The fresh air system is a set of independent air treatment system composed of air supply system and exhaust system, which is divided into two types: the pipeline fresh air system and the non pipeline fresh air system. The pipeline type fresh air system is composed of fresh air fan and pipe fittings. The outdoor air is purified by the fresh air fan and led into the room, and the indoor air is discharged by the pipe; the ductless fresh air system is composed of the fresh air fan, and the outdoor air is also purified by the fresh air fan and led into the room. Relatively speaking, the ducted fresh air system is more suitable for industrial or large-area office area due to large quantities of work, while the ductless fresh air system is more suitable for home use due to its convenient installation.
Fresh air plays a very important role in the operation of the air conditioning system, especially in the clean air conditioning system, there are no windows connected with the outside in each room in the clean area, the size of the fresh air will directly affect the comfort of the indoor staff, and the quality of the fresh air determines the cleanliness of each room in the clean area.
The clean operating department is not as large and large as the industrial clean room, and its functional areas are relatively concentrated and concise. It can only be divided into clean area, buffer area and common area. The control rooms of the clean operation Department are relatively scattered with small area, small volume and complex functions. The process has strict requirements on the cleaning and pollution of people, objects and objects. The relevant functional areas are required to be complete and arranged reasonably. At the same time, they should meet the requirements of infection control management of the medical and health departments. It is often divided into super clean area, clean area, clean area, buffer area, common area, pollution area, auxiliary function area and other areas.
The following is a brief introduction of several fresh air treatment forms of the clean operation Department.
I. tertiary filtration of fresh air
Fresh air is an important factor to ensure that the clean air-conditioning system is free from outdoor pollution. If the concentration of new wind dust entering the system is high, it will quickly block the components in the system (especially the high-efficiency filter at the end), so that the fresh air volume will be sharply reduced, the proportion of indoor oxygen will be reduced, and the vicious cycle will be caused. Therefore, for the treatment requirements of fresh air, GB50333-2002 "technical code for building of clean operation Department of hospital" puts forward a concept, namely, the concept of three-level fresh air filtration: "in the first level of fresh air filtration in the system, coarse effect filter with the counting efficiency of no less than 50% for particles with the counting efficiency of no less than 5 μ m, medium effect filter with the counting efficiency of no less than 50% for particles with the counting efficiency of no less than 1 μ m and The combination of three-stage filters for sub high efficiency filters with the counting efficiency of ≥ 0.5 μ m atmospheric dust not less than 95%. "

The first level of filtration here refers to the filtration of fresh air dust. The filter at the fresh air outlet adopts the form of three-level combination, that is, the three-level filtration of fresh air. After three-stage fresh air filtration, for the operating room with high efficiency filter as the last stage, its comprehensive effect will reduce the air dust concentration into the fresh air system by one order of magnitude. Meanwhile, after three-stage fresh air filtration, for the operating room with high efficiency filter as the last stage, its comprehensive effect will reduce the air dust concentration into the fresh air system by one order of magnitude. Meanwhile, for the surface cooler and medium efficiency The service life of filter and high efficiency filter will be more than three times longer than that of traditional fresh air filter, and its economic effect is considerable.

II. Form of fresh air system
For clean air conditioning, its air treatment generally adopts combined air conditioning unit. In addition to the first level of three-level fresh air filtration, a medium efficiency filter shall be set in the combined air conditioning unit, and a high efficiency filter shall be set at the end. The fresh air can be divided into the form of self collecting fresh air and centralized fresh air. Self collecting fresh air means that the fresh air of each air conditioning system is not treated, directly mixed with the return air, and then After the heat and humidity treatment in the unit is sent to the operating room, colleagues may have questions about why the fresh air three-stage filter unit is set up separately, and there are only fans and three-stage filters in the unit. Why not set the three-stage filter in the unit, so that one fan can not be saved?
The first reason is that the air supply fan in the combined air conditioning unit needs to overcome the resistance of the unit's own equipment, as well as the resistance of the air duct, valve and the end high efficiency filter. If the three-stage fresh air filtration is added, the pressure head of the air supply fan will be very high, and the working point of the fan will be unstable. Second, the fresh air volume of the general clean air conditioning system accounts for 10% - 15% of the total air volume. The area of the fresh air outlet on the combined air conditioning unit is small. If the three-stage filter is installed in the combined air conditioning unit, the area of the fresh air passing through the filter is small, and the filtering efficiency will be reduced accordingly. Therefore, it is obviously necessary to set up a separate fresh air filter unit.
III. another form of fresh air treatment - centralized fresh air
It refers to that the fresh air of all air conditioning systems is uniformly filtered and heat treated by the fresh air unit, and then the fresh air is distributed according to the needs of each system. The centralized fresh air system adds heat and cold treatment at the fresh air unit compared with the self collected fresh air system. For the status point of the fresh air treatment, the specification stipulates that when the clean operation Department is equipped with another centralized fresh air treatment system, the fresh air treatment unit It shall be able to handle the fresh air to the enthalpy value not greater than the required indoor air state point in the cooling season. In other words, the fresh air should bear part of the indoor heat and humidity load, and the more it bears, the better.
IV. the features of the independent fresh air treatment system in the clean operating room are as follows
(1) the whole clean operating department is composed of an independent fresh air system and the operation between the purification air conditioning unit and the exhaust unit in each clean operating room.
(2) the fresh air branch pipe of the fresh air system is connected (inserted) to the air supply pipe of the purification air conditioning unit in the clean operating room, or directly connected to the automatic air supply shut-off plenum. A two position control constant air volume device is arranged on each fresh air branch pipe.
(3) one way valve shall be installed on the air supply pipe of purification air conditioning unit to prevent backflow in case of single fresh air supply. Each operating room is equipped with an exhaust unit with independent exhaust, and the exhaust air volume of the exhaust fan can be controlled by the regulating valve.
(4) the independent fresh air system not only bears the positive pressure air volume of each clean operating room, but also bears the normal fresh air volume. Each operating room's independent air conditioning unit becomes a circulating unit, which only controls the indoor temperature and humidity. The exhaust fan exhausts the indoor pollution gas and peculiar smell.
Five, summary
The design and practical operation of clean operating rooms in China show that it is appropriate to determine the fresh air volume according to the minimum fresh air volume and air change times required for personnel breathing, the fresh air volume to maintain the positive pressure value of the room and the large value of the fresh air volume corresponding to the required purification level of the room, which is also consistent with the values of most countries in the world. If only from the point of view of the relationship between the value of fresh air volume and the system in the operating room, the fresh air volume in the room should be appropriately increased to meet the requirements of winter and transitional air conditioning for the clean operating department with large heat output and high requirements for indoor temperature and humidity, such as the use of two pipe system. At this time, the amount of fresh air needed to eliminate indoor waste heat is about 1500 ~ 1600m3 / h. Therefore, it is allowed to increase the amount of fresh air properly, otherwise, it is necessary to add an independent heat pump system to cool the fresh air separately or adopt a four pipe system, which not only consumes energy but also increases the cost.
From the point of view of meeting the requirements of indoor temperature and humidity, and the relationship between control accuracy and response time, the four pipe system is more suitable for the air conditioning system in the operating room of the hospital.
Shandong ed purification Engineering Co., Ltd. is a professional hospital clean operating room, ICU, disinfection supply room, blood purification center, vein distribution center, disease control center, digital integrated operating room, intervention operating room, positive and negative pressure operating room, radiation protection, obstetrics, infant ward, burn ward, hemodialysis room, laboratory, pathology department, plastic surgery room The business scope of such high-tech enterprises as purification engineering mainly covers the design and construction of Medical Building Decoration Engineering, central air conditioning engineering, electrical engineering, intelligent engineering, water supply and drainage engineering, gas engineering, etc. The company integrates professional scheme design team, complete supporting product channels, professional system construction team and perfect after-sales service. With the relevant construction qualification issued by the national construction department; with an experienced engineering technology research and development team; with years of professional accumulation in the field of purification, combined with the construction management practice of many domestic projects, to provide comprehensive and high-quality overall purification system technical support for domestic customers. If you want to know more about the workshop purification construction, please contact the engineering personnel of the project department in detail. For more knowledge of medical purification industry, please pay attention to wechat public number: aide-188 (ED purification oxygen supply)