Properties of Gas

What are the physical characteristics of different states of matter?

Liquid: definite volume and weight, no shape
Gas: definite weight, no volume or shape Solid: definite shape, volume, and weight

What influences the state of matter and what are the types of change?

Influenced by temperature and pressure
Physical change: easy to revert
Chemical change: difficult or impossible to revert

What is LNG and how is it stored?

Liquefied natural gas Stored at -161°C at 4 psig
Volume in liquid is 1/600th of gas volume Used for storage or transportation

What is LPG and how is it different from LNG?

Liquefied petroleum gas (group of hydrocarbons)
Exists as liquid/gas at low pressure and normal temperature
Natural gas not included (needs extreme temp or high pressure to liquefy)

What happens to boiling temperature as pressure increases?

Boiling point increases (more heat needed to boil)

What is vapor pressure and when does it stabilize?

Occurs as liquid boils and pressurizes vessel

Stabilizes when boiling stops at pressure equilibrium

What is the standard temperature and pressure?

0°C and 14.7 psia

What are the liquefaction ratios for propane and natural gas?

Propane: 270:1 ft³/ft³ (liquid), 43.6:1 ft³/gal (vapor)

Natural gas: 240:1 ft³/ft³ (liquid), 38.5:1 ft³/gal (vapor)

What is the BTU and how is it calculated?

BTU: heat to raise 1 lb of water by 1°F at STP

Formula: BTU = weight (lbs) × temp rise (°F) × specific heat (water = 1.0)

What are propane safety concerns and boiling point?

Mercaptan added for odour detection

Odour can fade due to water vapour or soil conditions

Boiling point = -44°F

What is the difference in specific gravity for matter?

Specific gravity differs if gas vs. liquid

What is a molecule and what are its classifications?

Smallest particle of a material

Mixture: atoms with no definite ratio

Compound: atoms in a fixed ratio

How many BTUs are needed to raise 83 lbs of water from 62°F to 184°F?

83 × (184 - 62) × 1.0 = 10,186 BTUs

How much gas is required to heat a 60 impgal tank from 35°F to 150°F at 80% of 25,000 BTU/hr?

Natural gas: 82.8 scfh

Propane: 33.12 scfh

What are ignition temperatures for propane and natural gas?

Propane: 950°F

Natural gas: 1200°F

Where is the hottest part of a flame?

Just above the tip of the inner blue cone

What are the flame temperatures of propane and natural gas?

Natural gas: 3350°F

Propane: 3500°F

What are the flammability limits (LEL/UEL) of propane and natural gas?

Propane: LEL 2.4%, UEL 9.5%

Natural gas: LEL 4%, UEL 15%

What does the presence of aldehydes in flue gas indicate?

Incomplete combustion

Likely CO present if aldehydes are detected

What is the flammability range of CO and its danger level?

CO flammable between 12% and 74% with air

4000 ppm lethal in < 1 hr

What do flame colors indicate about combustion contaminants?

Orange: dirt or dust

Green: refrigerant

Red: chemical contamination

What is the air-to-fuel ratio required for complete combustion?

Natural gas: 9.5:1

Propane: 23.5:1

Butane: 30:1

What are common impurities in fuel gas and their properties?

Benzene: colorless, flammable, sweet odour – crude oil, gasoline Xylene: colorless, flammable, solvent – petroleum, coal tar, forest fires

Ethylbenzene: colorless, flammable, gas smell – coal tar, petroleum Radon: colorless, odourless, radioactive – from uranium in rock/soil H₂S: colorless, rotten egg smell, poisonous – 100 ppm can be fatal Helium: recovered from natural gas Argon: inert, colorless, odourless, not very reactive