АкушерствоАнатомияАнестезиологияВакцинопрофилактикаВалеологияВетеринарияГигиенаЗаболеванияИммунологияКардиологияНеврологияНефрологияОнкологияОториноларингологияОфтальмологияПаразитологияПедиатрияПервая помощьПсихиатрияПульмонологияРеанимацияРевматологияСтоматологияТерапияТоксикологияТравматологияУрологияФармакологияФармацевтикаФизиотерапияФтизиатрияХирургияЭндокринологияЭпидемиология

XX. Read the text and give its short summary

Odorants

The gas industry has long recognized the inherent danger of a gas leak. To provide means of early leak detection, the industry adds odorants to their products for identification of a leak.

Neither natural gas nor the liquid propane (LP) family of gases has a natural odour. It is necessary to add an odorant to these gases so that the consumer can detect their presence. According to the NFPA Standard 58, the odorant should be characterized by a distinctive odour so that presence of gas can be detected at less than one fifth of the lower limit of flammability of the gas.

An odorant should be chemically stable with a high odour intensity under all conditions. It should have a distinctive odour and be nontoxic and nonirritating in combination with the gas or with the products of combustion. It should be easily introduced into the system at a low cost per gallon. Commercially available odorants are generally a compound containing sulphur, which provides the distinctive odour.

The effectiveness of the odorant is measured by its ability to be detected by the average person under normal conditions. The dosage is such that the presence of the gas can be detected long before the lower flammability limit of the gas is reached.

This does not automatically eliminate any danger of an explosion, but it does allow the consumer early detection of small leaks before sufficient gas has accumulated to cause a major explosion.

XXI. Translate the microtext:

Дата добавления: 2015-09-18 | Просмотры: 690 | Нарушение авторских прав