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Water Usage In Hydrodemolition

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Water Usage Is Less When Using An Aqua Jet Robot

A common mistake for businesses who are new to hydrodemolition is to think that a larger water jetting pump with a higher flow rate uses more water than a smaller hand-held one.

How Much Water Will We Use?

We are always happy to explain how much water we will use before we commence work. For reasons of safety and convenience, we prefer to use our robot and power pack.

Many people naturally assume that a larger pump will use more water, but this is not necessarily true. In theory, the flow rate should directly affect the rate at which the concrete will be taken away from the surface that is being worked on. But in practice, this is often not the case. Here we will explain a little more.

Fig 1. When using a hand-held lance as opposed to a robotic one, jets are often not quite held at exactly the right angle. This means that hand-held lance jets are generally around 30% less effective than the larger robotic jets.

150hp pump (40 litres/[email protected]), with an operator using a hand-held lance, may remove 0.75-1.0m3 of concrete in a single shift. Compare this to:

700hp pump (260 litres/[email protected]), with the same operator using an Aquajet Robot, will remove 6.5-10.0m3 of the same concrete in the same amount of time.

As this instance illustrates, along with the information you can see in Fig.2, Aqua Cutter systems allow the operator a greater degree of control over the jet. This means that the water is being used much more efficiently and productively than it would be during hand lancing, getting rid of greater amounts of concrete in the same time span. So although it may seem that the bigger pumps would use more water, they can actually save up to 25-40% of the overall volume used. This is why these systems are such a great option for businesses looking to engage in more environmentally friendly working practices.

When we explain that we need to use 260 litres of water per minute, this seems like a lot. But we ask you to consider the information presented in this table. Hydrodemolition water usage and typical breakout comparisons (21st November 2013). This information is taken from Break out rate sheets.

Hydrodemolition diagram showing surface area of jet on impact

Fig 1.

As an example, consider the information presented in the yellow highlighted sections. Here we have stated that when a pump using 1000 bar at 57 litres per minute is used, this will give a reaction force of 421 Newtons. If we can remove 0.85m3 of concrete in one work session, this means that the pump will require 32,000 litres of water per m3 of concrete broken out.

If we then consider the green “power pack 2″ line, we can see that the reaction force is 4.5 times greater at 1926 Newtons. Although this pump is using almost five times the amount of water as the pump in the yellow example, the reaction force is also nearly five times greater. Unlike a human operative, the robot can consistently carry out the same action as many times as needed without getting tired or losing accuracy.

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