Mack MRU - LNG Fueling

OPERATION23
LNGTankPressureReliefValves
Periodicallypressurewillbeharmlesslyreleasedthroughtheprimaryreliefvalveas
thefuelheatsupandexpandsduetoambientoutsidetemperature.LiquidLNGin
thetankscanbeaslowas-260°F(-177°C).BecausesmallamountsofLNGare
convertedintolargeamountsofnaturalgas,pressuresmayrapidlyincreaseifameans
ofreliefisnotprovided.
Theprimaryandsecondarypressureventsarelocatedinsidethefueltankdoor.The
primaryventisconnectedtopipingwhichshouldbeattachedtothebodyofthe
truckfacingtowardtherearofthevehicle,awayfromthepassengercompartment.
Onlytheprimaryreliefvalveispipedaway.Thesecondaryreliefvalveshouldbe
leftwiththefactoryinstalledplasticcapinplace.Refertothetankmanufacturer’s
manualformoredetails.
Fromthefactory,theventpipingfromtheprimaryLNGtankventisattachedtothe
intakestackbydisposableplasticstraps.Thepipingshouldberemovedfromthe
intakestackandplumbedupandoverthebodybythebodyinstallersasshowninthe
illustrationattheendoftheSAFETYsectioninthishandbook.
CAUTION
Itisimportanttokeeptheprimarypressureventfreeofblockageduetoice,snow
ordebris.
LNGFueling
Normalprocedureistorefuelthetanksonadailybasisoreachtimethevehicleis
takenintoactiveservice.Thenormaloperatingpressureineachtankisapproximately
120psiorhigher.Ifthepressureislow,say90psi,thevehicleisprobablylowon
fuel.Asaresult,itwillbelowinpowerandmayeventuallyrunoutoffuel.
Note:CompleteandsafeinstructionsonLNGfuelingshouldbeobtainedfromthe
tankmanufacturer’smanualandfromtheassistanceofpersonnelwhoareexperienced
inLNGfueling.
WARNING
COVEREYESANDEXPOSEDSKIN.
Accidentalcontactwiththeeyesorskin
maycauseafreezinginjurysimilarto
aburn.Protecttheeyesandcoverthe
skinwheneverpossiblecontactwith
supercooledmetals,liquidsorgases
exists.