Dry duct cleaning equipment

Over time, the duct systems transporting air as well as contaminants in HVAC systems get dirty (whether they are for comfort or technological extraction). First of all because of the dust content of the fresh air drawn in from outside and secondly because the transported contaminants may be deposited on the inside of the duct walls. In order to increase the longevity of the equipment and to maintain air quality, the system has to be cleaned occasionally. This is the purpose of the equipment that is presented below.

The equipment consists of four important parts,
of which two are used for assessment and two for cleaning.

1.) An inspection robot is used to assess the level of contamination in the duct. The robot records a video on a micro SD card as it passes through the duct. It can also be used to provide real-time information by hooking up to a monitor. The robot has a 20 m long cable that sends a signal to a hand-held controller, the computer and the monitor. The length of the duct to be assessed is restricted by this cable length, which means that access doors must be fitted every 20 m. The robot can fit into passageways over 20 cm in diameter; an endoscopic camera is used to examine ducts with smaller diameters. Cameras and LEDs are installed on the front and back of the robot which can be operated with the aid of special controls. The robot is also equipped with a sterilising unit that can apply the necessary disinfectant.

2.) A duct cleaning robot is used to clean the duct system. This is suitable for both round and rectangular ducts. Any narrow sections or bends must be larger than 40 cm and must be horizontal to allow the robot to pass through; otherwise, a DC4 duct cleaning machine as presented below is required. The duct cleaning robot is also equipped with video recording cameras, lighting and a disinfection adapter.

3.) The DC4 duct cleaning machine is used to clean ducts of various sizes. It consists of three main parts: a motor protected by an aluminium housing (the rpm and direction of which can be changed by the control panel; it is also equipped with an impulse generator to avoid getting stuck), a 30 m cable (which includes the adapter for moving the brush, the lead for the video signal, and the system of tubes used for disinfection), and a replaceable round brush. The brush is suitable for removing a variety of different materials and is available in three different materials (nylon, polypropylene and carbon fibre), depending on its intended use.

4.) An endoscopic camera is used for surveying and providing evidence of success. These cameras are generally used for examining systems with diameters under 20 cm, but they can also be used in all other duct types.

This tool is not suitable for removing oily or greasy contamination. The cleaning process can be performed without any threat to the environment. The duct system has to be broken down into 20 m sections. The rotating brush pushes the impurities in front of it, and these are forwarded to the collector unit by the fan by way of a saddle tap. The collector unit can be a filter bag or a container fitted with a filter. The collected impurities qualify as hazardous substances and must be disposed of by incineration. The cleaning process must be repeated until the expected level of cleanliness is reached. This may be followed by sterilisation, but this is generally used only for comfort systems and it may be omitted for technological extraction.

The order of work processes:

♦ Assessment

In the assessment, the size of the duct system must be determined. The dimensions may be determined with the aid of building engineering designs, but it is recommended that the entire system be assessed, including diameters, duct lengths and the location of bends. The assessment also includes an internal survey of the ducting by using the endoscopic camera and the inspection robot. In the case of comfort systems, these measurements should be supplemented by tests performed by an accredited or independent organisation in order to to determine germ count and type. This must be repeated following the cleaning, as together with the video recordings it can be used to confirm success. After the system has been assessed a cleaning plan can be drawn up. The plan includes the location of any maintenance points (saddle taps, cut-out points, service doors, points of disassembly) required by the process. The assessment also sheds light on any machines or tools required for doing the job, including but not limited to: ladders, scaffolding, lifting machinery, compressors, industrial vacuum cleaners, etc. If you place your order for cleaning with us, the cost of assessment will be included in the cleaning costs. Otherwise you will be charged for it.

♦ Preparing an offer

When preparing the offer, the procedures outlined in the section dealing with the assessment are used to determine the time frame, the number of sections, the number of access doors to be installed and the procedure to be used (by robot or DC4, depending on the duct diameter). The brushes wear out during the process, so depreciation is also included as a cost item. The offer price is higher if scaffolding or any lifting machinery is required, and fuel, accommodation and disposal costs are also included. Comfort systems also require disinfectants and protective equipment.

♦ Work

The work process includes the installation of service points at locations defined in the cleaning plan. Closed protective clothing, helmets, dust masks and safety goggles must be worn during work. The duct system must be sectioned off using inflatable balloons to ensure that there is no contamination during cleaning. Extraction points must be created at 20 m distances from the service points. Some of the duct elements must be replaced with saddle taps to provide connection points for fan extraction. Saddle taps must be installed every 20 m, taking the size of the network into account, regardless of whether a robot or DC4 duct cleaning machine is used for cleaning.

♦ Handover – acceptance

The air quality tests must be repeated during the handover-acceptance procedure to confirm the efficacy of the cleaning process. The videos recorded by the endoscopic camera and the inspection robot are also used to confirm the results, providing credible proof of success.