LIQUEFIED PETROLEUM GAS (LPG)

Liquefied petroleum gas (LPG), also called LPG or LP Gas, actually encompases 2 main gases - propane (C3) or butane (C4) are flammable mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles.


It is a clean-burning fossil fuel that can be used to power internal combustion engines. At normal temperature and pressure it is a gas but in a vessel under modest pressure it becomes a liquid. Varieties of LPG bought and sold include mixes that are primarily Propane or mixes that are primarily Butane. LPG evaporates at normal temperatures and pressures. LPG is heavier than air and thus tends to settle in low spots, such as basements. This can cause ignition or suffocation hazards if not dealt with.


LPG-fueled vehicles can produce significantly lower amounts of some harmful emissions and the greenhouse gas carbon dioxide (CO2). The international standard is EN 589. LPG is usually less expensive than gasoline, it can be used without degrading vehicle performance, and most LPG used in U.S. comes from domestic sources. In Australia, LPG (Propane) is virtually supplied to all homes and businesses.


LPG is supplied in gas bottles that are either exhanged or refilled on site by gas tankers. LPG (Butane) is supplied to specific businesses whereby it has advantage over Propane. These applications are normaly related to green house and use as propelent in aerosols. The chemcal formula for butane is C4H10. There is another mix -(Propane/Butane) called Autogas. This is the same LPG gas sold at petrol stations. Autogas LPG run vehicles and especially public bus and many private car owners have economic value as LPG cost is cheaper than petrol or diesel.


Another advantage is lower greenhouse gas emissions as compared with petrol or diesel. However the availability of LPG-fueled light-duty passenger vehicles is currently limited. A few light-duty vehicles—mostly larger trucks and vans—can be ordered from a dealer with a prep-ready engine package and converted to use propane. Existing conventional vehicles can also be converted for LPG use. Since propane is stored as a liquid in pressurized fuel tanks rated to 300 psi, LPG conversions consist of installing a separate fuel system if the vehicle will run on both conventional fuel and LPG or a replacement fuel system for LPG-only operation.



Advantages of LPG


More than 90% of propane used in U.S. comes from domestic sources. Delhi (India) public trasport bus service runs on LPG due to polution issue. In many countries now LPG driven public transport system is becoming mandatory. It is less expensive than gasoline. Low maintenance costs are one reason behind propane’s popularity for high-mileage vehicles.


Propane’s high octane and low-carbon and oil-contamination characteristics have resulted in greater engine life than conventional gasoline engines. It is Enviornmently friendly and reduces polution with potentially lower toxic, carbon dioxide (CO2), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions.


Disadvantages of LPG


There are still logistic issues. Limited availability (a few large trucks and vans can be special ordered from manufacturers; other vehicles can be converted by certified installers). It is lesser readily available than gasoline & diesel however new infrastructure is being mobilized.


It has fewer miles on a tank of fuel. Typically in fleet applications, propane costs less than gasoline and offers a comparable driving range to conventional fuel. Although it has a higher octane rating than gasoline rating (104 to 112 compared with 87 to 92 for gasoline), and potentially more horsepower, it has a lower Btu rating than gasoline, which results in lower fuel economy.


LPG SPECIFICATIONS - 50% Propane and 50% Butane mix

A. BUTANE
Typical Method Test Unit Design Actual ASTM
Ethane Mole % 0.08 G.C
Propane Mole % 0.95 2 Max G.C
Total C4 Mole % 98.3 97.5 Min G.C
Total C3 Mole % 0.75 0.82 Max G.C
SP-GR@60/60of To Be Reported D-
2598
Cu Corrosion 1Hr@100No.1 A Max D-
1838
Total Sulphur PPM 30 Max
H2S PPM Nil D-
H2S PPM Nil D-
2420
VP@100 PSIG 70 Max D-
2598
H2O Content PPM 10 Max Shaw
Dew Pt
Residue PPM 0.05 Max D-
2158
B. PROPANE
Typical Method Test Unit Design Actual ASTM
Erhane Mole % 0.47 Summer 0.4 Max
0.509 Winter
G.C
Propane Mole % 98.17 Summer 98 Min
98.17 Winter
G.C
Butane Mole % 1.353 Summer 1.4 max
1.249 Winter
G.C
Pentane & Heavier Mole % 0.01 Max G.C
SP-GR@60/60OE To Be Reported D-
2598
Cu Strip No.1 A Max D-
1838
Sulphur (Volatile) PPM 30 Max
Microcoulometry
H2S PPM 5 Max D-
2420
VP@100 PSIG 200 Max D-
2598
H2O Content PPM 10 Max D-
BUTANE PROPANE MIX SPECIFICATIONS
PROPANE-PROPYLENE…………………50%
BUTANE-BUTYLENES………………………50%
VAPOR………………………………………………………………………….37.8 MAX 1380 KA
SULFUR………………………………………………………………………..MAX 343 MG/M3
EVAPORATE WASTE MATERIAL…………………………. ………….MAX 100 ML
D Ci at h…………………………………………………………………………200,000

LPG SPECIFICATIONS - PROPANE TYPE


PROPERTY UNITS TEST METHOD VALUE
ETHANE MOL% G.C 0.4MAX
PROPANE MOL% G.C 98MIN
BUTANE MOL% G.C 1,4MAX
PENTANES & HEAVIER MOL% G.C 0.01MAX
COPPER CORROSION ----- ASTM D-1838 NO.1A MAX
HYDROGEN SULFIDE VOL.PPM ASTM D-2420/DRAGER 5MAX
SP.GR@(60F/60F) ----- ASTM D-2598 TO BE REPORTED
SULPHUR(VOLATILE) WT.PPM (BASED ON ASTM D-3246) 30MAX
VAPOR PRESSURE@(100 F) PSIG ASTM D-2598 200MAX
WATER CONTENT ----- ASTM D-2713 PASS

LPG SPECIFICATIONS - BUTANE TYPE


PROPERTY UNITS TEST METHOD VALUE
ETHANE MOL% G.C 0,08MAX
PROPANE MOL% G.C 2 MAX
TOTAL-C4 MOL% G.C 97.5MIN
TOTAL-C3 MOL% G.C 0,82MAX
SP.GR@(60OF/60OF ----- ASTM D-2598 TO BE REPORTED
COPPER CORROSION ----- ASTM D-1838 NO.1A MAX
TOTAL SULFIDE WT.PPM (BASED ON ASTM D-3246) 30MAX
HYDROGEN SULFIDE VOL.PPM ASTM D-2420/DRAGER NIL
VAPOR PRESS@(100 OF PSIG ASTM D-2598 70MAX
WATER CONTENT VOL.PPM SHAW DEW POINT 10 MAX
RESIDUE ON EVAPORATION VOL% ASTM D-2158 0,05MAX