4.1 The eleven designations and where each truck may go

1 Eleven designations

1910.178(b) is explicit: for the purpose of the standard there are eleven different designations of industrial trucks or tractors — D, DS, DY, E, ES, EE, EX, G, GS, LP and LPS. Read as a family, the pattern is easy: the base letter is the power source, and additional letters mean additional safeguards.

EX is the outlier and the one worth remembering by name: it is the only designation the standard allows in several atmospheres where every other truck is prohibited.

2 Classify the location first

1910.178(b)(12) sets the order of operations, and it is the opposite of how most sites think about it: the atmosphere or location shall have been classified as to whether it is hazardous or nonhazardous prior to the consideration of industrial trucks being used there, and the type of truck required shall be as provided in the standard for that location.

In other words, nobody starts from the truck. Somebody classifies the room, and the classification produces the list of trucks allowed in it. That classification is your employer's responsibility, and 1910.178(l)(3)(ii)(F) makes hazardous (classified) locations where the vehicle will be operated a required training topic — which means you are entitled to be told which areas on your site are classified and what may enter them.

3 Where no truck may go

1910.178(c)(2)(i) contains an absolute prohibition, and it is worth reading as written. Power-operated industrial trucks shall not be used in atmospheres containing hazardous concentrations of acetylene, butadiene, ethylene oxide, hydrogen — or gases or vapors equivalent in hazard to hydrogen, such as manufactured gas — propylene oxide, acetaldehyde, cyclopropane, diethyl ether, ethylene, isoprene, or unsymmetrical dimethyl hydrazine.

No designation is excepted there. Not EX, not DY. If a hazardous concentration of any of those is present, the answer is that the truck stays out.

1910.178(c)(2)(ii) then handles dusts: trucks shall not be used in atmospheres containing hazardous concentrations of metal dust — including aluminum, magnesium and their commercial alloys, and other metals of similarly hazardous characteristics — or in atmospheres containing carbon black, coal or coke dust, except approved trucks designated as EX. And 1910.178(c)(2)(iii) provides that only approved trucks designated EX may be used in atmospheres containing acetone, acrylonitrile, alcohol, ammonia, benzine, benzol, butane, ethylene dichloride, gasoline, hexane, lacquer solvent vapors, naphtha, natural gas, propane and similar vapors.

4 Choosing between power types

Outside classified locations, the choice between electric, LP, diesel and gasoline is driven by ventilation, duty cycle and the surface. The safety consequences are what matter here.

One conversion rule sits here rather than in the fuel chapter. 1910.178(q)(12) allows industrial trucks originally approved for the use of gasoline to be converted to liquefied petroleum gas fuel, provided the complete conversion results in a truck that embodies the features specified for LP or LPS designated trucks — and requires that the conversion equipment be approved. A conversion is not a bolt-on decision made in the shop.

5 Ventilation, temperature and the truck's own condition

Two housekeeping paragraphs in (q) belong to this chapter because they are about ignition sources on the truck itself. 1910.178(q)(9): when the temperature of any part of any truck is found to be in excess of its normal operating temperature, creating a hazardous condition, the vehicle shall be removed from service and not returned until the cause has been eliminated or corrected. 1910.178(q)(10): industrial trucks shall be kept in a clean condition, free of lint, excess oil and grease, and noncombustible agents should be used for cleaning.

1910.178(q)(8) adds a rule specific to engine trucks with water mufflers: they shall be filled daily, or as often as necessary to keep the water above 75 percent of filled capacity, and any vehicle that emits hazardous sparks or flames from the exhaust system shall immediately be removed from service and not returned until the cause has been eliminated.

The theme across all three is that a truck's fire-safety designation describes the machine as designed and maintained. A GS unit caked in lint with a hot exhaust is no longer the machine that was approved.

6 What to do when you are not sure

This is the one chapter of the course where the correct operator response to uncertainty is not "be careful" but "stop and ask." Classification is a documented determination made by your employer, not something an operator can infer from a smell or a sign on a door.

1. 1
   Know your truck's designation. It is on the data plate. Photograph it, as Part 1 suggested.
2. 2
   Know which areas on your site are classified, and what may enter each. This is required training content under (l)(3)(ii)(F).
3. 3
   Treat an unclassified answer as a stop. 1910.178(b)(12) requires classification before the truck is even considered.
4. 4
   Report changes. A new process, a new chemical or a new storage area can change a classification, and (l)(4)(ii)(E) makes a change in workplace conditions a refresher training trigger.