The pump is a mechanical device. If you want to formulate a pump specification for the factory, you need to gather the knowledge of engineers such as process, machinery, instrumentation, etc. This article hopes to make a simple introduction to increase the understanding of the pump, based on the structural characteristics of the pump itself and the original 理Provide reference for pump specifications.

　　Basic energy required by the pump itself

　　 – suck up and push up 

　　• Classified according to the original  structure

　　– A. Centrifugal pump—Use centrifugal  to convert speed  energy into pressure  energy pumps

　　• 1. Scroll pump 2. Turbine pump (multi-stage scroll pump)

　　 – B. Rotary propeller pump— The speed of the fluid passing through the impeller

　　• 1. Axial flow pump 2. Diagonal flow pump

　　 – C. Move the pump toward -the volume changes to generate pressure 

　　• 1. Live pump 2. Column pump

　　-D. Rotary pump- squeeze the space between the rotors to generate pressure 

　　• 1. Gear pump 2.  Rotary pump

　　 – E. Other pumps

　　• 1. Jet pump 2. Bubble pump 3. Viscous pump

　　 In use, centrifugal pumps have dry advantages such as: small fluid pulsation, simple structure, variety of fluids that can be transported, and wide pressure range. Therefore, most liquid pumps used in piping systems are centrifugal, but 

　　Select a suitable centrifugal pump instructions  several elements:

　　– 1. Liquid properties 2. Water  3. Head 4. Speed ​​5. Site restrictions

　　• Consider the nature of the liquid as follows:

　　 – Wen 

• Inlet system-for normal temperature water, the pump can suck up 10.33m under absolute vacuum. The higher the temperature  is, the higher the suction energy  decreases. In general, the actual temperature is about 6m at normal temperature. When the temperature  reaches 85℃, it needs to be changed to Positive pressure, so the pump suction energy above the temperature  is almost zero.

　　• Pump casing type-when the fluid temperature  is above 150 ℃, the center support pump is required. Due to the high temperature operation, the pump  is thermally expanded due to the material. The center support pump casing can expand upward and downward to avoid jamming with the impeller.

　　 – Sticky 

　　• When the centrifugal pump delivers high-viscosity  liquid, it will produce head, efficiency  low, horse increase and other phenomena. When the viscosity of the conveying fluid is greater than 2000cp, a gear pump or a column pump should be used.

　　 – Specific gravity

　　• The specific gravity of the conveying fluid directly affects the shaft 力 and outlet pressure力 of the pump, so the specific gravity of the conveying fluid needs to be investigated to avoid the occurrence of overload or outlet pressure and other phenomena.

　　 – pH value

　　• The material of the pump is cast iron, copper, cast steel,  rust steel series, etc. Transport fluid will cause chemical changes to the genus , and other special combinations  should be considered to increase the service life of the pump.

　　 – fluid particles  containing 

　　• Most centrifugal pump impellers mostly use the closed type, because of its stable operating range and good efficiency , When the conveying fluid contains solid suspended solids, an open impeller should be used to avoid obstruction .

　　Closed impeller Open impeller

　　• Outlet(Stream)

　　-Volume of liquid delivered per unit time

　　 – Common units are: m3/min, GPM, l/s, CMS

　　• 1 m3/min = 264.192 GPM

　　• 1 CMS = 60 m3/min

　　 – Pump outlet water  greater than 15m3/min It is recommended to use double suction impeller, the pump axial push  can achieve balance and extend bearing life.

　　•Head

　　 – The centrifugal water pump is a non-fixed water pump, and its water output and shaft horse  vary greatly with the change of head. Generally, when the head is below 8M and the water output is very large, axial or diagonal flow pumps are used. When the head is below 90M, a single-stage impeller is used, and when it is above, a multi-stage impeller pump is used. Single-stage impeller Multi-stage impeller pump

　　• Pump speed

　　 – Generally, the water pump is driven by a motor, and the motor speed directly affects the performance of the water pump.

　　-The speed of the speed has the following considerations:

　　• Related matters Fast speed Slow speed

　　•Water pump size is smaller larger

　　•Water pump price lower higher

　　• Shorter pump life longer

　　• NPSHr higher lower

　　• Piece wear faster faster

　　• Venue restrictions

　　 – General pumps are tested horizontally. The following table shows their advantages:

　　– Horizontal pump

　　• 1. The main  parts have less corrosion above the water surface.

　　• 2.Piece replacement repair capacity.

　　• 3. The price is lower.

　　–  type pump

　　• 1. Small installation area.

　　• 2. No water is needed when starting.

　　• 3. Motor position is high  immersed in water.