Hail Impact Tester

M Global (Factory Mutual Research) “Approval Standard for Class I Roof Covers, Class Number 4470" includes a test “designed to assess the potential for damage to roof covers when adhered or attached directly to insulation, lightweight concrete roof decks, gypsum decks or FR-treated wood roof decks. It was developed to determine the potential for puncture of the roof cover resulting from hail storms when the cover is applied over its tested substrate insulation within a Class I assembly.” This is a laboratory test, but Canon Fabrications had the need to take the test to the field in a hail investigation. For a roof covering to be FM Approved it must meet the requirements for either: Moderate Hail Resistance (Class 1-MH), Severe Hail Resistance (Class 1-SH), or Very Severe Hail Resistance (Class 1-VSH).

To meet the requirements of Class 1-MH, a 2.0" diameter hardened steel “Canon Ball©” that weighs 1.19 pounds is dropped 6.75' yielding 8.0 ft-lbs of energy over the impact area of a 2" diameter ball.

To meet the requirements of a Class-1 SH, the same steel ball is dropped 11.79' yielding 14.0 ft-lbs of energy over the impact area of the 2" diameter ball. To emulate this in the field (and avoid setting up a 12' high drop tube), we drop a 2.0" diameter “Canon 5.0 lb. Missile©” 2.80'. This also yields 14.0 ft-lbs energy over the impact area of the 2" diameter missile. (When the same “missile” is dropped 4.40' it simulates ASTM D3746 delivering 22.0 ft-lbs energy.)

Finally, we offer a “Canon 10.0 lb. Missile©”. When this is dropped 5.30', it simulates the requirements of FM Class-1 VSH (Very Severe Hail) delivering 53.0 ft-lbs. energy. (When dropped 4.74' it simulates the requirements of UL 2218Class 4 yielding 23.71 ft-lbs.)

The Canon Hail Impact Tester© (HIT) is a used both in the field and in the laboratory to simulate the energy of hail stones impacting the roof. The HIT is available with options to run the FM Moderate, Severe, or Very Severe and ASTM hail tests.

  • Option 1 includes a high quality tripod and attachment fixtures (stored and shipped in an Alvin rugged plastic tube) to quickly and effectively plumb the device and assure the full energy of the impact ball or missile is delivered to the target.

    Pressure relief holes are drilled along the tubes and slots are cut in the bottom of the tube to prevent air back-pressure that could reduce the velocity of the ball in flight. The HIT has an integral two-way level to assure the tube is plumb in both axes.

    This option includes all needed to run the FM Moderate and FM Severe hail tests including two 2” Canon Balls© and a 5.0 lb. Canon Missile©. All of the components come in an all-weather hard shipping case with wheels.

  • Option 2 has everything in Option 1 plus a special “Canon ASTM Adapter Tube©” that allows dropping the 5 lb. Canon Missile© 4.40 ft. delivering 22.0 ft-lbs energy over the impact area of the 2” face of the missile.

  • Option 3 has everything in Option 2 and also includes a ”Canon 10# Missile” © and a “Canon FM Very Severe Hail Adapter Tube” © that allows dropping the 10 pound Canon Missile 5.30 ft. delivering 53.0 ft-lbs energy over the impact area of the 2” face of the missile. Use this 10.0 lb missile to simulate the FM Very Severe Hail Test without an ice missile launcher.

All of these are great for preliminary and field testing. Guidelines are included with the devices.

Canon Fabrications is constantly exploring other ways to assist in providing equipment and tools to enhance quality assurance and investigations of the building envelope. What do you need?