What 173.315N2 means in plain language
FMCSR 173.315N2 requires that hazardous materials tankers be equipped with emergency discharge controls beyond simple metered delivery systems. In other words, your tanker needs safety mechanisms that allow controlled, safe release of cargo in an emergency—not just the standard flow-control valve that meters normal operations.
This regulation exists because hazardous materials require multiple layers of protection. A metered delivery system is designed for routine loading and unloading. An emergency discharge control is a separate safety device that activates only when something goes wrong: a leak, a rupture, or an accident that could release dangerous cargo uncontrollably. Inspectors cite this violation when they find a tanker equipped only with a metered valve, with no additional emergency safeguard in place.
What our enforcement data actually shows
Across our 13 million+ inspection records, 173.315N2 has been cited only 1 time in total history. In the last 12 months, we recorded 1 citation. In the last 90 days, there were 0 citations. The vehicle cited was not placed out of service, resulting in a 0.0% out-of-service rate for this code.
This 0.0% OOS rate is significantly lower than the all-FMCSR average of 31.4%, which indicates that when this violation is observed, inspectors typically issue a warning or citation rather than removing the vehicle from service immediately. This code ranks #2796 out of 3,036 FMCSR codes by citation volume, making it extremely rare in roadside enforcement.
Who gets cited most
Our inspection records show that TRANSCAR JH LLC (USDOT 4309380) was cited once for this violation. With only 1 all-time citation nationally, geographic and carrier patterns are not statistically meaningful. If you operate a tanker carrying hazardous materials, this violation is not a widespread problem in your industry—it appears to be an isolated compliance gap rather than a systemic issue across fleets.
How severe is this compared to similar codes
Hazardous materials violations span a wide severity spectrum. Some peer codes in the same category show dramatically different enforcement patterns:
- 177.834A-HMC (General loading/unloading hazmat) has 3,954 citations with a 99.2% out-of-service rate—meaning inspectors almost always remove those vehicles immediately.
- 177.817(a) (Placarding violation) has 2,274 citations and a 75.1% OOS rate.
- 172.602(c)(1) (Maintenance/accessibility of Emergency Response information) has 1,464 citations but only a 0.0% OOS rate, matching 173.315N2.
The fact that 173.315N2 shares a 0.0% OOS rate with emergency response information violations suggests that inspectors view this as a correctable deficiency rather than an immediate safety emergency warranting roadside removal.
How to avoid it
If you operate a tanker for hazardous materials, take these steps before your next inspection:
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Verify your tanker's emergency discharge system during pre-trip. Walk the entire perimeter of your tank and locate the emergency discharge valve or control mechanism. Know where it is and confirm it moves freely and is not corroded or damaged. Do not rely solely on your metered delivery valve—confirm a separate emergency control exists.
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Request certification from your carrier or equipment provider. Ask for documentation that your specific tanker meets 173.315N2 requirements. If paperwork is missing or unclear, report it to your fleet safety manager before you roll.
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Inspect for deterioration on routine tank maintenance. Emergency discharge controls can rust, corrode, or become stuck from lack of use. If your carrier performs annual tank service, ensure the technician tests and documents the emergency control as part of that service.
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Understand your cargo type. Not all hazmat requires the same controls. If you're hauling corrosives, flammables, or gases, your tanker design must match the cargo class. Verify with your dispatcher that your assigned vehicle is certified for the load you're carrying.
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Flag any tanker with only a single valve system. If you notice a tank that appears to have no separate emergency discharge mechanism, do not accept that load. Report it to dispatch with a photo if possible. One citation exists in our entire dataset—do not let it be yours.