Precautions and troubleshooting methods for using hydraulic coolers

（1） Instructions for use
1. Operating procedures:
(1) Before starting, check all accessories and instruments and check if all connections are tight.
(2) Unscrew the screw plug (provided by the user) located outside the oil outlet of the cooler, and slowly open the oil inlet valve (at this time, the oil discharge valve is closed). When oil overflows, close the oil inlet valve and tighten the screw plug.
(3) Unscrew the exhaust valve in the cooler pipeline, then slowly open the inlet valve (at this time, the drainage valve is closed). When the water is full, close the inlet valve and exhaust valve. At this time, both the water and oil are in a static state. After heat exchange, the temperature difference gradually decreases.
(4) When the water temperature rises by 5-10 ℃, open the discharge valves for cooling water and oil, and gradually open the inlet valves for cooling water and oil, so that both are in a flowing state. Then adjust the flow of cooling water to keep the oil outlet temperature at normal working condition.
(5) When the cooler malfunctions or stops working normally, the operation steps are to first close the oil and cooling water inlet valves, then close the oil and cooling water discharge valves, and then unscrew the plugs on the drainage and oil discharge interfaces to drain the accumulated cooling water and oil in the cooler.

2. Precautions:
(1) When starting the cooler, it is important to avoid quickly opening the inlet valve, as a large amount of cooling water flowing through the cooler can create a "subcooled layer" on the surface of the heat exchange tube with poor thermal conductivity. Even if there is a large amount of water in the future, it will not provide the best cooling effect.
(2) If galvanic corrosion occurs on the water side, anti galvanic zinc rods can be installed at the designated positions (reserved holes) on the inlet and outlet covers.
(3) Cooling water is usually purified fresh water, and when using river water, a water filter must be installed at the inlet.
(4) To improve heat exchange performance and prevent scale formation, the cooling water temperature should be as low as possible and the water flow rate should be higher.
(5) The oil side pressure of the cooler should be greater than the water side pressure.
(6) In cold seasons and when the cooler is not working, it is necessary to drain all the water to avoid freezing and cracking.

（2） Cleaning method
When the cooler operates for a long time, the surface of the pipe wall gradually accumulates scale, the heat exchange performance decreases, and the cooling requirements cannot be guaranteed. At this time, the cleaning must be stopped. The cleaning cycle depends on the water quality. Generally, internal inspection and cleaning should be carried out every 5-10 months. The method is as follows:
1. Water side cleaning:
Use a hose to rinse the front cover, inner wall of the back cover, and inner surface of the heat exchange tube with clean water at high speed. At the same time, use a cleaning detergent for cleaning and brushing. After cleaning, blow dry with compressed air.

2. Oil side cleaning:
(1) Rinse with a solution of trichloroethylene to circulate the cleaning solution within the cooler. The solution pressure should not exceed 0.6MPa, and the flow direction of the solution should be opposite to the oil flow direction of the cooler. The cleaning time depends on the dirt situation. Then, pour clean water into the cooler for cleaning until the flowing water is clean.
(2) Pour the immersion solution into the cooler. After 15-20 minutes, check the color of the solution. If the corrosion is severe, replace it with a new solution, soak it again until it is clean, and then rinse it with clean water. (If carbon tetrachloride cleaning is used, it should be carried out in a well ventilated environment to avoid poisoning)
(3) After cleaning, perform a hydraulic test, which can also be replaced by a 0.7MPa air pressure test, and then install it on the system for use.

（3） Common faults and elimination methods
1. Insufficient cooling water volume
Elimination method: (1) Open the inlet valve wide. (2) Check if the pipelines, valves, filters, and heat exchange tubes are blocked, and if so, eliminate them.
2. Gas accumulation inside or between heat exchange tubes
Elimination method: Unscrew the screw plug to exhaust.

3. Dirt on the inner or outer surface of the heat exchange tube, increasing flow resistance
Elimination method: Eliminate the fouling on the inner and outer surfaces of the heat exchange tube.
4. When draining water from the return cover (front cover), a mixture of water and oil was found
Elimination method: (1) When the heat exchange tube is damaged and causes leakage, plug it with a pipe plug, but the number of pipe plugs should not exceed 10% of the total number. (2) The sealing between the heat exchange tube and the tube plate is poor and should be repaired by welding or tightened firmly.
5. Leakage occurs outside the flange screw connection
Elimination method: (1) Tighten the fasteners on the flange and replace the sealing gasket. (2) Once the cooler is disassembled, use new sealing gaskets as much as possible.
6. Fixed and floating tube plates, as well as heat exchange tubes, are corroded, causing the cooler to lose its sealing performance
Elimination method: Replace the tube bundle.