[No bubble water sample collector]
In the water quality analysis experiments such as environmental monitoring, the experimental content of collecting water samples is often involved. Now there are many kinds of finished samplers on the market, and there are simple water-collecting devices such as wide-mouth glass bottle weighting hammers, etc. More complex autosampler, electric sampler and deep water sampler. At present, the more commonly used sampler is a simple sampling device such as a wide-mouthed glass bottle weighting hammer, which is low in cost and can meet the basic requirements of the experiment, but it is fragile, inconvenient to carry, and troublesome to use. It is operated by skilled personnel, so it is less operative for students. The more complicated automatic sampler, electric sampler and deep water sampler are special equipments developed according to the needs of special purposes. The price ranges from several thousand to several tens of thousands, so the price is expensive and cumbersome, not suitable for large Area use.
Now, based on the premise of meeting the basic requirements of the experiment, combined with the basic principles of the experiment, the actual situation of the students' practical ability and the market reality, we have developed a DO-1L bubble-free water sample collector with a cost of 200 yuan. It is an experimental equipment designed for the collection of samples in our dissolved oxygen determination experiments and comprehensive experiments. The technical key of the water sample collector is that in the process of transferring the water sample from the natural state to the water sample collector, the disturbance of the air and the sample must be avoided, that is, the air bubbles cannot be mixed in the sample.
Collecting water samples is a key step in the whole process of water quality monitoring. Different monitoring items have different sampling requirements. The key to sampling operation should be based on the principle of not changing the original state of the water body. Practice has shown that the water sample used to determine dissolved oxygen must be collected using a dedicated sampler and not directly perfused with a dissolved oxygen bottle. When using a general bucket of water to collect water samples, the concentration of dissolved oxygen in the sample that has been changed by the sampler unconsciously is disturbed by the water surface; when the water sample is transferred to the dissolved oxygen bottle, direct pouring will make the sample contact. Oxygen is easily dissolved into the water through the gas-liquid interface when the air is disturbed.
The ideal result can be achieved with the DO-1L bubble-free water sample collector. When the sampler is used, according to the position of the sampling point, connect the rope of the appropriate length and the rubber exhaust pipe with the switch valve, and when it sinks to the target position in the water, start to open the exhaust valve slowly. The water pipe is directly introduced into the bottom of the water sample collection chamber, so that the liquid level of the water sample is slowly raised from the bottom until it is full, and the sampler is raised to the water surface, and the water inlet and the vent hole are closed and sealed for supply. Subsequent analysis test.
After entering the laboratory, open the water inlet and vent hole, and change the short hose on the original vent hole. Fill the tube with the sample by siphon method, and insert the hose port into the bottom of the dissolved oxygen bottle, slowly inject it. Water sample, until the water sample overflows from the mouth of the bottle 1~2 times the volume, and then slowly withdraw the hose. After filling the bottle, it can be stoppered or preserved. After the stopper, there should be no air bubbles in the sample bottle. Since the surface of the water sample is undisturbed during the collection process and the bottling process, no oxygen escapes or dissolves in the liquid surface, and the dissolved oxygen in the sample can maintain the true content level in the raw water body.
The design of the equipment is based on scientific principles, and the overall appearance of the equipment and the functional areas are planned. Through reasonable design, the functions such as the inlet pipe, the vent hole and the sampling port (sample extraction hole) are solved, and the reasonable position and space ratio of the water sample collection room and the weight room in the whole equipment and Heavy hammer material determination and fixing issues. The whole equipment is processed with colorless transparent plexiglass, which makes it easier for students to observe the internal structure of the equipment more clearly, which is easy to stimulate students' curiosity, which makes it easier for students to learn and explore their desires. The student union will conduct a self-help experiment to simulate the collection of water samples in the pool, observe and understand the whole process of water flow during the collection of water samples, and carry out more in-depth exploration and research in combination with the working principle, propose improvements in experimental equipment, and study and design more individuality. Specialized experimental equipment. This learning process can not only demonstrate the reliability of equipment operation, but also encourage students to actively learn, understand and cite relevant professional knowledge to develop or improve experimental equipment, fully embodying the important role of practice links in understanding and citing theoretical knowledge. Improving students' hands-on ability and promoting the cultivation of their innovative thinking have played a positive role.
This equipment can be used not only to collect samples of dissolved oxygen determination experiments in water, but also to collect samples of dissolved gases in water such as carbon dioxide and other general-purpose samples. It has no special requirements for the sampling environment, and can be used for stratified sampling of the water body to be tested. It is a special equipment for collecting various water samples in the field. The utility model has the advantages of beautiful appearance, novel design, ingenious design, small volume, low cost, wide application, stable performance, convenient carrying, simple and convenient operation, thereby reducing the difficulty of sampling, and more convenient for students to collect samples of natural water.
Because this equipment is mainly designed for student experiments, it is especially suitable for collecting water samples in the field of experimental teaching in colleges and universities. It is also suitable for environmental protection departments and other relevant departments to collect water samples for analysis of water quality or aquatic plankton. . This equipment has been patented, patent number ZL201320545028.4.
Name of the work: Bubble-free water sample collector
Completion unit: Tongji University, National Experimental Teaching Demonstration Center of Environmental Science and Engineering, Tongji University
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