GB2109271A

GB2109271A - Pulsating liquid jet apparatus

Info

Publication number: GB2109271A
Application number: GB08233623A
Authority: GB
Inventors: Donald Whitehead
Original assignee: VAULDALE ENGINEERING Ltd
Current assignee: VAULDALE ENGINEERING Ltd
Priority date: 1981-11-25
Filing date: 1982-11-25
Publication date: 1983-06-02
Also published as: GB2109271B

Abstract

The apparatus is suitable for cleaning a pipe by a nozzle (18) which is forced through the pipe by liquid pressure. High pressure pump 10 has its outlet 12 and inlet 22 interconnected by bypass line 20 in which is disposed a pilot valve 26 normally held closed by a spring 36 whose action is opposed by liquid pressure from a hydropneumatic accumulator 30 whose liquid side is also connected by way of a variable restriction 28 to high pressure output line 14 leading to a flexible high pressure hose 16 having a jet nozzle 18. This arrangement ensures that liquid emerges at the nozzle(s) 18 as high pressure jets, directed both in the forward and reverse directions so that when the nozzle is introduced into the pipe (e.g. a drainage pipe) the jets will progress the nozzle(s) 18 and the following flexible hose 16, through the pipe. <IMAGE>

Description

SPECIFICATION Pulsating liquid jet apparatus This invention concerns pulsating liquid jet apparatus.

The use of high pressure water for the cleaning of blocked and silted drainage or other pipes is a well known and widely used technique. The method generally employed is to supply water, at high pressure, through a length of flexible high pressure hose attached to the downstream end of which is a nozzle with a number of jets through which the water exits at high velocity. This nozzle is introduced into the drainage or other pipe to be cleared and the arrangement of the jets is such that water ejected rearwards acts both to propel the nozzle and hose forwards and also to scour the walls of the pipe. If the pipe is known to be seriously blocked, a forward facing jet may also be a feature of the nozzle in order to blast a way through the obstruction.Using this technique with a variety of nozzles, hoses, and water flow and pressure variables, it is possible to penetrate blocked and heavily silted drains, up to about 100 metres (about 300 feet) in length, purely by the self-propelling action of the nozzle attached to the end of the high pressure hose. Such a penetration length is generally adequate for most industrial, municipal and highway applications due to the provision of regular manhole access.

A relatively new application of the technique is in the cleaning and maintenance of land drainage systems where it is not uncommon to find drainage pipes extending to lengths of up to about 600 metres (about 2000 feet). In order to achieve this length of penetration, which is desirable in order 20 to avoid having to dig up the drainage line to gain access at intermediate points, some other technique must be employed. It is a known principle that if the flow of the nozzle is interrupted on a regular cyclic basis causing a pulsating action the nozzle and hose will continue to progress into the pipe beyond the point which can be achieved by the steady pull obtained from rear facing jets alone.

Interruption of the flow to the nozzle may be brought about in a number of ways at least one of which is currently available commercially. This involves the selective by-passing of flow from one cylinder of a three-cylinder piston pump.

An object of the present invention is to provide a form of apparatus operative to generate a pulsating jet of liquid, such as water, suitable for use in the cleaning of pipes as above discussed, which apparatus is of relatively simple construction involving primarily components which are readily available commercially.

With this object in view, the present invention provides pulsating liquid jet apparatus comprising a high pressure pump the inlet and outlet of which are connected by a by-pass wherein is a valve by which flow through the by-pass can be controlled, the outlet being connected by way of a flexible hose to one or more jet nozzles, and a pressure accumulator being connected by way of a restriction with the outlet and serving to supply control pressure to the valve cyclically to open and close the latter thereby to provide for the production of a pulsating liquid jet at the nozzle(s).

The invention further provides, of course, a method of cleaning a drainage or like pipe using pulsating liquid jet apparatus as aforesaid which comprises introducing, into the pipe, the hose and nozzle(s) of the apparatus, and operating the pump, thereby to generate a pulsating liquid jet at the nozzle(s) so as to clean the pipe and cause the hose and nozzle(s) to progress therethrough.

The invention will be described further, by way of example, with reference to the accompanying drawing, in which the single figure is a schematic diagram illustrating a preferred embodiment of the pulsating liquid jet apparatus of the invention.

In the apparatus illustrated in the drawing, a high pressure pump 10, preferably but not exclusively a piston-type pump, is used to force water, by way of its outlet 12, into a high-pressure delivery line 14 which connects to a flexible high pressure hose, indicated very diagrammatically by a zig-zag line at 16, at the downstream end of which are one or more nozzles as indicated at 18. Connected to the high pressure delivery line 14 at points relatively close to the pump outlet 12 are a full bore by-pass line 20 which connects back to inlets 22 of the pump 10 and a pilot connection line 24. The by-pass line 20 is normally closed by a two-position spring-biased pilot operated valve 26 which is illustrated as a shuttle-type valve, but may be any suitable form of pressure-actuated valve.

The pilot connection line 24 is connected by way of a variable restrictor 28 to the fluid side of a gas-filled diaphragm-type pressure accumulator 30 sometime known as a hydropneumatic accumulator. The pressure on the accumulator side of the restrictor 28 is applied by line 32 to pilot port 34 of the twoposition valve 26.

The method of operation of the apparatus is as follows. Assuming the pump inlet 22 to be con necked to a water supply and the pump 10 operating, as the flow from the pump 10 rises to a maximum, the pressure in the delivery line 14 rises to the operating level determined by the characteristic of the nozzle(s) 18.

This pressure level operative in the delivery line 4 causes liquid to flow through the restrictor 28 to charge the accumulator 30 and consequently raising the pressure downstream of the restrictor 28 i.e. the pressure applied to the pilot port 34. When the pressure applied to the valve 26 by way of the port 34 reaches the level at which spring 36 of the valve 26 is overcome, the valve 26 changes over from its illustrated closed condition to an open condition in which the by-pass line 20 is opened. The pump output is then free to circulate on no load. Conse quentlythe pressure in the delivery line 14 drops.

The pressure in pilot connection line 24 between the restrictor 28 and the accumulator 30 is now higher than the pressure in the line 24 at the other side of the restrictor 28. This causes the accumulator 30 to discharge back through the restrictor 30 and the pressure apparent at the pilot port 34 to fall. When this pressure has fallen to a level at which the spring 36 can become dominant, the valve 26 changes back to its illustrated closed condition. The cycle then begins again as full pump flow is directed to pass through the nozzle(s) 18 causing the pressure in the delivery line 14to rise again.

The frequency and amplitude of the cyclic pressureflow variations may be controlled by the relative settings of the spring 36 and the variable restrictor 28.

Typical operating values would be: Pump fixed output - about 68 litres (15 gallons) per minute Maximum steady line pressure- about 175 kg. sq.

cm (about 2500 psi) Cyclic pressure range- 35 to 105 kg. sq. cm (about 500 to 1500 psi) Frequency- 50 to 150 cycles per minute Pilot pressure operating level - 70 to 85 kg. sq. cm (approx. 1000 to 1200 psi) It will readily be understood that the steady flow from the pump 10 and nozzle(s) 18 is interrupted by the opening and closing of the by-pass line 20 automatically on a cyclic basis. The resulting pulsating action may be employed to cause the nozzle(s) 18 attached to the downstream end of the high pressure hose 16 to penetrate into a drainage or other pipe (not shown) over distances far in excess of what may be achieved by conventional self propelling action derived from a non-pulsating flow at the nozzle(s) 18.

Naturally, the invention is not confined to the precise details of the illustrated example and variations may be made thereto within the scope of the following claims. Naturally the use of the apparatus is not confined to water, and it can be employed with other liquids required to be ejected in a pulsating manner.

Claims

1. Pulsating liquid jet apparatus comprising a high pressure pump the inlet and outlet of which are connected by a by-pass wherein is a valve by which flow through the by-pass can be controlled, the outlet being connected by way of a flexible hose to one or more jet nozzles, and a pressure accumulator being connected by way of a restriction with the outlet and serving to supply control pressure to the valve cyclically to open and close the latter thereby to provideforthe production of a pulsating liquid jet at the nozzle(s).

2. Apparatus as claimed in claim 1 wherein the valve is a pilot valve spring-loaded into a closed position in which the by-pass is closed for the entire pump output to pass to the nozzle(s).

3. Apparatus as claimed in claim 1 or wherein the pressure accumulator is a hydropneumatic accumulator.

4. Apparatus as claimed in claim 1,2 or 3 in which the restriction is variable.

5. Pulsating liquid jet apparatus substantially as hereinbefore described with reference to an as illustrated in the accompanying drawing.

6. A method of cleaning a drainage or like pipe using pulsating liquid jet apparatus as defined in any of claims 1 to 5, which comprises introducing, into the pipe, the hose and nozzle(s) of the apparatus; and operating the pump, thereby to generate a pulsating liquid jet at the nozzle(s) so as to clean the pipe and cause the hose and nozzle(s) to progress therethrough.

7. A method of cleaning a drainage or like pipe substantially as hereinbefore described with reference to the accompanying drawing.