Technology inquiry
A pump is a device used to move liquids or slurries.
A pump moves liquids from lower pressure to higher pressure, and overcomes this difference in pressure by adding energy to the system.
(1) Cavitation is generated at the inlet of impeller, or the region with rapid flow of liquid.
(2) Deterioration from corrosion will be found at the outlet of impeller, or the outlet of pressurized water reservoir.
There is a relative low pressure zone at the inlet of pump, but a high pressure zone at the outlet.
When the pressure at the inlet of pump is lower than the saturated vapor pressure of liquid, the liquid will be vaporized and bubbles are generated.
The bubbles flow to the high pressure zone and ruptured, the vacancies are occupied with liquid in force and generating water hammer to deteriorate the pump parts.
This phenomenon is “cavitation”.
(1) When the bubbles ruptured, liquid particles collided with each other.
Noise and vibration are generated in the pump, and accelerate the violent vibration of pump.
It is cavitation resonance.
(2) Wet-end parts of pump are deteriorated from erosion and corrosion (except positive replacement pump).
(3) There is a sudden drop of pump performance.
The Net Positive Suction Head (NPSH) is the tolerance of energy to avoid liquid vaporization at the inlet of pump (unit in meter).
(1) NPSHa is the Available Net Positive Suction Head.
(2) It is defined in accordance with the suction piping system of pump under the normal condition of flow and temperature (unit in meter).
(3) The value of NPSHa is irrelevant to the construction of pump.
(1) NPSHr is the Required Net Positive Suction Head.
(2) It is measured at the suction of pump by pump manufacturer in accordance with the condition of normal flow of clean water at ambient temperature (unit in meter).
(3) The value of NPSHr can be found from the performance drawing of pump.
No, pumps with flow capacity ≦ 10L/min are free for transaction without E/L, including MD-15F as well as all the EH solenoid metering pumps.
In addition, no E/L is needed for transaction of magnetic capsule.
According to the IEC standard, different insulation materials for motor winding are set for the maximum temperature rise of motor providing that the motor is operated in normal condition at an ambient temperature of 40℃. The insulation classes are as follows.
Class Y 90℃
A 105℃
E 120℃
B 130℃
F 155℃
H 180℃
(1) 220/1/50 (380/3/50)
Asia － Mainland China, Hong Kong, Macau
Europe － Austria, Belgium, Bulgaria, Czechoslovakia, Denmark, Finland, France, Germany, Greece, Hungary, Italy(*1), Luxembourg(*2), Netherlands, Poland, Portugal, Romania, Spain(*3), Sweden, Switzerland
*1 : 125/1/50 (220/3/50) are also available
*2 : 120/1/50 (208/3/50) are also available
*3 : 127/1/50 (220/3/50) are also available
(2) 230/1/50 (400/3/50)
Asia － Singapore
Europe － Norway
(3) 240/1/50 (415/3/50)
Asia － Malaysia
Europe － UK
(4) 100/1/60 (200/3/60)
Asia － Japan(*4), Korea
*4 : 200/1/50 is also available
(5) 110/1/60 (220/3/60)
Asia － Taiwan(*5)
*5 : 220/1/60 (380/3/60) are also available
(6) 115/1/60 (240/3/60)
America － USA(*6), Canada
*6 : 240/1/60 is also available
