Laboratory ventilation cabinet exhaust and rehydration system operation and control requirements

First operation and control objectives In order to ensure the safety and health of personnel, laboratory ventilation equipment and systems must be done: 1. Effective and timely discharge of toxic gases and particles from sources of pollution.
. In order to prevent toxic gases and particles from being tested and harmful gases volatile during chemical storage from spilling into other spaces, laboratories are required to ensure a certain amount of negative pressure.
3. The airflow in the laboratory is well organized and the return air flow speed and turbulence can be controlled to a smaller extent to prevent the disturbance of indoor gas from causing gas to spill out of the exhaust cabinet.
4. The air rate in the laboratory can be effectively controlled and the indoor air should be fully replaced to ensure its freshness.
5. Ventilation system to fully consider the laboratory set up in the case of multiple exhaust cabinets at peak times at the same time use, night shift conditions under the small exhaust and other conditions, the ventilation capacity of the system should not only meet the requirements of large ventilation, but also take full account of its adjustment flexibility, to achieve economic operation of the system.
should consider the use factor of the equipment at the same time, so that the system equipment configuration is more reasonable, a large limit of energy saving.
6. Effective control of temperature and humidity in the laboratory, indoor noise should be less than 58 dbA, to provide a comfortable environment for staff.
2 Laboratory clean air ventilation cabinet exhaust and reflow system operation and control program 1. Ventilation cabinet scheme 1 to 12 floors of the general laboratory using bypass-type air volume ventilation cabinet (except for special requirements), 13 to 14 floors of the science and chemical laboratory using bypass-type air volume ventilation cabinet and variable air volume ventilation cabinet, the specific configuration can be seen in the design drawings.
ventilation cabinet should meet the relevant national norms and standards, and should be equipped with sensors and controllers (according to the monitored surface wind speed adjustment corresponding to the variable air volume valve opening degree).
2. 1 to 12 floors of the general laboratory ventilation cabinet system control usually close the ventilation cabinet exhaust and wind system on the electric closed valve (EVD).
When using the ventilation cabinet, through the manual opening of the associated lock on the ventilation cabinet to open the exhaust and re-air system electric air closed valve, by the fixed air volume valve control exhaust volume is constant;
3. 13 to 14 floors of ordinary laboratory ventilation cabinet system control (1) a single ventilation cabinet laboratory: the use of bypass ventilation cabinet, send, exhaust system using a dual steady-state fixed air volume adjustment mode to achieve the ventilation cabinet working state and idle state between the two different air measures.
When there are people in the laboratory and the ventilation cabinet is not used, the closed valve EVD is open, the dual steady-state fixed-air valve CVD2 is in low-grade state, to meet the indoor ventilation number is not less than 6 times / h requirements;
(2) multiple ventilation cabinet laboratory: the use of bypass ventilation cabinet and variable air volume ventilation cabinet, send, exhaust system using dual steady-state fixed air volume adjustment mode and variable air volume adjustment mode to achieve the ventilation cabinet working state and idle state of the air volume between the switching.
When there are people in the laboratory and the ventilation cabinet is not in use, the closed valve EVD is open, and the dual steady-state fixed air valve CVD2 is in low gear to meet the requirements of no less than 6 times/h of indoor ventilation.
When someone in the laboratory uses the ventilation cabinet, the closed valve EVD open state remains unchanged, such as the use of bypass ventilation cabinet, then the double steady-state fixed air volume valve CVD2 is in a high-grade state, to meet the exhaust requirements of the ventilation cabinet;
when there is no one in the room, manually close the closed valve EVD, saving energy.
4. The fan system controls the opening of any one of the clean air cabinets and interlocks to open the corresponding roof exhaust fan, while the fan delay stops when the airless ventilation cabinet is opened or used.
fan using pipe static pressure frequency control, the controller continuously monitors the static pressure in the pipe, by adjusting the wind turbine speed to constant static pressure, to ensure that more than one clean air type ventilation cabinet opened when the air pressure.
5. Other exhaust systems start before the air delivery system while the system is running, and the opposite is true when the system is switched off, when indoor airflow is disturbed.
Indoor pressure difference and the system set pressure difference value deviation, the air change control valve in the delivery and exhaust system will start quickly, self-adjust to the appropriate opening degree, rebalance the system pressure, accurate control of the pressure difference in the laboratory;
control unit 1. Used in the third ventilation system 1. The fixed air volume control valve (CVD) is applied to the air intake and exhaust volume control.
2. Dual steady-state fixed air volume control valve (CVD2) applied to the air intake and exhaust volume control.
3. The variable air volume control valve (VVD) is applied to the air intake and exhaust volume control.
4. A closed valve (EVD) that controls the opening or closing of the room delivery and exhaust system.
4 The ventilation system control unit should meet the requirements 1. The technical requirements of the fixed air volume valve (CVD, CVD2): a. the fixed air volume control valve should be pressure-independent, mechanical automatic adjustment device, the valve body is made of high-quality materials such as galvanized steel plate, the air volume of the fixed air volume adjustment valve can be strictly in accordance with the scale plate calibration of the air measurement, exhaust, and not affected by static pressure and wind volume changes in the pipeline.
b. The structure of the fixed air volume regulating valve body is the single valve plate throttle form, and the opening of the valve position is automatically adjusted according to the change of static pressure in front of the valve, thus ensuring a constant amount of air delivery.
c. The fixed air volume control valve shall be internally inserted or flanged and may be accompanied by an electric actuator to meet the requirements of dual steady-state fixed air volume regulation or remote control.
d. The fixed air volume control valve works within the pipe static pressure difference of 50 to 1000Pa and can be installed horizontally or vertically without position restrictions.
requirements for on-site installation, even if the entrance or exit conditions are not conducive to normal operation.
. The accuracy of the fixed air volume regulation valve flow adjustment should be less than 8% of the set air volume under different static pressure conditions.
f. The air gauge dial and pointer should be available outside the fixed air gauge control valve to display the flow scale, and the air volume can be set at will within the scale disc air volume range, and can guarantee the air gauge and the actual air volume error of ± 4%.
2. The technical requirements of the variable air volume valve (VVD): a. the variable air volume control valve body should use high-quality materials such as hot galvanized steel, bearings should meet the requirements of corrosion resistance, anti-wear, anti-aging and air tightness;
b. The built-in pressure differential sensor and pressure differential controller accurately set the desired pressure difference value, allow the valve to react quickly when the ambient pressure difference deviates from the set pressure difference value, and completes the air volume adjustment in 3 seconds to achieve the established system pressure difference.
c. The variable air volume control valve has a operating temperature range of 10 to 50 degrees C, a pipe pressure difference of 20 to 1500Pa, and can be installed horizontally or vertically without position restrictions.
d. The products supplied must be subject to strict airflow testing and parameter calibration before they are manufactured, and the control accuracy of the products should be 5% ±.
e. The variable air valve applied to the exhaust cabinet shall be corrosion-proof spraying, the valve control response time of 1 second, the balancing time of 3 seconds, and the wind speed of the exhaust cabinet surface shall be controlled within the range of ±20% of the set value.
f. The variable air valve on the exhaust cabinet has the function of monitoring the operation of the ventilation cabinet, in the event of abnormal ventilation system, the alarm is immediately raised, and according to the emergency button state set next to the ventilation cabinet, the air discharge of a ventilation cabinet is immediately opened to a large to cope with the emergency situation.
g. Variable air volume valve should be pressure-independent air volume control, to ensure that the system of multiple laboratories or multiple ventilation cabinets running at the same time, their independent adjustment, mutual interference;
b. The valve body and accessories are made of galvanized steel plate, the thickness of galvanized steel plate is not less than 0.6mm, should have good mechanical processing performance, should avoid the parts in the bending, rolling molding process to destroy the surface galvanized layer.
welding method should be adopted by welding measures; c. the rolling roundness of the valve body should be as high as possible to ensure the air tightness of the valve; d. Bearings should meet the requirements of corrosion resistance, wear resistance, anti-aging and air tightness; e. large pressure capacity is not less than 1500Pa; f. normal operating temperature is 10-50 degrees C; g. valve body is sprayed, the valve plate with stainless steel material, has met the corrosive environment.
h. Selection of Well-known, technically mature executive agencies in Europe and the United States, to ensure that the number of motor shutdowns not less than 60,000 times, maintenance-free.
editor: Sever Safety