Determination of trace water in ethylene and propylene for industrial use (2)

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Note: The anolyte contains an appropriate amount of ethylene glycol (such as 10% of the total volume) to help absorb the trace water in the sample

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Note 1: Other capillary gasification devices and connection methods that can meet the technical requirements of this standard can also be used

Note 2: When measuring ethylene, the end of the cylinder without pressure gauge should be used as the gas outlet to connect to the capillary tube

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Note: It is not necessary to switch the cylinder valve during the propylene determination process, but to control the sample injection by controlling the capillary port in and out of the sealing gasket

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6 Expression of results

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6.
1 Express the moisture content (c ₁ ) in the sample by mass concentration (mg/kg ), and calculate it according to formula (1):

Where:

m ₁ —The absolute value of moisture displayed by the instrument, ug;

m—the mass of the sample, g
.

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2 Express the water content (c ₂ ) in the sample by volume concentration (mL/m³ ), and calculate according to formula (2):

Where:

M—The relative molecular mass of ethylene or propylene (28.
05 for ethylene and 42.
08 for propylene);

18.
01—The relative molecular mass of water
.

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3 Take the arithmetic average of the two repeated determination results as the analysis result, and round it to 0.
1 mg/kg according to GB/T8170-1987
.

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7 Repeatability

In the same laboratory, by the same operator, using the same instrument and equipment, the same sample with the moisture content in the range of 1mng/kg-50mg/kg is repeated twice.
The result is obtained under the 95% confidence level.
The difference should not be more than 3mg/kg
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