The fundamental operating principle of ultra-high-pressure (UHP) water jetting involves pressurizing water-using a high-pressure pump or intensifier-to high or ultra-high levels, with operating pressures exceeding 70 MPa and potentially reaching 90,000 psi or higher. The pressurized water is discharged at high speed from a tiny nozzle to form a jet, achieving velocities of 300–500 m/s-ranging from subsonic to supersonic speeds. The jet structure comprises an initial segment, a core segment, and a dissipation segment. The initial segment is suitable for material cutting; the core segment is appropriate for cleaning and rust removal; and the dissipation segment is primarily used for cooling and dust suppression. The jet's impact, shear, or erosive action on the material surface enables functions such as cutting, fragmentation, and cleaning. This process involves dynamic fracture, with distinct failure mechanisms for brittle versus ductile materials.
UHP water jetting equipment is a fluid energy release system featuring a nozzle; its core components include high-pressure generation equipment, a control system, an actuation mechanism, and auxiliary systems. High-pressure generation equipment-such as high-pressure pumps, UHP pumps (operating at ≥100 MPa), or intensifiers-produces the high-pressure water. The control system, comprising safety valves, pressure-regulating valves (overflow/unloading valves), control valves, and electrical control cabinets, manages and protects the system. Actuation mechanisms-such as spray guns, spray heads, and nozzle assemblies-form and manipulate the jet. Auxiliary systems encompass components like pressure gauges, high-pressure or UHP piping (rigid and flexible), water tanks, feed mechanisms, and power distribution boxes. Taking UHP cleaning equipment as an example, typical components include a high-pressure clean water pump, electric motor, overflow valve, safety valve, foot-operated valve, spray gun, UHP piping, water tank, and power distribution box.
System components must withstand extreme operating pressures, spanning the 10–500 MPa range. During pressure testing, the test pressure must exceed the operating pressure; for instance, if the operating pressure is approximately 200 MPa, the test pressure must reach 300–400 MPa. From a safety perspective, components located near the operator-such as the spray gun, ultra-high-pressure hoses, and their fittings-are subject to strict service life limits (generally not exceeding 500 hours) and require proper maintenance. The design of the spray gun's recoil force must comply with safety standards; specifically, the recoil force of a handheld spray gun must not exceed 200 N.
