The impact and requirements of excessive negative pressure in petrochemical equipment on gear oil pumps and seals

[1] The impact of excessive negative pressure on gear oil pumps and seals: In some workplaces, most oil pumps are installed at the bottom of containers, commonly known as backflow. When the gear pump (gear oil pump) stops working, although the valve is closed, there is still a large amount of liquid flowing back into the pump chamber in the pipeline, forming negative pressure. Below are some effects of negative pressure in equipment on gear pumps and seals

(1) The actual output of the gear oil pump is too small, and a large amount of medium circulates inside the pump, causing heat accumulation and gasification of the medium, leading to seal failure

(2) The return flow rate is too high, causing the bottom sediment of the suction tube side containers (tower, kettle, tank, pool) to rise and damage the seal

(3) For long-term shutdowns and restarts without manual turning, the friction pair may tear the sealing surface due to adhesion

(4) An increase in corrosive, polymeric, and cementitious substances in the medium can also cause damage to the seal

(5) Excessive negative pressure in the pipeline results in increased resistance in the outlet pipeline, which can cause low or no flow of the gear oil pump

(6) Excessive negative pressure causes pump vibration, noise, and in severe cases, cavitation, which seriously affects the service life of the pump

[2] Requirements for stainless steel gear pumps in conveying high viscosity food media

Stainless steel gear pumps often encounter problems such as easy sealing leakage, gear damage, poor self suction force, and short service life when conveying high viscosity food media.

. Only a reasonable choice of material for stainless steel gear pumps; Actively improving the processing technology of stainless steel gear pumps and enhancing the machining accuracy of each component of stainless steel pumps, as well as the assembly accuracy of stainless steel gear pumps, can effectively meet the actual needs of our customers

The main issues of stainless steel gear pumps when conveying high viscosity food media include: The gears of stainless steel gear pumps cannot be nitrided, which will mainly cause the conveyed food media to turn black

The shaft sleeve of stainless steel gear pump cannot use steel back composite sleeve as usual. It is recommended to choose materials such as silicon carbide or zirconium ceramic as much as possible

The sealing material of stainless steel gear pumps cannot choose graphite filling media. Skeleton oil seals or double end face balanced alloy mechanical seals should be chosen as much as possible

Stainless steel gear pumps should be equipped with gear reduction motors, variable frequency motors, and stepless speed control motors as much as possible when conveying high viscosity food media. Try to reduce the operating speed of stainless steel gear pumps as much as possible