Tanker: Tank Emergency Systems
5 questions in the bank cover this topic. Everything below is drawn from the sources those questions cite.
Sources: 49 CFR 177.840
What you need to know
177.840 puts closure and shutting down motive and auxiliary power first, in that one action.
Everything else happens after the flow stops and the ignition sources are off.
If there is an unintentional release of product to the environment during unloading of a liquefied compressed gas, the qualified person unloading the cargo tank motor vehicle must promptly shut the internal self-closing stop valve or other primary means of closure and shut down all motive and auxiliary power equipment.
49 CFR 177.840
177.840(o) sets 18 hours before the first delivery of the day, not per delivery and not per week.
A remote shut-off nobody has tested is a shut-off you only discover is broken when you need it.
an operator must successfully test the activation device within 18 hours prior to the first delivery of each day
49 CFR 177.840
The test proves the transmitter reaches from the distance you would actually be using it, which is why the rule sets a minimum and not a maximum.
the person conducting the test must be at least 45.72 m (150 feet) from the cargo tank and may have the cargo tank in his line of sight
49 CFR 177.840
The smaller tanks carry both limits plus a five-minute observation interval.
The point of the hose distance is that the hose is where a release starts.
the qualified person attending the unloading operation must remain within 45.72 meters (150 feet) of the cargo tank and 7.62 meters (25 feet) of the delivery hose
49 CFR 177.840
Where the rule imposes arm's reach, the mechanical closure has to be reachable without moving, because the seconds spent walking to it are the whole hazard.
The qualified person monitoring unloading must remain within arm's reach of the mechanical means of closure for the internal self-closing stop valve
49 CFR 177.840
Check yourself
- A liquefied compressed gas starts escaping while you unload. What comes first?
- How recently must your off-truck remote shut-off have been tested?
- Where must you stand to test a wireless remote shut-off?
- What two distances bind you while the self-closing stop valve is open?
- What does arm's reach of the means of closure apply to?
Answers are in the practice test for this topic.