We thought we’d have some fun demonstrating a FOPS test and what better way than smashing granny’s ceramic garden mushroom. Come on – we know you’ve thought about it yourself!
In our final FOPS test we dropped a 45 kg (99.2 lbs) steel sphere from 3.1 meters (10 ft.-2 in. or 10.17 feet) on a ceramic mushroom. We wanted to simulate hand tools or bricks free falling onto the top of the FOPS which represents the ISO 3449 Level I – Test object.
Construction of building, bridges and other structures generally involves workers and equipment working and operating at different levels. In most cases these workers are oblivious to the actions of other coworkers and equipment. Small objects can be accidently dropped from higher levels onto areas where others are working. Level I FOPS are designed and tested to provide protection to those equipment operators that may be venerable.
We would. It may have seemed excessive dropping a 227 kg (500.45 lbs) steel cylinder from 5.22 meters (17 ft-1.5 in. or 17.13 feet) on a gazing ball but we had our reasons.
In this drop we wanted to demonstrate an ISO 3449 Level II – Test object –simulating a rock or tree limb free falling onto the top of the FOPS.
Construction, earth-moving and forestry equipment operators sometimes operate their equipment in areas where an object may roll down or fall onto the top of a FOPS from a higher level. The following photograph shows an example of this.
We dropped a 45.5 kg (100 lb) hardwood cube from 1.53 meters (5 feet) on a ceramic garden gnome and turned it to dust to illustrate an ANSI B56.6 – Cube drop object test. This test simulates a box or a light object free falling onto a forklift truck overhead guard.
Forklift trucks are also used to lift and place pallets that have stacked materials or boxes on the pallet. These materials or boxes may become unstable while being moved and may accidentally fall onto the top of the forklift truck’s operator’s compartment. The cube drop test simulates this condition and proves that the forklift truck’s overhead guard can withstand the energy these types of impacts unlike our little ceramic friend.
Why would we drop a bundle of lumber on a flock of flamingos? To demonstrate an ANSI B56.6 impact drop load test that would simulate a loaded pallet free falling onto a forklift truck overhead guard.
Operators of forklift trucks are vulnerable to falling objects (loads) that are being lifted. Sometimes these loads are not well secured or the load may shift while the forklift truck is moving to place the load at a level that is higher than the operator’s compartment. The impact drop load is proportionate to the lift capacity of the forklift truck’s lifting capacity. Per ANSI B56.6 specifications, the lightest impact load is 750 pounds while the heaviest is 3000 pounds.
While dropping a bundle of lumber on a flock of pink flamingos might be silly we take operator safety very seriously in our ISO/IEC 17025 accredited test lab. Our 1500 square foot, state-of-the-art, zero- degree OPS (Operator Protective Structure) test facility was erected for servicing off-highway equipment manufacturers in the agriculture, construction, sport utility, mining, forestry, and turf care industries. Various protective structures used with off-highway equipment can be tested to ANSI, ASABE, BS, ISO, MSHA, OECD, OSHA, SAE, CSA, and various company specific proprietary standards.
The answer can be found several ways depending on such factors as how much water was used, type of concrete, how long it was cured.
We came to our conclusion by consulting “Mark’s Standard Handbook for Mechanical Engineers.” Determining the force required for compressing concrete only (no drum) using the following table from page 6-188:
|Table II. Strength of Plain Concrete Cured at 28 Days
|Max water content, gal/bag of cement
|Compressive strength, lb/in2
We learned the ratio of water to concrete mix affects the cure, so we calculated two different ratios. Then we calculated the volume of the drum measuring 22” in diameter for a value of 397.61 square inches. The results:
Concrete mixed @ 5.0 gallons of water per bag
397.61 in2 x 4000 lb/in2 = 1,590,440 lbs of force
Concrete mixed @ 7.0 gallons of water per bag
397.6/1in2 x 2650 lb/in2 = 1,053,666 lbs of force
While we have reached the million-pound testing milestone in our lab, we won’t be taking on this close to 1.6 million-pound test. Watching this test would be about as exciting as watching the cement cure.
Custom Products of Litchfield’s second quarterly contest featured a full 16-gallon beer keg being smashed in our ISO/IEC 17025:2005 accredited ROPS test lab. Guesses of force were as little as 875 and as much as 485,000.
We wondered what calculations if any were involved in making those guesses. Jim Schmitt, Director of Engineering at Custom Products offered this example of how the amount of force could be calculated:
- If you know the size of the keg you can calculate the diameter in square inches.
- If you know the keg has a warning of “60 PSI max” you can multiply the diameter by the psi.
- Then multiplying that number by a predetermined safety factor, a term used to describe structural capacity beyond expected or actual loads might get you in the ball park.
“Similar predictions can be developed prior to ROPS testing,” said Schmitt. “Because we have conducted in excess of 750 destructive ROPS/FOPS evaluations we frequently have a benchmark observation prior to testing if the submitted specimen is a test worthy candidate.”
Custom Products of Litchfield’s first quarterly contest featuring a helmet being smashed in our ISO/IEC 17025:2005 accredited ROPS test lab was a smashing success. Guess submissions for the pounds of force used to smash the helmet went as high as 43,000 pounds with the closest winning guess of 888 pounds. The final weight of force to crush the helmet was 780 pounds.
We asked for ideas of what to smash next and the suggestions submitted were as far ranging as a bowling ball, a heavy duty vehicle jack and the winning idea of a beer keg. Visit SMASHit.info to submit your best guess by June 30, 2011 and if you’re closest, you’ll win.
How many pounds of force will it take to crush the 16 gallon keg like a can of your favorite beer?
SMASHit is an ongoing contest with two chances for you to win every quarter. Prizes include iPods, Kindle reader, a pair of Red Wing Boots, $300 in Snap-On Tools and other great gear.
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