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Know your nozzle – key facts about tube and drain cleaning nozzles

Home Engineering Pipes & Tubes Know your nozzle – key facts about tube and drain cleaning nozzles

PIPE cleaning machines all have one thing in common: they need special nozzles designed for each specific application. That’s according to Hawk Pumps, which says high pressure pump machines are available or can be custom designed. But the choice of the correct nozzle, water flow, and pressure is very important.

The various types of nozzles have a few things in common. Most have jets facing backwards, which serve two main purposes: to pull the hose into the pipe and to clean the pipe’s walls.

For cleaning walls, the jets tend to face backwards and outwards at a large angle. Sometimes, a forward-facing jet is not necessary, which allows larger, rear facing jets to be fitted.

If the problem is a blockage, a forward-facing jet is important, because the rear facing ones don’t spray outwards as much, making it harder for the forward pulling power to overcome the negative effect of the forward jet.

According to the company boiler tube nozzles usually require relatively low volumes at higher pressures to cut through the scale, which can be extremely hard.

They don’t depend much on rear jets and don’t have front ones, but rather have side jets on a spinning body. Occasionally, when the tube is all but blocked, a chisel nozzle with sharp hardened facets in front is needed to physically break the scale with forward facing jets. These nozzles are fitted to rigid pipes, rather than flexible hoses. The pumps needed here have low volumes (about 20 l/min) at 500 bar pressure.

Slurry transfer pipes require simple “bomb” shaped nozzles with rear facing jets. Here, depending on the pipe diameter, the pumps are of a medium (typically 80 l/min) flow at about 150 to 200 bar. Occasionally, a nozzle with spinning chains will be needed to improve the cleaning effect.

Drain pipes also usually are cleaned using “bomb” nozzles and require pumps similar to the slurry pipe applications. If the pipe is blocked, a nozzle with a front jet is called for. Hard blockages need cutter nozzles.

Sewers vary in diameter and have different degrees of blocking. For normal domestic sewers, a 30 l/min pump at 150 to 200 bar will suffice. The nozzles required are simple mini-bombs with forward and rear facing jets. Mains sewers are of a large diameter (up to 300mm but usually about 200mm) and these require a minimum of 80 l/min at 150 to 200 bar.

A 120 l/min pump helps to pull the hose better, especially where the sewer has a long space between manholes. Cutter nozzles, chain flail nozzles and bomb nozzles are all used in this application.

Rainwater and stormwater drains require much larger pumps. They usually need 150 to 200 l/min at 150 to 200 bar. Bomb nozzles can be used, but where sand is the main problem, the “flounder” nozzle is the most effective. This nozzle consists of a block of metal with a pointed front and usually four rear facing nozzles.

When the nozzles reach sand, they tend to ride up and over it and in doing so, cause the rear jets to agitate and fluidise the sand. The large volume of water carries the sand back to the manhole where it is removed, either physically, or by means of a jet pump which only uses a small portion of the pump flow to push the sand out.

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