G22 practice test

The primary environmental advantage of CNG over LPG is its lower carbon dioxide emissions. CNG produces about 20-30% less CO2 than LPG when burned. While both fuels have low particulate matter emissions and CNG may have slightly lower NOx emissions, the CO2 reduction is the most significant environmental benefit.

ISO 22991 is the international standard that specifies the requirements for the design, manufacture, and testing of LPG cylinders. This standard ensures that LPG cylinders meet safety and quality requirements for global use.

The lower explosive limit (LEL) of propane in air is approximately 2.1% by volume. This means that propane can form an explosive mixture with air when its concentration is at or above 2.1%. Understanding this limit is crucial for safe handling and ventilation requirements.

PVC (Polyvinyl Chloride) is not recommended for LPG piping systems due to its potential for degradation when exposed to LPG. Copper, steel, and polyethylene are commonly used materials for LPG piping, each with their own advantages and appropriate applications.

CNG typically contains 80-90% methane, with the remainder being made up of other hydrocarbons like ethane, propane, and butane, as well as small amounts of carbon dioxide and nitrogen. The exact composition can vary depending on the source of the natural gas.

CNG is not highly combustible in liquid form because it does not exist as a liquid under normal atmospheric conditions. It remains a gas even at very low temperatures. The other characteristics (lighter than air, colorless, and naturally odorless) are correct for CNG.

The general guideline for storing LPG cylinders is to keep them at least 3 meters away from ignition sources. This distance helps reduce the risk of accidental ignition in case of small leaks. However, specific regulations may vary by region and application.

Ethyl mercaptan is the most commonly used odorant for both LPG and CNG. It's added to these naturally odorless gases to give them a distinctive smell, allowing for easier detection of leaks by human olfactory senses.

A catalytic converter is not part of an LPG cylinder valve assembly. It's a component found in vehicle exhaust systems. The other components listed (pressure relief valve, excess flow valve, and fill limiter) are common safety features in LPG cylinder valve assemblies.

LPG expands approximately 270 times its liquid volume when it vaporizes. This significant expansion ratio is crucial to understand for proper storage and handling of LPG, as it can lead to pressure buildup in confined spaces if not properly managed.

Class B fire extinguishers are designed for flammable liquid and gas fires. They typically use dry chemical agents or carbon dioxide to suppress the fire by interrupting the chemical reaction of the fire triangle. Classes A, C, and D are for ordinary combustibles, electrical equipment, and combustible metals, respectively.

The autoignition temperature of propane is approximately 470°C (878°F). This is the temperature at which propane will spontaneously ignite without an external ignition source. It's crucial to understand this property for safe handling and storage of LPG.

Using a lit match or open flame to check for gas leaks is extremely dangerous and should never be attempted. It can lead to explosions or fires. The other methods listed (soapy water solution, electronic detectors, and smell detection) are safer and recommended techniques for identifying gas leaks.

CNG is typically stored at pressures between 200-300 bar (2900-4350 psi). This high pressure allows for a significant amount of natural gas to be stored in a relatively small volume, making it suitable for use in vehicles and other applications.

While LPG can contain a mixture of gases, propane is typically the primary component of LPG. Butane is also commonly present, but propane is more widely used due to its lower boiling point, making it more suitable for various applications.