(a) DW/ Specification for sheet metal ductwork (low-medium- and high pressure) .. Air leakage of the assembled unit shall be to HVCA Standard DW/ Duct Work Construction to DW/ DW/ is recognised throughout the UK as the Standard Specification for ductwork manufacture and installation. “It will be. DW/ Specification for. Sheet Metal Ductwork. Low, medium and high has gained national and international recognition as the industry standard.
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All the seams and joints integral to a fitting shall be sealed to the same standard as the duct. BS Carbon steel plate, sheet and strip. Following this advice will make the provision of the Regulation 38 information much easier. The damage to the zinc coating is negligible in most cases. A competent installer should deliver a fully sealed system providing a low maintenance, long life solution.
They are ductile and formable, but forming loads are higher than for mild steels and suitable, robust equipment is required. Use of volume control dampers and turning vanes are not recommended. All are weldable and have good general corrosion resistance to normal and mildly corrosive atmospheres.
The load-bearing capacity of the construction can be assumed for a specific period of time. The highest standards in the management and control of standadr services systems and facilities.
However, we should emphasise that standadd it does not form any part of the specification and should be used as reference only. Table 23 Extract from BS.
The designated Director has the overall responsibility for ensuring that company knowledge is updated on current legislation, guidelines and codes of practice, and the dissemination of this information to employees and sub-contractors. BS Schedule of paint colours for building purposes.
BS EN Cold rolled uncoated and zinc or zinc-nickel electrolytically coated low carbon and high yield strength steel flat products for cold forming. Where successive failures are identified there shall be a right to require the ductwork contractor to apply remedial attention to the complete ductwork system. Typical arrangements of roof penetrations are standars in Figs. Designers and surveyors should note that bills of quantities should provide a full description of the items required.
Particular care must be taken in the sealing of these joints. Curtain fire dampers generally provide an E classification to BS ENas they do not have the cold leakage characteristics to achieve the ES classification.
DW standard – Pro-Duct Clean
It also gives guidance on the continuing maintenance for smoke control systems, ventilation ductwork and other equipment with fire safety performance or requirements. Used for simple operations and designed up to mm on the longest side. The system designer may, for example, indicate that a particular system is tested as follows: For example, some large systems could well be sttandard for leakage limits as follows: Further more detailed advice on corrosive rates may be obtained from the Institute of Corrosion www.
BS EN Continuously hot-dip coated steel sheet and strip.
Duct work construction to DW/144
Aluminium cladding is a more rigid protective finish than most other proprietary weather-proof jacketing systems, and is less susceptible to bird damage. According to the Regulations, the requirement for CE marking will apply to: The system designer shall specify damper locations and select the damper type as defined in Type 2B Cold rolled, softened, descaled and lightly worked with polished rolls.
If tested unprotected Steel Suspension devices Drop Rods can be used up to 1. System designers and surveyors should note that bills of quantities should provide a full description of standatd items required.
Dampers shall have casing leakage classes to meet BS EN The test results on the duct are applicable to the following under and over pressures depending on the tested pressure. Tata Steel are able to provide further detailed information on the subject of coil storage recommendations and practices on their website.
Please copy and paste this embed script to where you want to embed Embed Script. Procedures for the selection of all employees and sub-contractors need to be set down with requirements for items such as personnel protection equipment, skill cards, method statements, risk-based assessments, insurances and the safety document. Guide to Good Practice: They are aimed at improving the management of health, safety and welfare to reduce the large number of serious and fatal accidents which happen every year in the industry.
Similarly, the operating pressure will vary throughout the system and as leakage is related to pressure the calculations are complex.
Refer to right hand page opposite for additional information relating to Notes 10 to 13 in Table 2. As flexible ducts have a higher resistance factor than conventional ductwork of the same diameter, it is generally recommended that in any application the length does not exceed 6 x diameter but this can be varied if due allowance is made in the system design for the pressure drop.
BS EN — 3 or 4 define how to give a fire resistance classification as a result of testing. The ductwork contractor shall provide documented evidence of the calculations used to arrive at the allowable loss for the section to be tested and the client, or his agent, shall witness and sign the results of the test.
Each range however has advantages and disadvantages with regard to both manufacture and installation costs.