Hydroblasting Equipment and Components
Domain focus
Hydroblasting Equipment and Components tests how pumps, hoses, lances, nozzles, and pressure controls work as a system, and how changing one component alters pressure, flow, and safety everywhere else.
Core rules
- Positive-displacement triplex plunger pumps are standard; ultra-high-pressure work may use intensifiers. Because displacement is fixed, pressure is set by the nozzle orifice and the relief valve, not by throttle position alone.
- The pressure chain is only as strong as its weakest link: set the relief valve no higher than the lowest-rated component in the circuit.
- Hoses must be rated above maximum pump pressure, inspected before use, and fitted with whip checks or safety cables at every joint.
- Nozzle flow follows GPM ≈ 29.9 × D² × √P (D in inches, P in psi). A larger orifice demands more flow and drops pressure; a smaller orifice raises pressure until the relief opens.
- Lances are rigid for surface work and flexible for tubes; the deadman control must stop flow when released.
Worked example
A pump is rated 20 gpm at 10,000 psi and carries a 0.08 in nozzle. Q = 29.9 × 0.0064 × 100 ≈ 19 gpm, so the unit is near its rated point. Fit a 0.10 in nozzle and demand at 10,000 psi is about 30 gpm; the pump cannot supply it, so pressure falls to roughly 4,500 psi. The operator who "turns up the pressure" is really just opening the relief valve.
Traps
Blaming the pump for low pressure when the nozzle is worn oversize; fitting a smaller nozzle without checking the relief setting; skipping whip checks; and kinking a hose to stop flow.