The epidemic has introduced us to many new terms related to diseases.
This epidemic has made us recognize many new terms related to diseases, and "negative pressure ambulance" was a hot topic two days ago. In order to understand this kind of ambulance more comprehensively and concretely, we asked the engineer of SAIC Datsun who is responsible for the research and development of negative pressure ambulance.
First of all, what is a "negative pressure ambulance" and what is the difference between it and an ordinary ambulance? Ambulance A, B, C three types, A-type is a transfer ambulance, with basic first aid and nursing equipment; B-type is a first aid vehicle, in the A-type on the basis of a lot of first aid equipment, such as pressurized infusion equipment, chest decompression equipment, respiratory machines, defibrillators and so on. The negative pressure ambulance is of type C, mainly used to transport patients with high-risk infectious diseases, especially those that can be transmitted through the air, in addition to this outbreak of the new coronavirus, as well as influenza, typhoid fever and so on.
Negative-pressure ambulances and the other two types of ambulances is the biggest difference between the "negative pressure" on top of the word, simply put, so that the air pressure inside the car is lower than the outside air pressure, air is always from the high pressure to the pressure of the low pressure of the place where the flow, which ensures that the virus inside the car will not be contaminated with the outside world.
In fact, the principle of "negative pressure" is very simple, and is often seen and used in our daily lives. For example, if we use a straw to drink water, inhaling will create a low-pressure area inside the straw, and then the outside air pressure will press the water into our mouths. Another example is the formation of a typhoon, the eye of the wind is a low-pressure area, so the surrounding air is moving toward the eye, and the size of the wind depends on the size of the pressure difference.
For a negative-pressure ambulance you can think of it as a miniature eye of the storm, where the outside air is only sucked in and the air inside the vehicle never runs out. Negative pressure ambulance is able to generate negative pressure is dependent on the negative pressure generator to complete, can be understood as a pump, constantly will be the vehicle air network outside. Of course, the air is not discharged directly to the outside of the vehicle, but will go through a filtration system, which is a bit like an air purifier at home, except that the standards are much more stringent.
National Ministry of Health on the negative pressure ambulance exhaust system filtration standard is, 0.3 micron particle diameter particles above the filtration efficiency of 99.97%, as a comparison of the diameter of PM2.5 particles is 2.5 microns, the negative pressure ambulance standards to enhance the nearly an order of magnitude. And SAIC Datsun engineers told me that their V80 negative pressure ambulance filtration efficiency is even higher, reaching 99.997%.
In addition to the negative-pressure generator, there is also a set of ventilation equipment responsible for delivering fresh air to the vehicle, and this system also has a purification function to ensure that the air inside the vehicle is clean. Datsun V80 negative pressure ambulance through the negative pressure device, ozone generator and ultraviolet irradiation lamp to sterilize.
There will be a certain difference between the exhaust air and the air supply equipment, and the national standard is between 10Pa and 30Pa. The design, the air supply system is located in the top of the compartment, the exhaust system in the bottom of the compartment, the air flow inside the car is from top to bottom. The advantage of this design is that the patient is lying down in a lower position, while the medical staff is generally sitting or standing in a higher position, always keep clean air above can better protect the medical staff.
There is one final piece of equipment -- the isolation chamber. It's like a large capsule that encases the patient, and like the ambulance, it has air filtration to ensure that virus/microbe-contaminated air doesn't escape. It's another layer of insurance, and with these multiple layers of protection, it can be said that the spread of the virus is completely blocked. That's why negative-pressure ambulances play such an important role in this outbreak, and many domestic automakers, including SAIC Datsun, are expediting production of these ambulances.
The next question is how difficult is it to design and produce such a negative-pressure ambulance? I thought it would be just like any other ambulance, with medical equipment placed on the vehicle according to standards, but after talking to Datsun engineers, I realized it's not that simple.
One of the biggest problems with producing a negative-pressure ambulance is improving the seal. Taking the previous example of the straw, if the straw has a hole in it, it becomes very difficult or even impossible to drink from it. Because that hole will make the pressure difference between the inside and outside of the straw become smaller or disappear, the same reason, if the vehicle sealing is not good, even if there is a negative pressure generator is working, still can not reach the negative pressure environment.
Taking the Datsun V80 negative pressure ambulance as an example, its sealing is upgraded by 50% relative to the normal model. Such a big improvement requires the entire vehicle's interior to be redesigned, and seams that previously seemed inconsequential are now not allowed to exist. In addition, the mounting holes and maintenance holes reserved on the regular version have to be sealed, and the related wiring needs to be altered. These seemingly simple things require a lot of investment for the car companies.
First is the cost, V80 negative pressure ambulance than ordinary models alone procurement costs increased by 50%; second is the time, these changes need workers to complete manually, so the normal production of a Datsun V80 negative pressure ambulance cycle is double that of the ordinary models, about 30 days. But in the face of this battle with the virus, time is running out and everyone is scrambling for time. on January 24th, SAIC Datsun received a production task from the Ministry of Industry and Information Technology, and asked for the delivery on February 5th; so Datsun resumed the work urgently, and started 240 hours of uninterrupted production from the first day of the Chinese New Year, and the first batch of negative pressure ambulances were delivered smoothly.
Not only Datsun, but also many automobile companies and other manufacturing industries have been involved in this epidemic, delivering ammunition to the frontline troops. In the end, we hope the epidemic will end sooner rather than later, so let's go Wuhan.
This article comes from the author of the automobile home car, does not represent the views of the automobile home position.