LPG AND CNG CYLINDER

FOR LPG CYLINDER

LPG Cylinder is an essential item for filling liquefied petroleum gas used for cooking purpose. The body of LPG cylinder is deep drawn in two pieces then these are welded together to make a compact unit without any leak and defect etc. LPG cylinders are in use in 5 Kg., 12 Kg., 14.2 Kg. & 19 Kg. capacities. To ascertain the quality, safety and performance certain regulations are applicable such as BIS standardization and Explosive License etc. While all the cylinders are spray-painted with a signal red colour. BPC cylinders have yellow ring around the bung. HPC cylinders in blue ring and IOC cylinder are fully red. In case of 19 Kg. cylinders the top is painted olive green. The cylinders carry their complete history with regard to their serial number, Tare/ Gross weight, water capacity, ISE monogram test date, manufacturer identification and year of manufacturing.

SIZES OF LPG CYLINDER

LP Gas cylinders can come in many different sizes depending on the application. The gross weight of an LP Gas cylinder is often one of the limiting factors in selecting the size, especially for domestic applications. The diameter is also a very important factor because it has implications with the dimensions of the conveyors in the filling plant, and the pallets and racks used for storage etc.

For domestic use, cylinders typically will have capacities ranging from 4kg to 15kg whereas for commercial and industrial use, these will range from 45kg to 50kg. Smaller cylinders i.e. 1kg to 3kg capacities are used for camping equipment and in developing countries where they often serve as an entry level for LP Gas applications in low income households – mainly for cooking. LP Gas cylinders will almost always be used in the vertical position although forklift cylinders are typically designed to be used horizontally with capacities ranging from 15kg to 22kg.

Cylinder ApproximAte size dimensions lpG supply typiCAl use

4kg (3.7kg)
9.5 litre water capacity
8 litre product capacity
Tare weight 5kg

310mm height x 260 mm diameter

Exchange
Filled at some retail outlets

Barbecue
Outdoor heating
Camping
9kg (8.5kg)
22 litre water capacity
18 litre product capacity
Tare weight 8kg

480mm height x 310mm diameter

13.5kg
32 litre water capacity
26 litre product capacity 550mm height x 375 mm diameter Exchange Cooking
Tare weight 13.9kg
15kg

18kg 15kg
36.7 litre water capacity
29 litre product capacity
Tare weight 9.7kg
735mm height x 300mm diameter

Exchange
Filled on some customer sites

Forklifts
18kg
43 litre water capacity
35 litre product capacity
Tare weight 18kg
840mm height x 310mm diameter
20kg
49 litre water capacity
38 litre product capacity
Tare weight 19kg
860mm height x 310mm diameter

45kg
110 litre water capacity
83 litre product capacity
Tare weight 33 to 42kg

1239mm height x 374mm diameter

Exchange
Cylinders are permanently installed and filled on site by tanker

Residential and commercial gas appliances
Cylinder ApproximAte size dimensions lpG supply typiCAl use

90kg
215 litre water capacity
170 litre product capacity (filled by volume via tanker)
Tare weight 70kg

1340 height x 508mm diameter

Cylinders are permanently installed and filled on site by tanker

Residential and commercial gas appliances

210kg 190kg
450 litre water capacity
360 litre product capacity (filled by volume via tanker)
Tare weight 125kg

1370mm height x 760mm diameter

Cylinders are permanently installed and filled on site by tanker

Residential and commercial gas appliances
210 kg
499 litre water capacity
400 litre product capacity (filled by volume via tanker)
Tare weight 143kg

1454mm height x 760mm diameter

CONSTRUCTION OF LPG CYLINDER

A LP Gas cylinder consists of a few basic parts, namely – shroud (collar or handle), bung, body and foot ring. Each part has a specific function and should be designed and manufactured to meet its purpose. A poor design can result in cylinders being easily damaged and/or injury to users.

1. Body

The cylinder body holds the contents of the cylinder. It is the main component which is subjected to the pressure developed by LP Gas inside the cylinder

The body is designed concave to withstand pressure with either tori-spherical or semi-ellipsoidal ends. The wall thickness of the body is calculated using the formula prescribed by the design code (see 4.2). The capacity of the body is expressed in litres of water capacity. When designing the LP Gas capacity of the cylinder, the type of product, assessed temperature of the location As a rule, the maximum LP Gas content should not be more than 97% of its water capacity at the assessed temperature.

The body is generally made in either a two or three piece design depending on the size and application. Two-piece construction is common for domestic cylinders which consist of an upper and bottom cup. Higher capacity cylinders (i.e. cylinders for commercial and forklift applications) will generally require three-piece construction to avoid having to draw the cups too deep to meet the capacity. Cylinders are mainly designed for use in an upright position although some applications will require the cylinder to be horizontal (i.e. forklift cylinders). As the name suggests they are cylindrical in shape with typically only one opening, (some liquid withdrawal valves have two openings) where the valve is positioned.

2. Bung

The bung (also called the boss or neck-ring) is the opening on the cylinder which provides a connection to the valve. It should be located on the end of the cylinder and should be clear of any circumferential or longitudinal welds.

The bung can either be an internal type or an external type and it should be designed to minimise the protrusion of the bung above the cylinder unless it is designed for a screw on cap.

The thread should be specified to suit the valve thread intended to be used. It is recommended that only one thread specification should be used for the entire cylinder population to avoid intermixing of different valves.

For cylinders where the cooking appliance is directly connected on top of the valve e.g. 2kg to 3kg cylinder, the concentricity of the bung to the vertical axis of the cylinder is critical and should be kept within a maximum tolerance of 3mm.

3. Shroud

The purpose of the shroud (also called a collar) is to protect the valve from damage due to impact and when stacking cylinders on top of each other. It is also fitted to enable the cylinder to be handled. In the absence of a shroud, the valve should be protected using a removal cap which is also to be fitted when the cylinder is in transit.

Shrouds should be designed so that regulators can be connected easily and that the LP Gas hose is not bent when the regulator is connected.

Cylinders with self-closing clip-on valves typically will have shrouds totally encircling the valve while cylinders with hand wheel operated valves will have shrouds with openings to accommodate the connection of regulators.

The shroud should also be designed to allow one cylinder to be stacked on top of the other without the bottom of the upper cylinder touching the valve of the lower cylinder. The material should be robust enough to support the cylinders above it. There may be up to four cylinders stacked on top of the cylinder so the total gross weight of these should be accommodated by the shroud of the bottom one.

Shrouds should be fully welded to the cylinder unless the country legislation dictates otherwise. The weld attachments should be designed to prevent water being trapped which might lead to corrosion.

Hand holes in the shroud should be provided to facilitate handling of the cylinders. They should be designed to provide a comfortable grip when lifting and carrying the cylinder and prevent potential injury to the user.

If a pressure relief valve is fitted to the valve there should be an opening in the shroud to allow vented LP Gas to escape.

4. Foot Ring

The foot ring should provide stability to the cylinder when standing alone or if stacked on top of another cylinder. It also protects the underside of the body from touching the ground.

Foot rings should be designed larger than the outside diameter of the cylinder in order to minimise damage to the cylinder walls during handling and transit.

The foot ring should be designed to prevent water being trapped which might lead to corrosion. It should also have ventilation holes to prevent condensation building up on the underside of the body of the cylinder.

The material should be of sufficient thickness to resist deformation of the foot ring during handling and to support the weight of cylinders stacked above it.

5. Valves

There two basic types of LP Gas cylinder valves for vapour service, namely, self-closing, clip-on valves and hand wheel operated valves. They can come with or without pressure relief valves depending on local regulations.

(A) Self-Closing, Clip-on Valve

These are typically used for domestic cylinders where low cost and fit for service valves are required. Common types in the market are compact, bayonet, or snap on (snap tight) valves.

They can be fitted with excess flow limiters and/or anti-dirt tubes (also called eduction tubes). Because these valves are open-topped, plastic dust caps are recommended to be fitted during storage and transportation to prevent entry of foreign matter

(B) Hand Wheel Operated Valve

These valves are used both with domestic and commercial cylinders and are designed for different applications i.e. liquid fill, liquid service and vapour service. The outlet connection of hand wheel operated valves can come in different forms e.g. CGA 510 (or F.Pol), CGA 555 (or M.Pol), ACME, NPT, etc. When both vapour and liquid connections are on the same valve, they must be designed differently for clear distinction. Liquid service valves are fitted with a tube and an excess flow limiter.

Hand wheel operated valves can accidentally be opened and it is recommended to fit a gas tight plug after filling while the cylinder is in transport or storage.

FOR CNG CYLINDER

CNG is the compressed form of Natural Gas, which is mainly composed of methane [CH4]), which is less than 1% of the volume it occupies at standard atmospheric pressure so that large volume of gas can be stored in CNG cylinder. Final filling pressure of CNG in the vehicle cylinder is limited to 200 bar.

CNG is successfully used as a fuel in our transport system from Decades, more popularly termed as “Green Fuel”. CNG is widely used in Auto rickshaws, Cars & Buses. For use in Automobiles as fuel, it is compressed to a pressure of 200-250 bar to enhance the vehicle on-board storage capacity. CNG or Compressed Natural Gas is a fossil fuel substitute for petrol, diesel, or LPG. CNG is more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill.

CNG cylinders are strong and light weight and undergo stringent cyclic testing to assess fatigue strength, usage life and to ensure safety and reliability under extreme climate conditions. A wide range of CNG cylinders are designed and designed and manufactured to comply with national and international standard (Reinforcement.com, 2007). High-quality stainless steel CNG cylinders and cascade of cylinders are available for different capacities and various kinds of vehicles, like three-wheelers, cars, buses and delivery vehicles as shown in Figure 24 a and b.

The storage tanks for compressed natural gas (CNG cylinders) must be strong, lightweight, and resistant to impact and temperature. Cylinders can be divided into the following three groups, depending on the materials used in their manufacture:

• Metallic

• Mental-composite (metal liner strengthened by polymer composite material; and

• Composite (polymer liner strengthened by polymer composite material).

Gas cylinders are the heavier portion of alternative fuel systems which adds more weight to vehicle unlades weight. In search of innovative materials for gas cylinders, composite material has been the front runner in reducing weight of the vehicle, thereby reducing fuel consumption significantly. This report describes the various types of composite cylinders, their design & test requirements, merits and demerits of each type of composite cylinder.

This report explains various new and effective technologies in Cylinders that are available internationally, its regulatory requirements and usage. In India Type 1, 2, 3 have been successfully used in Indian Automotive Industry Chief Controller of Explosives (CCOE), Nagpur is the approval authority for CNG Cylinders in India.

This unique report will also provide you with valuable information, insights about vehicles with Type 4 Cylinders, history of composite cylinders and detailed analysis of all the four types of CNG Cylinders

Current status of adoption of composite cylinder technology in India and worldwide, such as number of composite cylinder manufacturers in world, level of introduction of composite cylinders in different types of vehicles and incidents happened due to composite cylinders are also described in this report. Based on review of composite cylinder technology, it is concluded that all-composite cylinder technology (i.e., Type-4 cylinders) is the best solution for light weighting of automotive heavy commercial vehicles such as buses without compromising on safety.

Type of CNG Cylinders

Cylinder types include:

1. Type 1
2. Type 2
3. Type 3
4. Type 4 a