Exhaust air modification system for laboratory decoration

In the process of chemical experiments, some harmful gases are not discharged outdoors in time, which can easily cause indoor air pollution, affect the health and safety of laboratory personnel, and also affect the accuracy and service life
of instruments and equipment.

PATEO Xiaobian takes everyone to understand the relevant knowledge
of the exhaust air transformation system in the laboratory decoration.

First, the laboratory exhaust ventilation transformation design parameters laboratory ventilation transformation design parameters include indoor and outdoor temperature and humidity requirements; Air quality; Equipment and process heat loads, including sensible and latent heat; Expected increase in internal loads; Minimum number of air changes; Intake and upwind; Exhaust equipment type; Control and alarm; Adjustment of the size and number of fume hoods is possible; Room pressure difference; Backup
of devices and power supplies.

1.
The ventilation system uses terminal noise ≤62db
.

2.
The wind speed in the branch pipeline is 6~8m/s, and the wind speed in the main pipeline is 8~14m/s
.

3.
Number of ventilation: The number of ventilation in general chemistry laboratories is 8 to 12 times / hour
.

4.
The fan adopts corrosion-resistant FRP centrifugal fan, and the system adopts frequency conversion control to achieve the purpose of
energy saving and noise reduction.

5.
Ventilation equipment design air volume: ventilation hood surface air speed: 0.
3 ~ 0.
8 m / s, fume hood design air volume of 1800m3 / h, universal exhaust hood surface wind speed: ≥0.
35 m / s, universal exhaust hood exhaust air volume of 150 ~ 350 m3 / h, atomic absorption cover surface wind speed: ≥ 0.
35 m / s, exhaust air volume 350 ~ 600 m3 / h
.

Second, the laboratory exhaust system control steps and schemes 1, the laboratory according to the process requirements and functional layout to select a certain number of fume hoods, some also have part of the local exhaust hood
.

Usually the number of ventilation is much greater than 10 times, generally more than 20-30 times, to meet the requirements
of the number of air changes.

The ventilation volume and number of ventilation should also be checked for the minimum opening area of the fume hood, and if it is less than the number of ventilation required, the integrated exhaust system
should be added.

2.
The laboratory ventilation adopts a new air system, and the exhaust of the fume hood is not circulated indoors
.

Since the laboratory requires the room to be negatively pressurized relative to other auxiliary areas
.

Therefore, the fresh air volume of the laboratory is designed to be 70%-80%
of the exhaust air volume.

In addition, 20%-30% of the fresh air is sent to the auxiliary room of the laboratory, office, management room, inner walkway, etc.
, and then supplemented to the room
by the gap between the doors and windows.

The air volume balance of the laboratory fume hood can be controlled by means of a constant air volume control system, that is, the exhaust air volume is constant, and the supply air volume and the gap between the doors and windows are constant
.

This method is suitable for laboratories where the maximum exhaust air volume meets the minimum number of air changes
.

3, for the exhaust air volume is much greater than the minimum ventilation requirements of the room can also use a two-stage ventilation control system to ensure the balance of air volume, that is, according to the displacement signal of the fume hood, the exhaust fan, the blower has 2 kinds of supply air conditions, low air volume working conditions should be used to maintain the minimum number of air changes requirements, saving energy consumption
.

In this case, a variable air volume control system
is used.

When the air volume of the fume hood changes, the exhaust air volume will also become relatively small, and the exhaust fan placed on the roof is required to change the frequency with the change of the position of the fume hood door, reduce the air volume, and ensure that the wind speed of the fume hood surface is constant
.

Third, laboratory gas emission treatment 1, under normal circumstances: acid gas selection vertical acid fog tower; Toxic and organic gases are selected from optical catalytic purification chambers
.

The two types of equipment are installed at the end of the exhaust system, the vertical acid mist tower is installed in the positive pressure section of the fan, and the optical catalytic purification box is installed in the negative pressure section of the
fan.

After the gas in the animal room is filtered in the initial and intermediate effects, it is directly discharged into the atmosphere, but the high-pressure jet stream is treated at the exhaust port, and the spray height is more than
3 meters.

2, laboratory ventilation system transformation is a comprehensive work, we must pay attention to this work when doing this work, do not look at this problem alone, because only one part of the problem to solve the effect of the entire system transformation is not obvious, so it is still necessary to comprehensively transform and improve
.