Contaminated system not only reduce the thermal capacity of hydronic systems, but also increase the wear and tear on pumps and field components. BSRIA AG1/ therefore contains all of the recommendations provided in suitably qualified person with a proven track record in system flushing. A BSRIA Guide Pre-commission Cleaning of Pipework . include internal pipe diameters and revised flushing flow rates Figures 10, 11, 12, .

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The guidelines in Table 4 are based on the practical experience of what can readily be achieved for the majority of new heating and chilled water systems. It is suggested that the designer consult a suitably qualified and experienced cleaning specialist at an sbria stage in the project to review and comment on the proposed design so that the assembled system is amenable to successful pre-commission cleaning using the methodologies explained in this guide. A These criteria are intended for use in pre-commissioning cleaning activity of new heating and chilled water systems, not existing systems.

BG 29 Pre commission cleaning of pipework systems | Stefano Consonni –

The bypass flushingg should be located as close as possible to the heat exchanger and associated control valve, and must be upstream of the means of isolating the coil and Licensed copy from CIS: Take samples in the numbers and locations suggested in Appendix A, Table 10 and analyse for TVC, pseudomonads and sulphate reducing bacteria.

If as part of the flushing and cleaning you are extending or upgrading an existing pipework system, then you bbsria always take water samples from the existing system and these should be tested.

She has been working in the water treatment field of pre-commission cleaning since and has been involved in various steering groups and committees for BSRIA and British Standards. The gap will eventually be filled with a short section of pipe commonly referred to as a fkushing piece. BSRIA wishes to thank the following members of the bsroa group bsra their contributions: Any issues with power supply can delay the flushing process, so look at portable and back-up generators and other solutions in case of power failure.

Turn off the flushing pump and simultaneously close drain valve 1. It is recommended that all temporary mains are cleaned and chlorinated in accordance with [4] BS before being used for system filling or flushing. Alternatively it may be possible to use a temporary water treatment system to re-circulate filtered water and neutralise chemical constituents prior to discharge.


The higher the temperature of the water, or the lower the pressure, the less dissolved gas it can support.

Ask the witnessing authority to witness the flow rate achieved, and record the value. Sometimes used as an aid for cleaning and flushing.

Pipe cleanliness is particularly important in flushjng of increasing incidences of bacterial contamination linked to dirt and other nutrients in pipework.

For the number of samples required in relation to the size of the system refer to Appendix A. This includes sampling methodology, the selection of locations and frequency of sampling, transport and analysis bsra samples and interpretation of results according to the guidelines included in this guide.

Water System Cleaning

The secondary system water should normally be flushed back into the primary pipework header, and from there direct to drain.

When undertaking batchwork flushing of a reverse return circuit consideration must be given to the pipework size changes that take place fushing the centre of the pipe run. Good handling and storage of pipework, and good practice during installation should be encouraged to limit the ingress of debris and dirt. Before final connections are made, a last inspection should be carried out to ensure that items such as tools and welding rods have not been inadvertently left within the system.

Most of the dense debris to be found in a typical system will be below 5 mm in Licensed copy from CIS: Isolate and clean the primary and secondary pump strainers. The Control of Substances Hazardous to Health Regulations as amended COSHH require that the employers, such as the contractor and the chemical cleaning sub-contractor including the self-employedimplement a number of measures in compliance with the Regulations.

Prepare a hsria assessment with supporting health and safety information for approval by the designer, site safety supervisor and CDM coordinator.

Ensure that individual terminal units remain isolated and bypassed. A sufficiently large batch of terminal unit bypasses must be opened to ensure that the required flushing velocity is achieved in the main pipe serving the batch. During this period, the temporary pumps should be used to circulate the clean water and treatment chemicals. It should be remembered that as the batches roll from the furthest terminal unit towards the main floor valve, the flushinh sizes may increase, which in turn may require the batch size to increase to maintain the flushing velocity for the adjacent mains pipework size.

Prior to installation the spool piece should be visually inspected and its condition witnessed by the witnessing authority.


Login if you are bdria member or view our membership benefits. The overall aim is to ensure that, on a daily basis, all water in the system moves a sufficient distance to avoid stagnation. Scale Scale is a build-up of solid material that normally occurs on the internal heat-exchanger surfaces in boilers or condensers.

Where possible, all material and components should be delivered in packaging supplied by the manufacturer or stockist. Measure the flow rate in the pipework onto the floor to ensure that the specified flushing velocity is being achieved. Changes are as follows: The key pieces of information to record are flushing velocity and water sampling results, and this is often where many pre-commissioning companies fall down.

Pre-Commission Cleaning of Pipework Systems

In systems where there is a high volume of water compared to the area of corrodible surface, for example large plastic pipe systems with a few steel radiators, it may be appropriate to install vacuum de-aeration to speed up the reduction in oxygen levels to reduce the risk of corrosion damage.

Figure 8 shows a fan coil branch incorporating two-port pressure independent control valves for the first three fan coils. Residual levels of suspended solids should be low enough not to cause difficulties with commissioning or significant accumulation in low flow areas 5.

The symptoms included blockages at valves and strainers, sludge formation, and severe gassing affecting flow rate measurements and commissioning results. Turn off the secondary pump. During this period water should be circulated and control valves exercised to ensure that treatment chemicals are uniformly dispersed around the system.

Table 3 suggests the minimum size of mains water supply pipe likely to be needed for mains water flushing. Obtain approval from the local sewerage undertaker for the disposal of contaminated flushing water, and in particular, for the disposal of cleaning chemicals.

The type of clean will depend on consideration of the following factors: If approval cannot be obtained make preparations for removal of the waste by other means. Detailed estimates of system volumes down to sub-branch and terminal unit level to allow for initial calculation of chemical dosing during cleaning and subsequent treatment.

These will depend on the grade of stainless steel that is specified.