In Hong Kong, town gas is produced from naphtha and natural gas. Its major components are hydrogen, methane, carbon dioxide and a small amount of carbon monoxide. Its calorific value is about 17.27 MJ/m3 and its flammable limits are approximately 4.5 ~ 44.3%. The Wobbe Index of town gas is 24. It is colourless, odourless, flammable, explosive and toxic. As town gas is lighter than air (weights approximately 0.52 times the weight of air), it can dissipate in the air easily. For safety reasons, town gas has a special odour added to help detect leaks. Town gas is produced at two production plants: the Tai Po Plant and the Ma Tau Kok Plant. It is supplied to users through a network of pipelines. Various pressure-regulating facilities are set up in the gas supply network to ensure a stable supply of town gas and steady gas pressure. Real-time monitoring of the Hong Kong gas supply network is facilitated by remote monitoring technology.

(Source: The Hong Kong and China Gas Company Limited)

LPG is the abbreviation of "liquefied petroleum gas". It is a mixture* of propane and butane. The calorific value of domestic LPG is about 116 MJ/m3 and its flammable limits are approximately 1.8 ~ 9.5%. The Wobbe Index of LPG is 84. LPG is colourless, odourless, non-toxic, flammable, explosive and heavier than air. As it is approximately 1.91 times the weight of air, it tends to accumulate on the ground level. For safety reasons, LPG has a special odour added to help detect leaks. Apart from being centrally supplied through a network of pipelines, LPG can be stored in liquid form in a cylinder. The LPG used in Hong Kong is imported from overseas and stored in LPG storage compounds. It is subsequently supplied to LPG users and LPG filling stations.

(Source: The Electrical and Mechanical Services Department)

 Town GasLiquefied Petroleum Gas
Materials / Components

Feedstocks: Naphtha and natural gas

Constituents: hydrogen, methane, carbon dioxide, and a small amount of carbon monoxide, nitrogen and oxygen

Propane and butane*
Calorific Value (MJ/m3) 17.27 116
Flammable Limits 4.5 ~ 44.3% 1.8 ~ 9.5%
Wobbe Index 24 84
Toxicity Toxic Non-toxic
Weight 0.52 times the weight of air 1.91 times the weight of air
Supply Method It is supplied through a network of pipelines. It is centrally supplied through a network of pipelines or stored in a cylinder in liquid form.

Remarks:
*  According to the interpretation of the Gas Safety Ordinance, Cap.51, LPG means any gas which is a mixture of :
   (a) hydrocarbons primarily consisting of butanes, butylenes, propane or propylene; or
   (b) all or any of the hydrocarbons referrred to in (a).
However, there is only negligible amount of propylene and butylenes in LPG.

Enquiries and Contact Us

Address Gas Standards Office, Electrical and Mechanical Services Department, 3 Kai Shing Street, Kowloon, Hong Kong
Office Hours Monday to Friday 8:30 a.m. to 6:00 p.m.
(Closed on Saturday, Sunday and public holiday)
E-mail info@emsd.gov.hk
Hotline 1823 Citizen's Easy Link
Fax 2576 5945