There are three types of Photo etching: HME, mechanical and electrostatic. We'll explain each of them in a simplified way:
HME is the acronym for Heat and Moisture Exchanger in Portuguese exchanger heat and humidity. It usually works as an “artificial nose”, a passive humidifier. It captures the exhaled heat and moisture and uses it to warm and humidify the next inhalation. Most HME filters do not add heat or water to the system.
A typical HME is a passive humidifier because it captures heat and moisture from the expired gas and returns up to 70% to the patient on the next inspiration. Like Photo etching, there are three types of HME filters: Hydrophobic, Hygroscopic and Mixed (hydrophobic and hygroscopic). Discover some of our equipment commonin the best reference centers in the country and the world.
It features pleats of a ceramic fiber element, which repels water with a large surface area and low conductivity. Instead of absorbing water, it prevents its passage to the external environment. Inspired gas is humidified and heated with water held during expiration on the inner surface. Its surface area is increased by several folds and has greater internal volume and greater resistance.
Hydrophobic HME, ventilation filter consists of layers of material with low thermal conductivity (paper or foam), which may or may not be impregnated with hygroscopic salts – calcium or lithium chloride. As the patient exhales warm, moist air, the membrane captures heat and moisture in the form of condensation. When the patient inhales, the HME returns heat and moisture from the inspired gas.
In this filter, after the hygroscopic membrane, there is a fully hydrophobic electrostatic filtering membrane. In other words, as it is a passive method, there is a low probability of condensate production, and the addition of the hydrophobic membrane eliminates the probability of passing condensate to the circuit. Photo etching is very helpful in preventing nosocomial infections.
HEPA stands for High Efficiency Particulate Air, which are air filters with high efficiency in separating particles. Discover some of our equipment common in the best reference centers in the country and the world. Typical mechanical filtration uses a randomly oriented fiber layer material with no controlled diameter. Filters capture and retain these particles in three different mechanical ways:
Particles smaller than 1 and larger than 0.3 µM: Due to their mass, particles get trapped in deeper parts of the filter and follow a path that brings them into contact with the fibers in the middle of the filter. The airflow around is smaller than the radius of the particle causing its capture.
Particles smaller than 0.3 µM: These particles move erratically, which shocks the fibers. Diffusion is the most difficult air filtering mechanism to imagine or explain. Very small particles come into contact with fibers due to diffusion effects.
The Photo etching material consists of a mesh of hydrophobic polypropylene fibers called Electret Split Fibers. The membrane passes through an electrical energy field during manufacturing. With the same methods, electrostatic filters use different mechanisms to capture or retain particles. It has ability to trap particles and microorganisms, while offering low resistance to airflow.
The choice of Photo etching for the mechanical fan is always important, but during the COVID-19 pandemic it became an even more crucial factor. The technical specifications of the different filters must be taken into account, as well as the effectiveness against viral transmission.
The sizing of the bag filter must follow some requirements, based on the shape of the filtering element and on the particle size distribution of the particulate material generated in the industrial process. One of the fundamental parameters to know how to dimension the equipment is the cloth-air ratio also called filtration speed.
We know that dimensioning is the filtering area of industrial equipment. Therefore, the Photo etching, accompanied by the pulsating jet cleaning system, is the equipment that requires the smallest filtering area.
With these specifications, it is possible to define the filtration ratio (number of bags needed) and the dimensions of the filter. This means that the correct dimensioning comes with the result gets by the technical analysis: the ratio of the flow by the total filtering area of the equipment bags.
In a hypothetical situation, considering an industrial environment, let's imagine that the ventilation filter receive the dirty gas in the amount of 60,000 m3/h (cubic meters per hour), keeping the space of 1,000 m2 (square meters) of total filtering area. With this, your filtration rate will result in a total of 1 m3/ (m2.min).
It is important to point out that we do not state here whether this is the best rate, as it varies from case to case. This filtration speed influences the periodic cleaning that must carry out on the equipment. It helps to avoid clogging of the filtering element. For this reason, the ventilation filter type filter with an automatic cleaning system is the most recommended for all industrial processes.
The air-to-cloth ratio is the speed at which the gas generated in the industrial process passes through the filtering element. This filtration speed directly links to the particle size of the pollutants, the input concentration of the powder, the bag cleaning system and the gas temperature.
These parameters are essential for specialized engineering to carry out an efficient design for your company's ventilation filter. With this technical information, it is possible to determine the size of the bag filter and even the initial cost of your project. It will enable your company to achieve maximum efficiency with the application of filtering equipment.
