| 摘要 |
An extraction cleaning device is of the type having a cleaning head (60), a vacuum system (70, 80, 90) for applying suction at the cleaning head, a holding tank (10) for holding cleaning liquid, a pump (20) for pressurizing the liquid, and a delivery line for delivering the pressurized liquid to the cleaning head wand, where it is sprayed onto a carpet, upholstery, etc. The device is improved by the addition of a pressure reduction valve, having a calibrated orifice, which is hydraulically connected between the liquid delivery line and a return line to the holding tank. When the reduction valve is open, the delivery line pressure is reduced by the added leakage; this allows switching between high pressure jet spray for carpets and low pressure jet spray for upholstery, drapes, etc. For easy opening and closing of the reduction valve, it is preferably a solenoid valve activated by a switch.
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