Load Classifications

By the nature of a linear drainage system it is subject to traffic of varying loads, speeds, and types.  The Dura Trench drain product line has been used in all types of load condition from occasional foot traffic to constant aircraft traffic.  The question arises at how to determine what system can be used for a particular application.  In order to make this determination there are several testing standards that may be referenced in order to determine the strength of a particular system.  The following standards are some of the most common standards used for linear drainage systems:

This standard is used when the trench drain system will be used inside of a building.  This is a plumbing standard developed by the American Society of Mechanical Engineers.  The test method uses a 3.5″ diameter test block to push on the drain.  The drain is then rated as light duty (<2000 lb), medium duty (2000 lb thru 4,999 lb), heavy duty (5000 lb thru 7499 lb),  extra heavy duty (7500 lb thru 10,000 lb), or special duty (>10,000 lb).  The load rating is given by taking the load at failure and dividing by 2 giving a 2x safety factor.

This standard is used for trench drains in civil and transportation work.  This standard was developed by the American Association of State Highway and Transportation Officials.  This standard was updated in 2010 to account for various sizes of linear drainage systems.  The test method typically uses a 9″ x 9″ test block to push on the grating with a force of 40,000 lbs.  For items where the test block would transfer load directly to the frame a modified test block is used.  The modified test block must be smaller than the frame opening and cannot be larger than 9″ in any direction.  The load shall be modified to 494 psi multiplied by the surface area of the grate, but not to exceed 40,000 lb for HS-20 or 50,000 lb for HS-25 loading.

This standard is used for trench drains in aviation work and sea ports.  This standard was developed by the Federal Aviation Administration.  This standard typically utilizes a 9″ x 9″ test block with a force of 100,000 lbs.  The test block size is not specifically called out in this standard, however, the 9″ x 9″ is referenced elsewhere and is the industry standard.

This trench drain standard is not an American standard, but it is used by many trench manufacturers.  This test standard is one of the few that was specifically written for trench drains.  This standard uses three different size test blocks.  The first is a 3″ wide x 10″ long for trenches 8″ wide or less.  A 6″ x 10″ test block is specified for trenches between 8″ and 12″.  For trenches wider than 12″ a 10″ diameter test block is used.  This standard classifies the loads in a alphanumeric format ranging from A through F.  Load class A is 15 kN (3372 lb), B is 125 kN (28,100 lb), C is 250 kN (56,200 lb), D is 400 kN (89,920 lb), E is 600 kN (134,800 lb) and F is 900 kN (202,320 lb).  Be sure that if a specification calls out a load class by a letter that it specifically states that the letter designation is a DIN classification.