ProMax Quick FullJet

The new nozzles give ever consistent wetting across the full-cone spray pattern. Spray tips can be changed in seconds without tools, to vary the spray width and flow rate.

Cleaning and restoration of the external fabric of the Norman Shaw South Building on the Thames embankment is going forward rapidly with the help of new spray technology developed for industrial use. The process is showing excellent results, despite the extra problem of removing camouflage. The 90-years-old building, originally part of London’s police headquarters as an extension of the first New Scotland Yard, is thought to be the last non-military structure still clad in its wartime protection against enemy bombers.

The first specialist to identify the unusual carbon-black soiling, which he had uncovered under years of traffic deposits and metropolitan grime, was David Frost, founder and MD of contractors Cleaning & Restoration of Historic Buildings (London). Camouflage had not been envisaged in the standard cleaning specification, which called for pre-scaling water application followed by abrasive treatment.

At Norman Shaw South, his company has been entrusted with the cleaning and restoration of all external structural features from roof to ground level – a combination of brickwork, granite and Portland stone totalling some 7,000m2. Taking up the work after one façade had already been treated, he was able to convince sceptics that the approved technique could not properly clean masonry here without the risk of damaging it.

The key to his alternative solution was to apply the water more effectively by using ProMax QuickJet nozzles – a new range of industrial spray nozzles recently developed by spraying systems. David Frost believed that the ‘ProMax system’ will change techniques throughout the cleaning/restoration industry because of the superiority of these ‘F1’ nozzles traditionally used for applying water to brickwork and other masonry.

Many advantages of the new nozzles have been demonstrated practically on the current project.

One is better concentration of the spray and more even coverage of droplets across the full-cone spray patter, as compared with the hollow-cone pattern of the F1. The results are more efficient wetting, better use of water and faster progress of the state of the job.

The nozzle is a two-part precision moulding in ProMax glass-reinforced plastic, which is strong and chemically resistant. Once attached to the hose, the body stays I place and accepts a wide range of interchangeable colour coded spray tips. The tip can be changed or replaced in seconds, without tools, so that the flow rate and spray angle can be chosen at will to fine-tune the wetting process and suit the structural features of the building, the surface type and condition and the nature of the soiling. An optional ball-type mounting, which allows the direction of the jet to be adjusted without moving the nozzle, is also proving useful for targeting awkward corners ad angles.

The flexibility of the whole system helps to minimise the volume of water needed to prepare the surface for further treatment. The Only way to change the flow rate of the F1 is to alter water pressure and the direction of the spray is not adjustable.

Another advantage of the new system is consistency. The traditional nozzle can be adjusted to change spray angle, but in practice it has a tendency to adjust itself while spraying, which calls for continual checking and correction. The spray pattern of each QucikJet tip is fixed and constant.

Overall, QuickJet nozzles have been shown to minimise water consumption, avoid disposal problems, improve site housekeeping and save time in various ways, while giving a more effective, more efficient performance. In turn, it means a softer abrasive can be used at the next stage, so avoiding risk of damage to the masonry.

Having seen how the system performs on the Norman Shaw South building (a stiff first test) David has begun to apply it on other contracts. DJF have been using the nozzles since December 2001.

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