Common troubleshooting methods for laboratory instruments

1. When the grinding mouth of a glass instrument cannot be opened due to sticking, the following methods can be used for handling.

Tap on one side of the grinding mouth with a wooden lighter tap, so that it gradually loosens off due to shock. For cemented reagent bottles, grinding plugs of separatory funnels, etc., the stopper and bottle mouth of the instrument can be clamped at the corners of the experimental table or wooden table, and then lighter in the direction of about 70° with the axis of the instrument. Small slamming, while rotating the instrument intermittently, and so repeatedly manipulated several times, generally can open firmly cemented mouth.

Heating some of the fixed grinding mouth, the inconvenience of knocking or knocking can be invalid, the outer layer of the cemented part can be heated, so that it expands and heat with the inner layer. For example, use a hot, damp cloth to “heat-up” the cement.

Use a hair dryer or a mobile flame to bake the ground and so on.

If the bottle contains unfavorable heat or flammable substances, it is advisable to use a rope of knots, one end of which is tied to a fixed object such as a door and window handle, and then turn the rope clockwise around the cap, and then pull the rope tightly. At the other end, the bottle cap can be opened by holding the bottle in one hand and pushing hard forward.

When the screw cap can't be opened, it can be baked with a hair dryer or a small flame near the cap to make it expand by heat, and then it can be used to wrap the cap and forcefully unscrew it.

2. When the thermometer or glass tube is glued together with a rubber plug or hose and it is difficult to pull out, use a small screwdriver or a knife tip to insert a thermometer or glass tube and a rubber plug or hose. Between the time, let it form a depression, and then drop a few drops of water, so manipulate and expand along the thermometer or near the glass tube, at the same time gradually deepen, and soon will be pulled out. It can also be used with a driller that can just fit into a thermometer or glass tube, put a little glycerine or water on it, put it in from one end of the thermometer, gently press it, and push it while rotating. When it is difficult to roll, pull it out and put on the lubricant. , Inherit rotation, repeat several times, then you can pull out the thermometer or glass tube.

For acidic dirt that is insoluble in water, such as organic acids, phenolic deposits, etc., it can be washed after soaking in alkaline solution; for alkaline dirt that is insoluble in water, such as metal oxides, scales, etc., it can be cleaned after soaking in hydrochloric acid; if it is Potassium permanganate deposits may be washed with sodium sulfite or oxalic acid solution; manganese dioxide deposits may be dissolved with concentrated hydrochloric acid; dip with iodine may be soaked with potassium iodide solution; acid silver stains may be soaked in sodium thiosulfate solution and then washed; Silver or copper after silver mirror or bronze mirror reaction can be dissolved after adding dilute acid and micro-heat; tar or resinous dirt can be immersed in organic solvents such as benzene and esters and then cleaned by ordinary methods. For glass instruments that cannot be cleaned by the above method, dilute hydrofluoric acid may be used to infiltrate the dirt edges, and the dirt will fall off from the thin layer of glass that has been eclipsed and then cleaned with purified water. However, the glass is eroded, but the damage is small and generally does not affect the inherited use.

3. Crystals precipitated on the inner wall of the dissolving flask When refluxing or concentrating the solution, crystals often precipitate on the inner wall of the flask above the liquid surface, and adhere firmly. Not only cannot participate in the reaction, but sometimes the heat is not disturbed. Gradually decompose discoloration. In this case, the flask can be gently shaken, and the internal solution can be infiltrated and crystallized to dissolve it. If the flow of the device is limited and the flask cannot be shaken, a cold, wet cloth may be applied to the top of the flask to dissolve the precipitated crystals as the solvent condenses and flows down the walls.

4. Elimination of Emulsification When using a separatory funnel for extraction and washing operations, especially when the organic matter is washed with an alkaline solution, it is difficult to separate because the emulsification phenomenon does not cause delamination after vigorous shaking. If the degree of emulsification is not severe, the separating funnel can be slowly shaken in the horizontal direction and then left to stand still for a while to eliminate the foam at the interface and promote delamination. If there is still no stratification, a suitable amount of water can be added and then shaken horizontally or left overnight to clear a clear interface.

If the density of the solvent is close to that of water, emulsification with water can easily occur during extraction or washing. At this point, an appropriate amount of B can be added thereto to reduce the density of the organic phase, thereby facilitating delamination. For the emulsion of water-soluble primary esters and water, it can be promoted by adding a small amount of inorganic salts such as sodium chloride and ammonium sulfate.

5, rapid drying equipment When the experiment is in urgent need of using dry equipment, and no time with the conventional method of drying, you can first use a small amount of absolute ethanol to flush the inner wall of the instrument twice, and then flush with a little acetone to remove residual ethanol, and then use Hair dryer blow drying for a moment, you can achieve the drying effect.

6, remove the special dirt on the instrument When the glass is bonded to a special dirt, with the general method of washing is difficult to remove, you should first distinguish the nature of the dirt, and then targeted treatment.