How to choose the right asphalt pump?

First, the selection of asphalt pump in the specific choice, from the following aspects: (1) the shape of the valve spool is mainly based on the selected flow characteristics and unbalanced forces and other factors to consider. (2) Wear resistance When the fluid medium is a suspension containing high concentration of abrasive particles, the valve core, the valve seat joint surface will be severely rubbed each time it is closed. Therefore, the flow of the valve should be smooth, the valve's internal material to be hard. (3) Corrosion resistance Due to the corrosive medium, try to choose a simple structure of the valve in the case of regulatory function. (4) Medium temperature, pressure When the medium temperature, high pressure and changes, should use the valve core and valve seat material by temperature, pressure changes in small valves. (5) to prevent flash and cavitation flash and cavitation only produce liquid medium. In the actual production process, flash and cavitation not only affect the calculation of flow coefficient, but also the formation of vibration and noise, so that the valve life is shorter, so the valve should be selected to prevent flash and cavitation. Second, the overview of asphalt pump: Asphalt pump by the implementing agencies and valves. The use of compressed air as the power source, for a variety of corrosive liquids, with particles of liquid, high viscosity, volatile, flammable, highly toxic liquid can be smoked exhausted. Suitable for placement in a variety of special occasions, used to pump the kind of conventional pump can not suction medium. Asphalt pump actuator with pneumatic actuator and electric actuator, respectively, type QBY pneumatic asphalt pump and DBY electric asphalt pump. Asphalt pump body (body) material has four kinds: plastic, aluminum, cast iron, stainless steel, respectively, according to the requirements of liquid or gas medium selection. Asphalt pump internal diaphragm is also based on different liquid media were nitrile rubber, neoprene, Viton, polyvinylidene fluoride, polyhexachlorethylene, so when ordering to specify the type of media. Third, the specific selection of asphalt pump: 1, the role of asphalt pump Asphalt pump selection of the role of the method is only used in the selection of pneumatic actuators only, and its role in the positive and negative through the implementing agencies and the positive and negative valve action combination . There are four types of combination that is positive (air-off type), positive and negative (air-type), anyway (air-type), anti-anti (anti-off type) Open and Qi off two. For the choice of asphalt pump mode of action, mainly from three aspects: (1) process safety; (2) the characteristics of the media; (3) to ensure product quality, economic loss is minimal. 2, asphalt pump flow characteristics of choice

PassiveInfrared Ray

It is mainly made of a material with high pyroelectric coefficient, such as lead zirconate titanate ceramics, lithium tantalate, triglyceride titanium sulfate, etc. to make the detection element with a size of 2*1mm. Install one or two detection elements in each detector, and connect the two detection elements in series with reverse polarity to suppress the interference caused by the rise of their own temperature. The detection element converts the detected and received infrared radiation into a weak voltage signal, which is amplified by the field effect tube installed in the probe and output outward. In order to improve the detection sensitivity of the detector and increase the detection distance, a Fresnel lens is generally installed in front of the detector. The lens is made of transparent plastic. The upper and lower parts of the lens are divided into several equal parts. It is a kind of lens with a special optical system. It can amplify the signal by more than 70 decibels in cooperation with the amplifying circuit, so that the movement of people within 20 meters can be measured.
The Fresnel lens uses the special optical principle of the lens to produce an alternating "blind zone" and "high-sensitivity zone" in front of the detector to improve its detection and reception sensitivity. When someone walks in front of the lens, the infrared rays emitted by the human body will alternate from the "blind area" to the "high sensitive area", so that the received infrared signal is input in the form of sudden strong and weak pulses, thereby strengthening its energy amplitude .
The central wavelength of infrared radiation radiated by the human body is 9~10--um, and the wavelength sensitivity of the detection element is almost stable in the range of 0.2~20--um. A window equipped with a filter lens is opened at the top of the sensor. The wavelength range of light that this filter can pass is 7~10--um, which is suitable for the detection of human infrared radiation, and other wavelengths of infrared rays are filtered. The sheet is absorbed, thus forming an infrared sensor specially used to detect human body radiation.

PassiveInfrared Ray,Pyroelectric sensor,Highly sensitive sensor

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