BS 4431:1989

This British Standard describes methods of test and sampling for liquefied anhydrous ammonia suitable for general industrial purposes.

NOTE 1 In the methods described the ammonia is sampled by volume but the calculations are by mass. The density has been taken as 0.68 g/mL, at about − 33 °C, at which temperature liquid ammonia has a vapour pressure of 10⁵ Pa¹). A corrective evaporation factor is applied in each case to allow for loss through sampling at atmospheric pressure.

Clause 2 describes a general method for collecting the test portion with minor variations given for particular methods.

Clause 3 describes a method for the determination of residue on evaporation, which applies to products giving a residue value greater than or equal to 100 mg/kg.

Clause 4 describes a gravimetric method for the determination of the oil content (non-volatile at about 105 °C), which applies to products having an oil content greater than or equal to 10 mg/kg.

Clause 5 describes a method for the determination of the oil content (non-volatile at about 105 °C) in which the method used for the isolation of the oil content is as described in clause 4, but the determination is made using infra-red spectrometry. This is more sensitive than the gravimetric method and applies to products with an oil content less than 10 mg/kg.

Clause 6 describes a method for the determination of the water content by the Karl Fischer method, which applies to products with a water content greater than or equal to 25 mg/kg.

Clause 7 describes the determination of carbon dioxide by a titrimetric method, which applies to products with a carbon dioxide content greater than or equal to 15 mg/kg.

Clause 9 describes a method of sampling for the subsequent determination of oxygen by gas chromatography.

In Appendix A guidance is given on the sampling of anhydrous ammonia and in Appendix B a method for the determination of the evaporation factor, F, is described.

NOTE 2 The titles of the publications referred to in this standard are listed on the inside back cover.

Describes methods for sampling, determination of oil, water, and carbon dioxide and determination of residue on evaporation.