HVAC process:
maintenance of canned motor pump of machine room refrigeration technology (I)
The solution pump and refrigerant pump in the lithium bromide absorption unit are both canned pumps, which belong to centrifugal pumps, but the pump is connected with the motor and is sealed. The rotor in the pump is installed in a very thin stainless steel shell to prevent corrosion. A part of the solution (lithium bromide solution or refrigerant water) at the pump outlet circulates through the pump internally or externally to cool the motor and lubricate the bearings. The inlet is equipped with an inducer to reduce the suction head of the pump.
During the operation of lithium bromide absorption unit, if the canned motor pump is found to be abnormal or fails, the canned motor pump shall be checked and repaired if necessary. In order to prevent problems before they occur and ensure that the unit can operate safely and reliably for a long time, the canned motor pump should be scheduled for maintenance in advance before failure or abnormal conditions occur. Graphite bearing is the most likely to fail in canned motor pump, and its service life is generally 15,000h.
The maintenance of canned motor pump is a highly professional and difficult maintenance work. Due to different models and manufacturers, the structure and size of canned motor pump are also different. Therefore, canned motor pump manufacturers generally undertake the maintenance.
1. Main maintenance items of canned motor pump
1) Check whether the wear of the bearing is within the allowable range.
2) Check the shaft sleeve and thrust plate for damage.
3) Check whether the bolts at each part are loose.
4) Check whether the pump casing, impeller and other components are corroded.
5) Check whether the circulating pipeline and filter screen are blocked.
6) Whether the insulation resistance and coil resistance of the motor are within the allowable range.
7) Whether the terminal blocks of the junction box are intact.
2. Disassembly steps of canned motor pump
1) Disconnect the power supply of the unit, especially the canned motor pump, and lock the switch.
2) After the unit shuts down, pump the unit to a high vacuum, so that there is no non condensable gas in the unit. Then use nitrogen to break the vacuum, and the unit is under positive pressure.
3) The lithium bromide solution and refrigerant water in the unit are injected into the reservoir, which is also pumped to high vacuum.
4) Open the junction box of the pump, disconnect the power cord, and mark the terminals of the removed lead wire respectively to prevent wrong connection when reconnecting.
5) Remove the bolts on the flange at the connection between the motor and the pump body, and mark the two flanges in order. Note: Before moving the motor, support the motor with objects.
6) If there is a circulating cooling pipe connected to the pump body, remove the circulating cooling pipe.
7) Pull the motor out of the pump body with the cover removal bolt, and then check the inside of the pump housing, impeller and inducer.
8) Remove the inducer and impeller. Loosen the locking gasket between the impeller and the inducer, give the inducer a slight impact in the counterclockwise direction, unscrew the inducer, and then remove the impeller. Note: Do not force the impeller to bend the shaft.
9) Remove the front and rear bearing housings from the motor and pull out the rotor assembly from the rear of the motor. Be careful not to scratch the stator shielding sleeve when withdrawing the rotor assembly.
Attention shall be paid during disassembly: do not lose bolts, gaskets, keys and other accessories. After the pump is disassembled, clean the parts with clean water to thoroughly remove the residual liquid in the pump to prevent corrosion and rust.
Production Application
The company’s main business scope includes: central air-conditioning maintenance, cleaning and technical services; cooling tower and fan coil cleaning and maintenance services; custom processing of lithium bromide solution; sales of lithium bromide solution special impurity separators; central air-conditioning host and various zero Sales of accessories; installation and sales of central air conditioning systems, etc.
Widely used in major air-conditioning systems and process refrigeration cold and heat sources; in steel, textile, chemical, electronics, pharmaceutical, food and other industrial and mining enterprises, as well as hotels, theaters, hospitals, and large commercial buildings , Central heating stations and other occasions are widely used.
Contact Us
Ms. Guo- Sales Support & Operations Manager.
Email: mdguolijuan@zjflier.com
Mob: +8615358588768
WeChat: + 86 15358588768
WhatsApp: +86 15358588768
