MC-306 (DOT 406)
Non (low) Pressure Bulk Liquid Cargo Tank
- MC 36 – Maximum operating pressure of up to 3 psi
- DOT 406 – Maximum operating pressure of up to 4 psi
- Oval or egg-shaped cross-section
- Flat or nearly flat ends
- Aluminum – primary material of construction
- Usually multi-compartmented
- Separate manhole for each compartment
- Emergency shutoff-drivers side front
- Rollover protection to prevent manholes from opening up on rollover
- Average maximum capacity – 9,000 gallons
Contents:
- Normally – Petroleum products, however, may be water or milk
MC-307 (DOT 407)
Low-pressure Bulk Liquid Cargo Tank
- DOT 407 – Pressure – up to 40 psi @70°F
- Horseshoe-shaped cross-section
- Flat or slightly rounded ends
- Stainless steel is primary material of construction
- May be insulated. Insulation may hide tank shape – may not appear to be horseshoe-shaped
- Manway usually center (top) of tank
- Discharge valves usually center (bottom) of tank
- If multi-compartmented, will have a separate manhole for each compartment
- Emergency shutoff – drivers side front
- Rollover protection to prevent manholes from opening up on rollover, normally center of tank top
- Average maximum capacity – 6,000 gallons
Contents:
- Normally – mild acids, however, water, milk or combustible liquids
MC-312 (DOT 412)
Corrosive Cargo Tank
- DOT 412 – Pressure -5 to 25 psi Exterior strengthening (stiffer) rings often visible
- Lined tank – usually lined with rubber or plastic
- Round cross-section
- Stainless steel is primary material of construction
- May be insulated, insulation may hide tank shape
- Manway usually rear (top) of tank
- Discharge valves usually rear (bottom) of tank
- If multi-compartmented, will have a separate manhole for each compartment
- Emergency shutoff – drivers side front
- Cigar shaped tank – long, small in diameter
- Average maximum capacity – 4,000 to 6,000 gallons
Contents:
- Corrosives
- High weight (specific gravity) liquids
MC-331
Gases that are liquefied by pressure application only
- Circular cross-section
- Rounded ends
- Single shell carbon steel construction
- All valves, gauges, piping protected against damage from rollovers
- Painted white for reflecting suns UV light rays
- Pressure – 100 to 500 psi
- Gases that are liquefied by pressure application
- Capacity – from 2,500 gallons for bobtail to 11,500 gallons for highway transport truck
Contents:
- Propane (LPG)
- Butane
- Chlorine
- Anhydrous Ammonia
MC-338
Cryogenic Cargo Tank
- Cryogenic liquids (DOT definition of cryogenic states that substance must be at least -130°F)
- Cylindrical shaped with “box cabinet” on rear of tank, door for loading/unloading operations are usually within these doors
- Thermos bottle design; 2 cylinders, cylinder-within-a-cylinder
- Area between 2 cylinders evacuated of air (vacuum)
- It is normal to see vapors escaping from the vent “stack” on rear cabinet area of container
- Pressures from 23.5 to 500 psi – normally low pressure
Contents:
- Substances which con not be liquefied by pressure application alone, these substances must be (super cooled) to become a liquid
- Liquid oxygen, hydrogen, carbon dioxide
High-pressure Tube – Gasses that con not be liquefied with pressure application
- Each tube is a separated container
- Each tube is thermally protected with thermal plug that is designed to melt out under fire conditions to relieve internal pressure
- Tubes are individually controlled in rear compartment
- Off-loaded by “cascade style” (same method as used to fill SCBA bottles)
- Pressures of 4,000 to 6,000 psi per tube
- Usually 9 to 12 tubes per trailer
- High-pressure tube rail cars are of the same design as these styles of highway cargo tanks
Contents:
- Gases that can not be liquefied by only pressure application
- Helium, nitrogen, argon