The basic requirements for a successful pump device are performance and life. The performance is the pump parameters: lift, flow and efficiency. Life is the total number of hours that must be replaced by one or more parts before the permissible performance is maintained. It is mainly a measure of resistance to corrosion, erosion, or the two combinations of structural materials under actual operating conditions.
When selecting materials for pump flow parts, the factors to be considered are user experience, expected pump life (for short or long term), intermittent or continuous use, pumping harmful or toxic liquids or liquids. Corrosive liquids vary from one or more of the following: temperature, concentration, purity, speed, in solid and gas.
Stainless steel usually refers to an iron based corrosion resistant alloy with a chromium content of 12~30%. The corrosion resistance of stainless steel is mainly determined by the presence of chromium, iron chromium stainless steel based system is two yuan. The addition of other alloy elements can affect and change the microstructure and properties of the alloy. Stainless steel chemical pump
According to the different carbon content, 18% chromium stainless steel can be divided into 3 types. That is, ferrite steel with less than 0.08% carbon, austenite &mdash of 0.08~0.22% carbon, ferrite steel and austenitic steel more than 0.22% carbon.
When choosing the pump material, the long one pump industry mainly takes into account the following key points:
(1) the corrosion of media: the corrosion resistance of materials to medium is in a certain range, for example, 1Cr18Ni9 is resistant to corrosion of nitric acid or organic acid with moderate and dilute concentration, but it is not resistant to dilute sulfuric acid and hydrochloric acid corrosion.
(2) electrochemical corrosion: the same metal material is best used in the whole flow channel of the pump.
(3) the temperature of the medium: the material is brittle at very low temperature, and it will creeping at high temperature. A certain material can resist the corrosion of some medium at room temperature, but it does not necessarily corrode the high temperature medium. Therefore, the material performance should meet the temperature requirement of the conveying medium.
(4) economy: the price and machinability of materials are different. Therefore, when several materials meet the requirements of corrosion and temperature, we should choose materials that are relatively inexpensive and have good machinability.
(5) wear properties of solid particles: wear resistant materials should be used when solid particles are contained in the medium.
(6) bite between materials: for the relative movement of the parts, such as bushings, bolts and nuts, impeller sealing ring and a pump sealing ring, in the choice of materials should be two parts material hardness of some differences, or in handling and operation each other easily bite or scratch.
(7) the size difference of the same part: when in the same part of the larger temperature difference, such as in the transport of high temperature liquid cooling pump cover, the pump cover and the medium contact temperature at high expansion, and the cooling water temperature at the contact of low expansion, this part should use plastic materials so, in operation due to different crack expansion.
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