1. Field of the Invention
This invention relates to a nozzle or head of the type mounted on the ends of flexible hoses and used for the cleaning of pipes, ducts and waste water conduits using high velocity streams of liquid, and more particularly to such a nozzle which produces a pulsating flow.
2. Description of the Prior Art
Waste conduits containing caked or loosely adherent sludge, sediment, stone and other solid articles have been cleaned with the aid of a self-propelled nozzle or head affixed to the end of a flexible hose and having a plurality of rearwardly directed jets of high velocity fluid, usually water. In these systems, the reaction force upon the nozzle propels it through the conduit while entraining the attached length of flexible hose therealong. The fluid jets concurrently loosen adherent materials and carry them back through the conduit. When the nozzle is retracted in the direction of the advance of the nozzle by drawing upon the hose or a cable affixed to the nozzle, the rearwardly directed streams of fluid act to scoop sediment and contaminants away from the walls of the waste conduit and thereby provide an additional loosening and cleansing effect. Examples of prior art self-propelled nozzles are shown in U.S. Pat. Nos. 1,176,518 issued to Burns, 1,628,070 issued to Sladden, 3,080,265 issued to Maasberg, and 3,321,184, issued to Goss.
The flow rate of fluid emitted by the nozzle and the pressure of the fluid are limited by the output of the pump supplying fluid to the nozzle and the capacity of the flexible hose which connects the pump to the nozzle. The pressure and flow rate of the fluid are regulated in the nozzle by the size and number of the jets or orifices in the nozzle through which the fluid flows. With the pump producing a maximum flow rate at maximum pressure of the pump outlet, the pressure and flow rate of fluid through the nozzle are limited by the capacities of the pump and the connecting hose.
While the cleaning effect produced by these prior art nozzles has been sufficient where the degree of sedimentation is not excessive and where the walls of the conduit are coated with a loosely adherent layer of sludge, these nozzles have encountered difficulty in removing heavy accumulations of adherent sludge or caked-on material even when the water dispensed by the nozzle is at high velocity with the maximum pressure and volume possible.
It has been proposed to produce a pulsating jet of fluid from the nozzle in order to increase the effectiveness of the nozzle in removing caked sludge from the walls of the conduit. Such a pulsating jet has been produced by using a pump which produces a pulsating flow of fluid through the flexible hose to the nozzle. This pulsating system requires a specially adapted pump which can be quite expensive. In addition, the effectiveness of this pulsating system has been limited by the capacity of the pump and the capacity of the flexible hose to carry a given maximum rate of fluid through the hose from the pump to the nozzle. Thus, when the pulsating flow from the pump reaches its maximum flow rate, this maximum flow rate cannot be any greater than the maximum flow rate produced by a continuous flow because it reaches the maximum capacity of the hose. The effectiveness of this pulsating spray is, therefore, not much greater than a continuous spray. Another problem with this pulsating system is that the pump is often a considerable distance away from the nozzle and this pulsating flow produced by the pump loses some of its effectiveness as the fluid travels through the flexible hose to the nozzle.