This standard specifies the equipment and operation methods for taking representative laboratory samples of liquid anhydrous ammonia from cylinder tankers or storage tanks. GB 8570.1-1988 Taking laboratory samples of liquid anhydrous ammonia GB8570.1-1988 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Liquid anhydrous ammonia
Taking a laboratory sample
This standard is equivalent to the international standard ISO7103-82 "Industrial liquid anhydrous ammonia--Sampling.
UDC 661.518
GB 8570.1-88
-Taking laboratory samples".
This standard specifies the equipment and operation methods for taking representative laboratory samples of liquid anhydrous ammonia (liquid ammonia) from cylinders, tank trucks or storage tanks. www.bzxz.net
1 Key points of operation
Transfer the liquid ammonia to a pre-cleaned, dried and evacuated stainless steel bottle to the specified amount allowed by safety. At room temperature, the filling volume should be strictly controlled not to exceed 75% of the cylinder volume. 2 Instruments and Equipment
2.1 Sampling Equipment
2.1.1 Sampling Cylinder (see Figure 1): Made of stainless steel, with an effective volume of not less than 1L and a pressure resistance of not less than 3MPa. AB
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Figure 1 Sampling Cylinder
The volume of the cylinder is verified by filling it with water. The cylinder is equipped with two needle valves A and B, which are connected to two stainless steel pipes in the bottle respectively, one of which is connected to the bottom of the bottle, and the length of the other is determined by the safe filling volume of liquid ammonia in the bottle (1 and 3.3). The design of the cylinder should take into account easy cleaning and drying. For easy carrying, the valve port should be equipped with a cap. Note: ① The volume of the cylinder should be determined according to the amount of liquid ammonia sample required for all tests. ② The inside of the cylinder should be checked frequently. If it is found to be unclean, it can be washed and dried with running water, then washed several times with pure acetone, and finally flushed with nitrogen (2.5). At the same time, the gas tightness of the cylinder should also be checked. For this purpose, it can be immersed in water and filled with ammonia to about 3MPa for inspection. 2.1.2 Connecting pipe (see Figure 2) 1): A stainless steel pipe with an inner diameter of about 5mm, of moderate length, is welded to a stainless steel branch pipe with the same inner diameter close to one end to form a T shape. Each end is equipped with a threaded joint, one end is connected to the liquid phase valve of the liquid ammonia container, and the other end is connected to the cylinder valve A (2.1.1). Instructions for use:
1) ISO7103 equips the connecting pipe with a three-way switching valve. This standard uses a T-shaped pipe with a needle valve instead according to the actual situation in my country. Approved by the Ministry of Chemical Industry of the People's Republic of China on December 2, 1987
Implementation on September 1, 1988
GB8570.188
Another needle valve C is installed on the branch pipe. By opening and closing valve C, liquid ammonia can flow from the container into the atmosphere or the sampling cylinder, and the sampling cylinder can be opened to the atmosphere when the liquid phase valve of the liquid ammonia container is closed. The connectors used should be corrosion-resistant to nitrogen, such as hard rubber, high-lead alloy, and copper-containing materials are not required. Figure 2 Assembly diagram
1-Liquid nitrogen container; 2-Container liquid phase valve; 3-Connecting pipe, 4-Sampling cylinder 2.2 Constant temperature + drying box: temperature control requirements 105~110℃. 2.3 Day: Sensitivity 1g.
Vacuum pump: can quickly evacuate the cylinder (2.1.1) to a pressure of about 100Pa. 2.4
2.5 Nitrogen (GB3864-83): 5A separation and drying 2.6 Freezing bath: solid carbon dioxide (+ ice) and 1 industrial alcohol are used as refrigerants, the cooling temperature is -35~-40℃, and a thermometer is used.
3 Operational procedures
Preparation of steel cylinder and connecting pipe
Operate in the following order:
3.1.1 Open needle valves A and B, connect the steel cylinder (2.1.1) to the connecting pipe (2.1.2), close needle valve C, and purge the assembled sampling device with 1% dry nitrogen (2.5) at room temperature. 3.1.2 Move the sampling device into a constant temperature drying oven at 105~110℃, and continue to purge with 1% dry nitrogen for at least 30 minutes through the steam inlet pipe connected to the connecting pipe and through the wall hole of the constant temperature drying oven. 3.1.3 Close needle valve A, remove the steel cylinder, connect the vacuum pump (2.4) to the outlet needle valve B, and evacuate until the pressure in the steel cylinder reaches 100Pa or less, and maintain this pressure for at least 30 minutes. 3.1.4 Close needle valve B and cool the steel cylinder. 3.1.5 Weigh the empty cylinder on a balance to the nearest 1g. 3.2 Sampling
Place the cylinder (2.1.1) in a freezing bath at about -35℃ and cool for 10 to 15 minutes to prevent the valve from frosting. Tightly connect the connecting pipe (2.1.2)
GB 8570.1-88
to the liquid phase valve of the liquid ammonia container, and connect the other end to needle valve A, and tighten the connection. Before opening the liquid phase valve of the liquid ammonia container, open needle valve C first to open it to the atmosphere. Carefully open the liquid phase valve of the liquid ammonia container to let the liquid ammonia flow out, and discharge the air in the connecting pipe through needle valve C. After the free flow of liquid ammonia purifies the sampling tube, close needle valve C, open needle valve A, and let liquid ammonia flow into the cylinder to the specified safe filling volume. Close needle valve A and the liquid phase valve of the liquid ammonia container, open needle valve C, and after the liquid ammonia in the connecting pipe is discharged, remove the steel cylinder. After sampling, immediately check the liquid ammonia filling amount of the steel cylinder according to 3.3. 3.3 Filling amount check
After calculating the mass according to the volume of the steel cylinder (2.1.1) and the density of liquid ammonia (g=0.68g/ml), use a balance to weigh the mass of the steel cylinder after sampling, and weigh it to 1g, thereby determining the amount of liquid ammonia taken. If the sampling amount exceeds the specified limit, the excess part shall be discarded as follows: After the needle valve B is connected to the rubber hose, put the steel cylinder vertically (the needle valve is on top), carefully open the needle valve B, let the excess liquid ammonia flow out, and then close it when ammonia vapor appears.
Remove the rubber hose and weigh the steel cylinder again, and weigh it to 1g. Additional remarks:
This standard is under the jurisdiction of the Shanghai Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard was drafted by Shanghai Chemical Industry Research Institute and Wujing Chemical Plant of the Ministry of Chemical Industry. The main drafters of this standard are Yin Yongkang, Jin Zhigen, Yao Bingsheng, Liu Miaode and Zhang Wenwei.
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