Handheld high-pressure spray guns are often used for plane cleaning, such as paint removal and rust removal. Flexible and rigid spray guns are commonly used for pipe bundle cleaning, such as heat exchanger cleaning. Although they are all called cleaning spray guns, they are used in different ways. The following are some safety recommendations for using spray guns, which can be used as a reference for cleaning operations.

（1） Handheld spray gun operation

1. Control: The spray gun shall be equipped with a control valve, which can be directly controlled by the spray gun operator.

2. Operation; The spray gun pressure shall rise slowly; The spray gun must be locked after it is closed.

3. Multiple gun operation: when multiple guns are used at the same site, the operators must set up guardrails or maintain sufficient space distance to prevent each other from being injured by high-pressure water.

4. Minimum length of spray gun: the minimum length of spray gun shall ensure that the nozzle touches the ground without touching or above the vamp when the operator is holding the gun downward.

（2） Flexible spray gun operation

1. Control: The flexible spray gun shall be connected with a foot control valve, and the spray gun operator can directly control the valve switch.

2. Prevent the nozzle from retreating: if an automatic cleaning device is used, it can be controlled remotely. If manual cleaning is used, effective coercive measures should be taken to prevent the nozzle from retreating in the reverse direction along the nozzle feed direction from the pipe to be cleaned.

3. Slag discharge clearance: there should be enough clearance between the outer wall of flexible spray gun, rigid spray gun, nozzle and the inner wall of the pipe to be cleaned, so that waste water and slag can be discharged smoothly, otherwise it is easy to block.

4. Pressure rise: during operation, the nozzle shall extend into the pipe fittings to be cleaned for a sufficient length before pressure rise to prevent the operator from being injured by the reflection of the spray gun; On the contrary, the system must be depressurized before the nozzle exits from the pipe fitting.

5. End mark: a clear mark shall be made on the outer wall of the high-pressure pipe no less than 50cm from the nozzle, that is, within the length range where the jet may hurt the operator.

6. Nozzle connection: when the length of the nozzle and its rigid joint is less than the diameter of the pipe to be cleaned, a section of hard pipe with a length not less than the diameter of the pipe to be cleaned shall be connected after the nozzle, or another protective barrier shall be set to prevent the nozzle from reversing 180 °, so that the jet will shoot at the operator.

（3） Rigid spray gun operation

1. Control: The foot control valve shall be connected to the rigid spray gun, and the spray gun operator shall directly control the valve switch.

2. Length of spray bar: The length of rigid spray gun and its extended spray bar shall not exceed the range that can be controlled by the operator. If it must be exceeded, an auxiliary operator shall be equipped to control the spray bar.

3. Protective cover: when the rigid spray bar is used for operation, the protective cover shall be installed on the spray bar. To prevent the operator from being injured when the nozzle accidentally exits.