The weighing cover is also called negative pressure weighing cover or weighing room (working principle). The weighing cover is also called negative pressure weighing cover or weighing room. It mainly includes negative pressure weighing cover and activated carbon weighing cover. The negative pressure weighing cover is mainly used for local purification equipment in pharmaceutical, microbial research and scientific experiments, The activated carbon weighing cover is mainly used for the local purification equipment of activated carbon weighing in the water needle workshop. The weighing cover can provide a vertical unidirectional air flow, Part of the clean air circulates in the working area, and part of it is discharged to the nearby area, which makes the working area produce negative pressure and prevent cross pollution. It can control the dust and dust in the working area from spreading to the outside of the operation area, so as to ensure the high cleanliness environment of the working area.

The weighing operation area is protected by 100 level vertical laminar flow ISO 5 (NF, en, iso14644-1), and designed according to the requirements of FDA, EU GMP and Chinese GMP.

Working principle of weighing cover:
The air in the weighing room is pressed into the static pressure box by the centrifugal fan through the primary effect filter and the medium efficiency filter. After passing through the filter, the clean air is blown out from the air outlet side of the air diffusion air supply unit. The clean air flows through the working area with uniform cross-section wind speed, thus forming a highly clean working environment. The operation area of the central weighing cover is maintained in a negative pressure state, and 10% of the circulating air is discharged. The air in the central weighing chamber is self circulated through a three-stage filtration system (the filter removes 99.99% of the dust with particles ≥ 0.3 μ m) and the design meets the GMP requirements of pharmaceutical companies.

Purpose of weighing cover:
The dust and reagent can be weighed and sub packed in the weighing cover equipment, which can control the overflow and rising of dust and reagent, prevent the inhalation hazard of dust and reagent to human body, and avoid the cross pollution of dust and reagent, and protect the external environment and the safety of indoor personnel

Weighing cover structure:
The weighing cover is made of 304 stainless steel, and the wall panel in the working area is made of 304 stainless steel (1.2mm thick, oil drawing short wire), and the inner arc angle of the wall panel is connected without dead angle, so as to ensure the sealing, tidiness and beauty of the working area.

The negative pressure weighing cover adopts modular design, which is easy to assemble and disassemble on site. It is composed of middle efficiency, fan box filter and uniform flow membrane.
The weighing cover is composed of working area, return air box, fan box, outlet box and outer box. The control panel is located in the front of the internal working area of the equipment. The control panel adopts Siemens touch screen inverter control system, which can control the start and stop of the fan, adjust the frequency of the fan, and adjust the wind speed required in the working area (after the equipment is installed and used, the frequency needs to be adjusted by special personnel).

Weigh the cover and display the pressure difference, wind speed, temperature and humidity of the primary filter, medium efficiency filter, filter and flow sharing membrane. In addition, the dust particle monitoring system is configured to monitor the dynamic cleanliness in real time, which plays a reference role in cleanliness. At the same time, it also gives alarm for abnormal wind speed, pressure difference and cleanliness. The differential pressure gauge is used to measure the pressure of the filter at different times, providing a lasting performance indication for the weighing cover.

The initial effect should be cleaned regularly according to the usage. Four differential pressure sensors are installed in the return air duct, corresponding to the resistance of the special flow sharing membrane, primary, middle and filter, and displayed in the touch screen. When the pressure difference of the filter exceeds the range, there is an alarm on the touch screen and a sound alarm on the automatic control box.

Optional functions of weighing cover / weighing room:
The distribution cabinet is set separately;
LCD / touch screen control;
It has low wind speed alarm, over pressure difference, over temperature and humidity alarm function;
With USB interface, the data can be exported and printed;
Increase temperature and humidity adjustment function to adjust temperature and humidity;
Equipped with dust particles, planktonic bacteria detection function;
PLC control system, wind speed automatic constant, with wind speed, differential pressure, temperature and humidity display;
Product model of weighing cover / weighing room (gzzj-cs1200)
External dimension (mm): w1300xl1500xh2450;
Internal dimension (mm): w1200xl1000xh1950;
Overall material of outer box: SUS304 stainless steel plate;
Filter: aluminum frame liquid tank filter h14, 1220 * 610 * 69mm;;
Purification grade: Class 100@0.5UM ;
Control mode: manual switch control / touch screen automatic control;
Rated wind speed: 0.36-0.51m/s (GMP standard);
Cleanliness level: 100;
Rated power: 0.65kw;
Average illumination: 400lux;
Imported frequency converter: speed regulation (frequency regulation);
Protection objects of weighing cover / weighing room:
Protective drugs
Protection of operators
protect the environment
Note: non standard products can be made according to customer requirements.
Optional accessories: 1. Wind speed sensor; 2. Differential pressure sensor; 3. Frequency converter; 4. Touch screen; 5. PLC control; 6. Polymer current sharing film.