Safety
Features
Liquified
Natural Gas, like other fuels, needs to have built-in design features
to protect against a catastrophic failure which could impact employees
or the environment. NexGen Fueling equipment is equipped with alarm
systems, built-in safety features on critical items and emergency shutdown
features to address this issue.
Alarm
Systems
NexGen Fueling fuel stations include both methane and fire detection,
as well as emergency shutdown buttons. When the level of methane reaches
20% of the LEL (Lower Explosive Limit) a visible warning will appear.
If the level should reach 40% of the LEL, or a flame is detected, an
audible warning will sound and the station will shut down. The control
system can be programmed to automatically call the fire department when
either or both warnings are activated. The controls are located outside
of the fueling station containment area, to allow personnel to access
it without approaching the station equipment in case of emergency. Our
systems satisfy NFPA 59 A Chapter 10 and NFPA 57 requirements and NFPA
70 Design for UPS requirements.
Built-in
Safety Features
NexGen Fueling's cryogenic tanks are vacuum jacketed to minimize heat
leak into the cold liquid, which in turn minimizes the build up of pressure.
All tanks incorporate several means of controlling pressure, including
dual pressure relief devices and a manual vent valve. One set of relief
devices continues to operate while the other set is being serviced,
allowing the station to remain functional. Each branch of the circuit
has two relief devices, so if one fails in the "stuck open"
mode, the other is always available.
NexGen Fueling's bulk tanks
are made from 9% nickel alloy, which provides a strong, cold-resistant
metal that is very robust. All bulk tanks are of a dual wall construction,
similar to a thermos bottle, providing superior insulating qualities
as well as a strong and study vessel. NexGen Fueling's fueling stations
are designed to withstand Seismic Zone 4 conditions. A form of liquid
containment is incorporated into each station in case of major spills
of LNG during loading or offloading. The legs of the bulk tank are sprayed
with a special insulating coating that protects the legs in the event
of a fire, in accordance with NFPA 57.
Emergency
Shutdown Features
Fail-safe valves that isolate the storage tank in the event of an automatic
shutdown protect all main LNG connections. The valving for the fuel
station is air actuated with spring return. The airlines are designed
to melt when they get hot, such as in case of fire. When the airlines
melt, all of the air-actuated valves move to their "normally closed"
position, which stops all flow of liquid. NexGen Fueling's LNG dispenser
is equipped with a breakaway device that will break apart in case of
a driveaway. Once the device breaks, the air for the air-actuated valves
is automatically interrupted which in turn closes all of the air actuated
valves and stops all flow of liquid.
NFPA
57 & NFPA 59 Containment Area Issues
NFPA 57 and 59A Chapter 10 are the two guidelines for LNG and LCNG station
spill containment. NFPA 57 section 3-2.33 requires containment for a
10-minute worst case spill from offload equipment. Effectively this
becomes a 10,000 gallon spill that must be addressed by the station
design since there is no positive control over the design of the transport
and the training and reliability of the transport driver. The standard
site preparation includes an at grade foundation and containment by
means of a wall. Alternately, the site can be configured with the foundation
below grade and the offload area sloped to drain into the primary containment
area.
Codes
and Regulations Met
NFPA 57, NFPA 59A, NFPA 70, NFPA 72 Uniform Building Code, California
Title 8, ASME Sec. VIII div. 1, ANSI B31.3
