4"three phase submersible electric pumps * Conform to international standard of IEC34-ICE, whole blocked asynchronous motor with squirrel cage rotor. * Outer shell, shaft and bottom made of stainless steel. * Copper alloy or chromium plated cast-iron upper adaptor. * Pressure automatic adjusting device made of oil and water proof reinforced butyl-rubber. * Flange connector under the standard of NEMA (USA National Electrical Manufacturing Association). * Lacquer-coated wire conformed to USA standard of NEMA MW37-C. * Assure double safety by using the unique released high pressure device.