General

This applies specifically to pipework for water systems, specifically heating systems, chilled water systems and hot and cold water domestic systems, including mains water.

Flushing, cleaning and water treatment should be carried out on all projects and pipework modification works, unless specifically indicated as not necessary in the particular specification.

All works comply with Statutory Authority and HSE requirements and regulations.
The whole of our flushing, cleaning and water treatment procedures comply fully with BSRIA Application Guides 8/91, Pre-commissioning Cleaning of Water Systems, and 2/93, Water Treatment for Building Services Systems.

Liason is necessary to ensure that any special requirements, such as flushing points, by-passes, dosing pots, pockets, valves, strainers, etc, are provided to enable work to be undertaken fully and completely. Also, information regarding all materials used within the system and hence all the materials that will come into contact with all cleaning and treatment chemicals.

Mains Water Analysis

An analysys of the water is supplied which can be checked with the local water supply authority to ensure that the end analysis results are typical for the site area.

Method Statement

A method statement is provided including details of works sequence, programme, chemicals and concentrations, and any temporary or portable equipment required to complete the works satisfactorily.

The Mechanical Contractor may then notify manufacturers and suppliers of equipment of the proposed system cleaning and chemical treatment processes to establish if any manufacturer or supplier of equipment requires any particular cleaning and chemical treatment process due to size of waterways or materials used, or if any of the methods or chemicals proposed by the Water Treatment Specialist present potential problems or hazards to the equipment supplied.

Preliminary Checks

Prior to carrying out cleaning or chemical treatment process, we ensure that all foreign matter is removed, and that certified pressure tests have been carried out in the parts of the system to be cleaned. We carry out further pressure tests on the isolated sections of the system independently.

To comply with instruction we ensure that circulation has been demonstrated and approval gained on all the parts of the system, leave fully open all valves other than those used to isolate sections. We carry out balancing and certification after the flushing, cleaning and passivation operations. We may also ensure that no damage can occur to any item of plant or equipment due to cleaning and chemical processes, that chemicals used are compatible with system materials, and that all items of plant and equipment subject to damage or blockage due to cleaning and chemical treatment processes are isolated or removed.

All strainers are cleaned out once during flushing and again after the flushing operation is complete.

We comply with all requirements of COSHH regulations during the chemical cleaning and chemical treatment of the system, and where required by the local Water Authority, can provide effluent tanks for storage of all waste products of cleaning and chemical treatment processes. Following local Water Authority approval we either neutralise and dispose to drain of all waste produces, or ensure authorised disposal at registered sites.

Flushing

HES carries out pre-commisioning and flushing to BS7593 for LPHW and chilled water systems.
The whole of our flushing, cleaning and water treatment procedures comply fully with BSRIA Application Guides 8/91, Pre-commissioning Cleaning of Water Systems, and 2/93, Water Treatment for Building Services Systems.

All systems are flushed in accordance with documents specified.

Flushing is undertaken, using portable equipment if necessary, to achieve a full dynamic flush.

Cleaning and Water Treatment, Heating and Chilled Water Systems

Water treatment consists of two separate stages, the exact requirements being as recommended by specialist water treatment equipment and chemical manufacturers, on the basis of our water analysis.

The first stage treatment follows the flushing indicated above, the system then being chemically cleaned using a sequestrant anti-foulant, or alkaline based solutions, acceptable to the NRA and local water authority, having a PH value between 5 and 10.

The second stage consists of a combined corrosion inhibitor and anti-biological fouling agent being introduced.

Cleaning and Sterilisation, Domestic Systems

After completion of the flushing process, the systems are sterilised in accordance with BS 6700 and Health and Safety Executive guidance notes HS(G) 70, ensuring prior to sterilisation that systems have been flushed, cleaned and drained.

Temporary connections necessary to permit introduction of sterilisation chemicals and fluids should be provided, including a 22mm valved drain connection on the incoming main immediately downstream of the mains isolating valve. Once chemicals have been introduced , the systems are left standing for 24 hours and then repeatedly flushed with clean water until all traces of chlorine have been removed. Prior to handover, samples are taken to provide a certificate of conformity.

After chlorination of mains and cold water systems, samples are taken to be analysed and cultured. Duplicate copies of certificates of acceptance as drinking water are provided.

Sterilisation of systems includes all equipment containing stored water.

Documentation

On completion of all cleaning and treatment operations, certificates and documents are issued detailing the exact works undertaken, together with details of all chemicals used, conditions in which the systems have been left, and recommendations for future system treatment. Further copies of these documents should then be incorporated into the O&M manuals.