2.1 In addition to manufacturers’ performance testing, ARFF vehicles shall be tested on a schedule set by the AHJ to meet the following criteria:

(1) Expansion ratio

(2) Drainage 25 percent

(3) Proportioning https://link.nfpa.org/publications/460/2024/chapters/27 https://link.nfpa.org/publications/460/2024/chapters/29 https://link.nfpa.org/publications/460/2024/chapters/27 https://link.nfpa.org/publications/460/2024/chapters/29

Performance Criteria (NFPA 412)

28.1 Expansion Ratio and Drainage Time Requirements.

Foams shall be tested as specified in 29.3.2 and 29.3.3 of this standard and meet at least the performance requirements specified in Table 28.1.

Foam Agents Minimum Expansion

Ratio

Minimum Solution 25% Drainage Time (min)

Test Method A Test Method B

AFFF/FFFP/Fluorine-free air-aspirated

5:1 3 2.25

AFFF/FFFP/Fluorine-free non-air-aspirated

3:1 1 0.75

Protein 8:1 N/A 10

Fluoroprotein 6:1 N/A 10

28.1.1 The foam system shall be tested as specified in 29.3.2 and 29.3.3 of this standard and meet the performance requirements specified in Table 28.1.

28.2 Foam Solution Concentration.

28.2.1* For nominal 6 percent concentrates, the concentration shall be between 5.5 percent and 7.0 percent for turret and ground sweep nozzles and between 5.5 percent and 8.0 percent for hand line and undertruck nozzles.

28.2.2 For nominal 3 percent concentrates, the concentration shall be between 2.8 percent and 3.5 percent for turret and ground sweep nozzles and between 2.8 percent and 4.0 percent for hand line and undertruck nozzles.

28.2.3 For nominal 1 percent concentrates, the concentration shall be between 1.0 percent and 1.3 percent for all nozzles.

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Test Methods and Calculations (NFPA 412)

29.1 Preparation for Testing.

ARFF vehicles shall be inspected by a qualified technician familiar with the vehicle’s extinguishment systems prior to conducting a foam test.

29.1.1 This pre-test inspection shall ensure that the vehicle’s water and foam components are functioning as designed.

29.1.2 Items for inspection shall include the following:

(1) Verify water discharge rates of each device (−0 +10%) are in accordance with Chapters 4 through 6 of NFPA 1900.

(2) Verify vehicle pump operating pressure is in accordance with the OEM recommendations.

(3) Verify pressure relief valve settings are in accordance with the OEM recommendations.

(4)* Inspect the foam tank of each vehicle for the presence of crystallization, gelling, or sediment.

(5)* For output-based testing, obtain a sample of foam concentrate from the vehicle concentrate tank to form the baseline for concentration analysis and to determine whether the agent concentrate in the vehicle has been contaminated.

(6) Flush the piping system.

(7) If so equipped, inspect the eductor for any blockage.

(8) Inspect the foam metering device.

(9) Inspect water and foam electric or pneumatic components for correct operation.

(10) Inspect the manual foam metering valve or override for correct positioning.

29.2 Foam Solution Concentration Determination.

29.2.1* Foam solution concentration shall be determined using one of the following methods as described in 29.2.2, 29.2.3, or 29.2.4.

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29.2.1.1 All equipment used to determine percent concentrate shall be calibrated per the manufacturer’s recommendation.

29.2.1.2 When testing foam concentration from vehicles, the lowest flow rate outlet shall be tested first.

29.2.1.3 One calibrated handheld refractometer or one calibrated handheld conductivity meter suitable for the foam solution being tested shall be used for the methods described in 29.2.2 or 29.2.3.

29.2.1.4 The testing device shall meet the following minimum performance requirements:

(1) Visual refractometer, as follows:

(a) Range: 0.0 to 10.0 Brix

(b) Resolution: 0.01% Brix

(c) Precision: +/−0.1% Brix

(d) Temperature compensation range: 10°C to 30°C (50°F to 86°F)

(2) Digital refractometer, as follows:

(a) Range: 0.0 to 60.0 Brix

(b) Resolution: 0.1 Brix

(c) Precision: +/−0.1 Brix

(d) Temperature compensation range: 0°C to 50°C (32°F to 122°F)

(3) Conductivity meter, as follows:

(a) Range: 0.00 μS to 199.9 mS

(b) Resolution: 0.01 μS to 0.1 mS

(c) Accuracy: +/−1% FS

(d) Temperature accuracy: +/−0.5°C (0.9°F) https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000650 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000667

29.2.2* Method A (Output-Based Testing Using a Refractometer or Conductivity Meter).

A calibration curve shall be prepared using the apparatus and procedure in 29.2.2.1 and 29.2.2.2.

29.2.2.1 Apparatus.

In preparing the calibration curve, the following apparatus shall be used:

(1) Three 3.381 fl oz (100 mL) graduates

(2) One measuring pipette [0.338 fl oz (10 mL capacity)]

(3) One 3.381 fl oz (100 mL) beaker

(4) One 16.907 fl oz (500 mL) beaker

29.2.2.2 Procedure.

29.2.2.2.1* Using a “zero” reading or simply a sample of the water being used and foam concentrate from the tanks of the vehicle to be tested, the following three standard solutions shall be made up by pipe fitting into three beakers, each roughly 3.381 fl oz (100 mL) in size:

(1) The nominal concentration of the foam concentrate to water in height

(2) One-third more than the nominal concentration of the foam concentrate to water in height

(3) One-third less than the nominal concentration of the foam concentrate to water in height

29.2.2.2.2* The graduated cylinders shall then be filled to the 3.381 fl oz (100 mL) mark with water.

29.2.2.2.2.1 After thoroughly mixing, a refractive index or conductivity reading shall be taken of each standard solution.

29.2.2.2.2.2 A plot shall be made of the scale reading against the known foam solution concentrates and serve as a calibration curve for this particular series of foam tests.

29.2.2.3* Test Sample Concentration.

29.2.2.3.1 Portions of solution drained during the drainage test described in 29.3.2.2 shall be used as a source of test sample for the concentration determination.

29.2.2.3.2 https://link.nfpa.org/publications/460/2024/annexes/A/groups/29#ID004600000865 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000651 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000656 https://link.nfpa.org/publications/460/2024/annexes/A/groups/29#ID004600001236 https://link.nfpa.org/publications/460/2024/annexes/A/groups/29#ID004600000870 https://link.nfpa.org/publications/460/2024/annexes/A/groups/29#ID004600000873 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000714

Refractive index or conductivity readings of the test sample shall be compared to the calibration curve, and the corresponding foam solution concentration read from the graph.

29.2.3 Method B (Output-Based Testing Using a Refractometer Only).

A calculation shall be made using the apparatus and procedure described in 29.2.3.1 and 29.2.3.2.

29.2.3.1* Apparatus.

The concentration determination shall be made using the following apparatus:

(1) Three clean plastic or glass containers

(2) One dropper or pipette

(3) A refractometer with a scale capable of reading the complete refractive index for the samples

29.2.3.2 Procedure.

Using water and foam concentrate from the tanks of the vehicle to be tested, sample concentrations shall be determined as follows:

(1) Obtain a foam concentrate sample in a clean container and label “foam concentrate.”

(2) Obtain a water sample from the truck water tank or pump water discharge in a second clean container and label “water.”

(3) Allow foam solution to discharge from a hoseline or turret for at least 30 seconds. Obtain a foam solution sample from the discharge device in a third clean container and label “foam solution.” The portions of drained solution obtained during the drainage test described in

29.3.3.2 can be used for the “foam solution” sample.

(4) Take a refractive index reading for the water sample. Record the reading as Rw.

(5) Clean the instrument.

(6) Repeat step 29.2.3.2(4) with foam concentrate. Record the reading as Rc.

(7) Clean the instrument.

(8) Repeat step 29.2.3.2(4) with foam solution. Record the reading as Rs.

29.2.3.3 Test Sample Concentration.

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Determining the foam concentration of the foam solution sample shall be done by calculating the following formula using the readings obtained in the steps given in 29.2.3.2(4), 29.2.3.2(6), and 29.2.3.2(8):

[29.2.3.3]

29.2.4* Method C (Input-Based Testing).

A determination of the flow rates shall be made possible using the procedure and apparatus in

29.2.4.1 through 29.2.4.3.

29.2.4.1 Apparatus.

A device shall be used to measure the flow rate for the concentrate or the concentrate substitute.

29.2.4.1.1 A test sheet shall be compiled for each vehicle with measured water flow rates for each discharge, and the corresponding operational settings for the vehicle, as needed, in order to provide a known water flow rate from the water pump during each test.

29.2.4.1.2 A concentrate substitute shall be used instead of actual concentrate.

29.2.4.2 Procedure.

29.2.4.2.1 The foam concentration tank shall be closed off or the tank emptied and filled with substitute.

29.2.4.2.1.1 An alternative substitute shall flow in such a manner that the flow rates for the concentrate substitute can be read during testing.

29.2.4.2.2 Using the vehicle’s operational settings for producing foam, the operator shall test each discharge once flow rates have stabilized.

29.2.4.2.3 The flow rates for each discharge shall then be noted, together with any operational readings that could impact the water flow rates, such as water flow, concentrate flow, water pressure, or rpm.

29.2.4.2.4 After completing the testing, the concentrate supply pipes, piping, and tank shall be drained for any concentrate substitute in order to prevent dilution of the concentrate in the concentrate tank.

29.2.4.3 Concentration.

The foam solution concentrate shall be determined using this formula:

[29.2.4.3] https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000678 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000680 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000680 https://link.nfpa.org/publications/460/2024/annexes/A/groups/29#ID004600000875 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000684 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000684 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000693

29.3 Foam Expansion and Drainage Determination.

29.3.1 General Requirements.

29.3.1.1 Tests shall be conducted with the temperature of the water or foam solution in the range of 60°F to

80°F (16°C to 27°C).

29.3.1.2 The following corrections shall be applied to protective foams:

(1) Expansion ratio. If the solution temperature is higher than 70°F (21°C), no correction applies. If the temperature is lower than 70°F (21°C), add 0.1 unit of expansion for each 3°F (1.7°C) below 70°F (21°C).

(2) Drainage time. If the solution temperature is higher than 70°F (21°C), add 0.1 minute for each 3°F (1.7°C) above 70°F (21°C). If the solution temperature is lower than 70°F (21°C), subtract

0.1 minute for each 3°F (1.7°C) below 70°F (21°C).

29.3.1.3 Foam samples selected for analysis shall be representative of the foam produced by the nozzle as it would be applied to the fire hazard.

29.3.1.4 This selection shall be accomplished by placing a foam sample collector in the center of the ground pattern as determined in the nozzle pattern test.

29.3.1.5 Apparatus.

The expansion and drainage determinations shall be made using the following apparatus, in addition to the specific apparatus required for Method A or Method B:

(1) Stopwatch

(2) Scale/balance

(3) Straightedge

29.3.2 Test Method A.

29.3.2.1 Foam Sampling Apparatus.

29.3.2.1.1 The foam sample collector shall be constructed as specified in Figure 29.3.2.1.1.

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Figure 29.3.2.1.1 Foam Sample Collector, Method A.

29.3.2.1.2 The foam sample shall be collected in a standard 33.814 fl oz (1000 mL) capacity graduated cylinder.

29.3.2.1.2.1 The cylinder shall be cut off at the 33.814 fl oz (1000 mL) mark to ensure a fixed volume of foam as a sample.

29.3.2.1.2.2 The cylinder shall be marked in 0.338 fl oz (10 mL) graduations below the 3.381 fl oz (100 mL) mark.

29.3.2.2 Test Procedure.

29.3.2.2.1 The empty weight of the foam sample container shall be recorded to the nearest gram on a scale/balance having a maximum capacity sufficient to weigh the foam sample container and the foam sample.

29.3.2.2.1.1 The foam sample collector shall then be located in the center of the discharge pattern determined in Section 29.5.

29.3.2.2.1.2 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000767

The foam sample container shall be positioned at the bottom of the foam collector so that the foam hitting the collector flows into the container.

29.3.2.2.1.3 The foam nozzle shall flow for a minimum of 30 seconds prior to being aimed at the foam sample collector.

29.3.2.2.1.4 The foam nozzle shall be aimed so that the foam deflects off the side of the foam collector and then moved so as to discharge foam onto the foam sample collector.

29.3.2.2.1.5 As soon as the foam sample container has been completely filled with foam, the discharge nozzle shall be shut off and the timing of the 25 percent drainage started.

29.3.2.2.2 The foam sample container shall be removed from the base of the foam collector, excess foam struck off the top of the foam container using a straightedge, and any remaining foam wiped from the outside surface of the container.

29.3.2.2.3* The container shall then be placed on a level surface at a convenient height.

29.3.2.2.3.1 At 30-second intervals, the level of accumulated solution in the bottom of the cylinder shall be noted and recorded.

29.3.2.2.3.2 The drainage shall be recorded until the liquid level reaches 3.212 fl oz (95 mL) for non-aspirated nozzles, 2.029 fl oz (60 mL) for air-aspirated nozzles.

29.3.2.2.4 The container shall then be placed on the scale/balance.

29.3.2.2.4.1 The total weight of the foam sample and container shall be determined to the nearest gram.

29.3.2.2.4.2 The weight of the foam sample in the container shall be determined by subtracting the weight of the empty container from the weight of the container filled with the foam.

29.3.2.2.4.3 The weight of the foam sample in grams shall be divided by 4 to obtain the equivalent 25 percent drainage volume in fluid ounces (milliliters).

29.3.2.2.4.4 The 25 percent drainage time shall then be interpolated from the drainage data collected in

29.3.2.2.3.1 and 29.3.2.2.3.2.

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Samples of the foam shall be weighed to the nearest gram.

29.3.2.2.6 The expansion of the foam shall be calculated by the following equation:

[29.3.2.2.6]

29.3.3 Test Method B.

29.3.3.1 Foam Sampling Apparatus.

29.3.3.1.1 The object shall be to obtain a sample of foam that is typical of that to be applied to the burning fuel surface under anticipated fire conditions.

29.3.3.1.1.1 The foam collector shall be constructed as specified in Figure 29.3.3.1.1.1.

Figure 29.3.3.1.1.1 Foam Sample Collector, Method B.

29.3.3.1.2 The foam sample shall be collected in a cylindrical 54.102 fl oz (1600 mL) container.

29.3.3.1.2.1 The foam sample container shall be constructed as specified in Figure 29.3.3.1.2.1.

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Figure 29.3.3.1.2.1 54.102 fl oz (1600 mL) Foam Sample Container.

29.3.3.1.3 Foam drainage shall be recorded using a 3.381 fl oz (100 mL) graduated beaker for foams with expected expansion ratios above 5:1, and an 8.454 fl oz (250 mL) graduated cylinder for foams with expected expansion ratios of 5:1 or below.

29.3.3.1.4 The weight of the appropriate empty graduated cylinder shall be recorded before the test.

29.3.3.2 Test Procedure.

29.3.3.2.1 The empty weight of the foam sample container shall be recorded to the nearest gram on a scale/balance having a maximum capacity sufficient to weigh the foam sample container, on a suitable support, and the foam sample.

29.3.3.2.1.1 The foam sample collector shall then be located in the center of the discharge pattern determined in Section 29.5 of this standard.

29.3.3.2.1.2 https://link.nfpa.org/publications/460/2024/chapters/29#ID004600000767

The foam sample container shall be positioned at the bottom of the foam collector so that the foam hitting the collector will flow into the container.

29.3.3.2.1.3 The foam nozzle shall be aimed so that the foam deflects off the side of the foam collector, adjusted to its normal operating pressure, and then moved so as to discharge foam onto the foam sample collector.

29.3.3.2.1.4 As soon as the foam sample container has been completely filled with foam, the discharge nozzle shall be shut off and the timing of the 25 percent drainage started.

29.3.3.2.2 The foam sample container shall be removed from the base of the foam collector, excess foam struck off the top of the foam container using a straightedge, and any remaining foam wiped from the outside surface of the container.

29.3.3.2.2.1 The container shall then be placed on the scale/balance.

29.3.3.2.2.2 The total weight of the foam sample and container shall be determined to the nearest gram.

29.3.3.2.2.3 The weight of the foam sample in the container shall be determined by subtracting the weight of the empty container from the weight of the container filled with the foam.

29.3.3.2.2.4 The weight of the foam sample in grams shall be divided by 4 to obtain the equivalent 25 percent drainage volume in milliliters.

29.3.3.2.3 The foam sample container shall then be placed on a suitable support and a graduated cylinder placed below the drain spout.

29.3.3.2.3.1 At 30-second intervals as the foam breaks down, the accumulated foam solution in the bottom of the container shall be drawn off into a 3.381 fl oz (100mL) graduated cylinder and the amount recorded.

29.3.3.2.3.2 The drainage shall be recorded until the liquid level reaches 5.072 fl oz (150 mL) for non-aspirated nozzles, 3.212 fl oz (95 mL) for air-aspirated nozzles.

29.3.3.2.4 The foam sample container complete with any remaining foam shall then be weighed to the nearest gram.

29.3.3.2.4.1

The graduated cylinder used to record the drainage and the collected foam shall then be weighed in the same manner.

29.3.3.2.4.2 The net weight of the foam sample shall be determined by adding the weights in 29.3.3.2.4 and

29.3.3.2.4.1 together and subtracting the weight of the empty foam sample container and the empty graduated cylinder.

29.3.3.2.4.3 The net weight of the foam sample in grams shall be divided by 4 to obtain the equivalent 25 percent drainage volume in milliliters.

29.3.3.2.5* The expansion of the foam shall be calculated by the following equation:

[29.3.3.2.5]

29.4 Ground Sweep and Hand Line Nozzle Pattern Tests.

29.4.1 Ground sweep nozzles and hand line foam nozzles shall be discharged onto a paved surface for a period of 30 seconds, for pattern testing, as shown in Table 4.1.1.2 of NFPA 1900.

29.4.2 Ground sweep nozzles shall be discharged from their fixed positions.

29.4.3 Hand line nozzles shall be held at their normal working height and tilted upward to form a 30-degree angle with the horizontal.

29.4.4 Markers shall be set out to denote the outline of the effective foam pattern and plotted, as described for the turret test in 29.5.3.

29.4.5 Patterns from both the straight stream and the fully dispersed nozzle settings shall be established, measured, and recorded.

29.5 Turret Ground Pattern Test.

29.5.1 Pattern testing shall only be required for vehicle prototype testing by the vehicle manufacturer, as shown in Table 4.1.1.2 of NFPA 1900.

29.5.1.1 Prior to the start of the test, the following conditions shall be met:

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(1) The water tank shall be full.

(2) The foam concentrate tank shall be full with the type of foam concentrate to be used during actual emergencies.

(3) The proportioner shall be set for normal firefighting operation.

29.5.1.2 For premixed systems, the tank shall be full with the premixed solution in the correct proportion for normal firefighting operations.

29.5.2* Discharge tests shall be conducted to establish the firefighting foam discharge patterns produced and the maximum range attainable by the turret nozzle.

29.5.2.1 The test shall be conducted under wind conditions of 5 mph (8 km/h) or less.

29.5.2.2 To determine maximum discharge range, the turret nozzles shall be tilted upward to form a 30-degree angle with the horizontal.

29.5.3 Foam shall be discharged onto a paved surface for a period of 30 seconds at the specified pressure, in both the straight stream and fully dispersed nozzle settings.

29.5.3.1 Immediately after foam discharge has stopped, markers shall be placed around the outside perimeter to preserve the identity of the foam pattern as it fell on the ground.

29.5.3.2 For purposes of defining the edge of the pattern, any foam less than 1⁄2 in. (12.7 mm) in depth shall be disregarded.

29.5.3.3 Distances between markers shall be plotted on graph paper.

29.5.3.4 For each nozzle setting, the following shall be shown:

(1) The vertical axis shows the reach.

(2) The horizontal axis shows the pattern width.

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29.5.3.5 The distance from the nozzle to the end of the effective foam pattern shall be measured and plotted on the graph paper.