Positive pressure type explosion-proof motor 7 special test
●Shell strength test
Check the structural strength and tightness of the motor and its associated pipelines with air or inert gas. The strength of the casing shall be 1.5 to 2 times the maximum overpressure specified in normal operation, but the minimum is 200 Pa and the test time is 1 min. The shell, pipe and seal are not damaged.
●Fire flower spray test
The air inlet and outlet of the motor ventilation duct shall be located in a safe place free of explosion hazard. If the exhaust port is located in an explosion-hazardous location, the exhaust port shall be fitted with a device for fireproofing, arcing and flammable material to be blown out of the casing. If there is a risk of sparking at the joint between the shaft and the joints of the pipe, a spark can be artificially created, such as igniting certain combustible materials, and then ventilating normally to see if the spark can be blown out of the gap.
●Minimum wind pressure test
Connect the fan and air duct according to the design requirements, and connect the valve to adjust the air pressure and air volume at the air inlet. The measurement point of the wind pressure is determined according to the structure of the motor, the flow path of the air flow, and the change in the size of the air path. The pressure measuring point should be set at a place where the wind pressure is low and the explosive gas may enter the gap of the outer casing, and is generally set at the following positions: (1) inlet and outlet ports. (2) The place where the pressure measuring instrument is to be installed. (3) Where the outer casing may leak and gaps, such as the shaft extension. (4) Where the airflow changes abruptly.
U-tube pressure gauges, micro-pressure gauges and Pitot tube are generally used for measuring wind pressure. Adjust the flow rate and pressure value of the air inlet. When the requirements of the technical conditions are met, measure whether the positive pressure value of each pressure measuring point exceeds 50Pa. The test shall be carried out separately at the standstill and rated speed of the motor.
● Ventilation dead angle inspection test
The motor casing is filled with hydrogen (nitrogen or carbon dioxide gas) at a concentration of 60% ± 1%. Ventilation and purging shall be carried out with a wind volume of 5 times the total volume of the motor casing and the auxiliary pipe or according to the air volume and time specified in the product manual. Then, the gas analyzer is used to measure at 3-5 points of the expected dead angle of the ventilation. The above gas concentration ≤ 1% is acceptable.
