The perchloric acid fume hood is specially designed to handle the regular use of hot perchloric acid, hot nitric acid or perchloric acid. Does not handle sulfuric acid, acetic acid, organic solvents, or any combustible materials.

This professional fume hood has a PP liner surface (including work area) and a cleaning system, which is scattered throughout the fume hood. When heated, perchloric acid evaporates and condenses in the fume hood, air duct and fan assembly. In addition to being highly corrosive, the condensed steam can form explosive perchlorates and esters with fume hood gaskets, grease and other collected materials. Therefore, the PP surface improves cleanliness and the cleaning system can remove any explosive compounds that may be formed on the inner surface.

PRINCIPLE

SPECIFICATION

1.1 Fume hood body: High quality PP (polypropylene) sheet, excellent acid and alkali resistance, and excellent weather resistance.welded by PP board. Hood cabinet (air exhaust cabinet) adopts double-layer structure, and the interlayer between the outer casing and the inner lining (interlayer width is about 100mm), which can accommodate water, electricity and gas pipeline systems, and can ensure the airtightness and protection of the cabinet. The operation table and the bottom cabinet (connected to the exhaust pipe can be designed as a suction type), that is, the table top is placed on the base cabinet, and the upper cabinet is placed on the table top.

1.3 Baffle: Its material and thickness are the same as the inner liner. The installation position and angle of the baffle can make the exhaust distribution even and there is no dead angle. In the standard condition, the proportion of exhaust air at the upper and middle and lower air outlets of the deflector is about 50±10% to ensure that the gases of different specific gravity can be effectively discharged. The air volume of the middle and lower air outlets can meet the needs of different experiments. (The shape, size and hole position of all the same type and size of fume cupboard deflector can be interchanged arbitrarily).

1.4 Baffle fixing seat: It is made of acid and alkali resistant PP(polypropylene) material molded baffle fixing seat assembly. Its performance meets the following requirements:

◇ The back plate fixing seat and the baffle fixing knob can be easily assembled, disassembled, maintained and cleaned from the front of the cabinet.

◇ If metal screws are used during assembly, they can be hidden and isolated to avoid contact with the gas in the cabinet.

◇ The fixed seat has good stability, and its load-bearing capacity should be at least "100kg" (inclusive).

◇ The back plate fixing seat has the mounting hole design for the distillation grid kit. The stainless steel round tube bracket can be fixed by locking and tightening to facilitate the combination of the distillation grid kit. The front of each fume cupboard is equipped with digital numbers. The machine tool is precision machined, punched and formed to ensure that the moisture of large particles does not overflow, and the cabinet can be kept clean.

1.5 Vertical sash:

◇ The glass is made of acrylic, and it is wrapped around the edges.

◇ The track is made of plastic material and is designed to be inclusive.

◇ Each fume cupboard Sash adopts the design of double steel cables on the left and right sides. The steel cables are uncoated 304 stainless steel cables with a diameter of 2.5mm or more. (Inclusive) the above is not broken to ensure the safety of long-term use.

◇ Adopting a single counterweight box design, its up and down travel tool track is limited.

◇ Made of PP plastic material, the conical constricted air collecting hood is formed with a rectangular opening at the bottom. The diameter of the outlet pipe at the top of the fume hood is about 2*∮12", and the height of the outlet connecting pipe is more than 50mm (inclusive), which is convenient for air duct casing. Connection, the gas collecting hood has a good conical gas gathering angle and smoothness, the ratio of the length of the bottom elongated opening to the diameter of the top circular outlet is at least 2:1, and the conical angle is at least 30 degrees (inclusive) or more. In order to obtain good gas gathering uniformity and low pressure loss.

◇ The full-cover lamp holder is made of 1.0mm thick (and above) number 304 stainless steel sheet machine (with heat dissipation hole design), and the bottom is equipped with a 5mm thick matte acrylic glass, which can isolate the contact with the gas in the cabinet. , and has the function of pressure relief port.

CIRCULATING WATER DILUTION SYSTEM

In the experiments carried out in perchloric acid fume hoods, there may be an aerosol release process of perchloric acid, so the fume hood needs to be ventilated under the conditions of rated high air volume exhaust, with a design value of 1300 CMH, perchloric acid and ventilation. The alkaline water after the deflector of the cabinet is mixed and contacted, and the chemical reaction is:

HClO4+NaOH====NaClO4+H2O

The neutralized product is a neutral product with a pH of 7-14, so the designed recycling system is made of chemically resistant materials.

A buffer tank is arranged at a lower part of the fume hood, and a PP water pump is connected to the outlet side, and the water pump is connected with the atomization pipe behind the baffle, and the water pump outputs the alkali liquid to the atomization tube in the form of medium pressure, and forms a fine water droplet after passing through the atomization tube. The gas is mixed with the perchloric acid gas to complete the chemical reaction. The product is recirculated into the buffer tank of the water pump through the technical interlayer by the gravity.

OPERATION PROCESS

The system needs to be pre-checked before use, including the following:

1) The water tank should be filled with alkaline water (NAOH 50% solution), and tested with PH reagent, and the PH value recorded.

2) Check that all valves in the circulating water system are all open. If the valve in the circulating system of the pump is closed, the circulating pump must not be started.

3) Whether the test of perchloric acid is prepared in the fume hood, the fume hood needs to have the rated exhaust air volume (the average surface wind speed is between 0.5-0.8m/s, which needs to be detected by hand-held anemometer)

4) Turn on the pump start button, at which point the circulating water is evenly distributed in the form of water droplets behind the deflector.

System operation flow after the experiment is completed

1) The perchloric acid experiment in the fume hood has been completed

2) Turn off the water pump and test with PH test paper, and record the PH value for the reference value of the next experiment. (When the pH is below 6, the buffer needs to be replaced)

3) Close the valve on the water system

4) Turn off the exhaust of the fume hood

PROTECTION& TREATMENT

Operational precautions: closed operation, local exhaust. The operation is as mechanized and automated as possible. Operators must be specially trained to strictly follow the operating procedures. Operators are advised to wear a filter-type gas mask (full face mask) or self-contained breathing apparatus, a polyethylene protective suit, and rubber gloves. Keep away from fire, heat, and smoking in the workplace. Prevent vapors from leaking into the workplace air. Avoid contact with acids, bases, and amines. Pay particular attention to avoid contact with water. Lightly load and unload during handling to prevent damage to packaging and containers. Vibration, impact and friction are prohibited. Equipped with the corresponding variety and quantity of fire-fighting equipment and leakage emergency treatment equipment. Empty containers may be harmful residues. When diluting or preparing the solution, the acid should be added to the water to avoid boiling and splashing.

PRECAUTIONS

This type of fume hood is a special type of fume hood for perchloric acid. Users are required to carry out experiments according to the chemical characteristics of perchloric acid. The experiment should follow the relevant experimental procedures. Do not directly carry high concentration and high dose in the fume hood. Perchloric acid experiment. The alkaline water and circulation system behind the baffle of the fume hood is a neutralization system, which is to ensure that no high concentration of perchloric acid residues are accumulated in the fume hood, causing chemical reactions such as burning, explosion or mass heating. There is no guarantee that national standards for exhaust emissions will be met. In order to meet the national environmental protection corresponding emission standards, a secondary neutralization reaction is required on the fan side.

FIRST-AID

Skin contact: Immediately remove contaminated clothing and rinse with plenty of running water for at least 15 minutes. Seek medical attention.

Eye contact: Immediately lift eyelids and rinse thoroughly with plenty of running water or saline for at least 15 minutes. Seek medical attention.

Inhalation: Remove quickly from the scene to fresh air. Keep the airway open. If breathing is difficult, give oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention.

Ingestion: Rinse mouth with water and drink milk or egg white. Seek medical attention.

MAINTENANCE

◇ If the pump leaks, please stop the experiment immediately, and contact the contractor for timely maintenance;

◇ The circulating water treatment system needs to regularly clean the sludge in the buffer tank;

◇ The pump must not be idling without liquid;

◇ The pump should not be operated when the pipeline valve is not open;

◇ The pump must not run a chemical solution with a temperature exceeding 50 °C;