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Pressurisation Systems

Pressurisation Systems . Colt Technical Seminar. A brief history of Colt. Private Company founded in 1931. I J O’Hea OBE (1897 - 1984) 2009 Group Turnover £170 million Manufactures in the UK, Holland, Saudi Arabia, China and Singapore. “I J O’Hea. Colt Founder ”.

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Pressurisation Systems

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  1. Pressurisation Systems Colt Technical Seminar

  2. A brief history of Colt • Private Company founded in 1931 • I J O’Hea OBE (1897 - 1984) • 2009 Group Turnover £170 million • Manufactures in the UK, Holland, Saudi Arabia, China and Singapore “I J O’Hea.Colt Founder”

  3. Current UK Business markets • Smoke Control • Solar Shading • Natural Ventilation • Louvre • Environmental Comfort Control

  4. WHY PRESSURISE? Approved Document B to the Building Regulations requires smoke ventilation to escape stairs and, under some circumstances, common lobbies and/or corridors in residential buildings. Pressurisation is one way of meeting this requirement Alternatives to pressurisation are: Natural AOV’s Natural Shafts Mechanical ColtShaft

  5. Alternative to natural ventilation when escape stairs or fire fighting stairs are landlocked A requirement for some fire fighting stairs Provides much better protection than natural ventilation of stairs Note: BRE shaft and Colt Shaft have significantly reduced the market for pressurisation of fire fighting stairs Pressurisation systems should conform to the requirements of EN 12101-6:2005 WHY PRESSURISE?

  6. BS 9999: 2008 recommends Pressurisation (designed to EN12101-6) to: Replace separation of dead end corridors with a fire door Replace protected lobbies in single stair buildings, buildings over 18m, buildings with phased evacuation and buildings where a stair has not been discounted in the sizing of escape widths Allow a single stair to extend down to a basement fire fighting shafts over 10m deep and over 30m tall (Class B) WHY PRESSURISE?

  7. INSTALLATIONS West India Quay, London Oxford Road, Leicester

  8. INSTALLATIONS Beetham Tower, Birmingham Holiday Inn Express, Hull

  9. EN 12101- 6 BUILDING CLASSIFICATION

  10. BASIC PRINCIPLES The system must protect against smoke entering the stairs or travelling between storeys via lifts accessed from protected lobbies The intent is to have the highest pressure in the stairs and a reducing pressure gradient through to the accommodation All ‘pressures’ described are actually pressure differentials to the accommodation

  11. BASIC PRINCIPLES All pressurisation systems require 3 basic components: A means of supplying clean air to pressurised areas A means of ensuring excessive pressure differentials do not occur A means of relieving pressure from the accommodation

  12. WHICH AREAS DO WE PRESSURISE? The first decision to make for any system Depends upon class of pressurisation Depends upon building layout Is there a lift? Where is suitable for accommodation air release

  13. STAIRS (WITH SIMPLE LOBBY) Pressurise the stairs only. Only used where the staircase is entered via a simple lobby (i.e. a lobby without lifts or other possible escape route) or directly from the accommodation. Stairs Simple lobby +ve Air supply Accommodation

  14. STAIRS, LOBBY & LIFT Pressurise stairs and lobbies. Used to extend protection to lobbies: Lift +ve Accommodation Air supply +ve Stairs

  15. STAIRS, LOBBY & LIFT Pressurise stairs, lobby and lift. Generally only used in fire fighting – Class B +ve Lift +ve Lobby Accommodation Air supply +ve Stairs

  16. WHAT PERFORMANCE IS REQUIRED? Depending upon the class of system we have set criteria to achieve: Pressure differentials – all doors closed: 45 – 50 Pa Velocity through open door on fire floor: 0.75 – 2.0 m/s Pressure differential – doors open on floors other than fire floor: 10 Pa

  17. CLASS A - DOORS CLOSED Duty Pressure relief damper /standby fan FIRE FLOOR (LOBBY/CORR) 50Pa Automatic air release (above ventilator accomm odation) Ductwork Smoke detector system Door opening force not to exceed 100N Stairs First floor Ground floor

  18. CLASS A - DOOR OPEN Duty Pressure relief damper /standby fan FIRE FLOOR (LOBBY/CORR) Accommodation air release 0.75 m/s average velocity ventilator Ductwork Smoke detector system Stairs First floor Ground floor

  19. CLASS A: MoE - Defend in Place Do not attempt to pressurise the corridors up to dwelling front doors Provide air release from the corridor or lobby Long corridors will be fitted with smoke seal doors - air release needs to be on stairs side of nearest doors

  20. CLASS A CLASS A Accommodation Air release via ventilator Air release via shaft

  21. CLASS B: FIRE FIGHTING STAIRS Requirement for stairs set by ADB BS 5588-5 or BS 9999 Pressurised lobbies essential Lobbies may contain fire fighting lift, which also needs to be pressurised

  22. CLASS B - DOORS CLOSED Duty Pressure relief damper /standby fan Supply to stair, lift and lobby 50 Pa 45 Pa FIRE FLOOR above above accomm accomm Accommodation air release odation odation ventilator Ductwork Smoke detector system Door opening force not to exceed 100N Stairs First floor Ground floor

  23. CLASS B - DOORS OPEN Duty Pressure relief damper /standby fan FIREFLOOR 2 m/s average velocity Accommodation air release ventilator Ductwork Smoke detector system Lift door open if fitted Stairs First floor Ground floor

  24. * Pressurising these spaces is at the discretion of the system designer

  25. CLASS C - DOORS CLOSED Duty Pressure relief damper /standby fan Accommodation air release 50Pa above ventilator FIRE FLOOR accomm odation Ductwork Smoke detector system Door opening force not to exceed 100N Stairs First floor Ground floor

  26. CLASS C – EXIT DOOR OPEN Pressure relief damper Duty /standby fan 10 Pa FIRE FLOOR above accomm Accommodation aor release odation ventilator Ductwork Smoke detector system Stairs First floor Ground floor

  27. CLASS C - DOOR OPEN Pressure relief damper Duty /standby fan FIRE FLOOR Accommodation air release 0.75 m/s average velocity ventilator Ductwork Smoke detector system Stairs First floor Ground floor

  28. EQUIPMENT Fans ambient rated duty + standby (or standby motor) if only one MOE route; usually in series to save space One fan set may supply stairs, lobbies and lift shaft not usually attenuated unless needed for test periods In 1 hour fire rated enclosure or roof Power supplies primary + secondary Mains + generator or separate mains supply Pressure relief usually gravity damper in stair inverter control of fans possible but difficult due to response speed requirement

  29. EQUIPMENT Ductwork separate vertical ducts for stair, lobbies, lift shaft ambient rated unless breaching fire compartmentation Builders work shafts are suitable if well sealed VCD required at each tee and grille for balancing Two separate inlets facing different directions with smoke detector operated inlet dampers if at roof level – 5m away from any smoke exhaust Grilles one per 3 storeys in stair one per lobby one per 30m in lift shaft

  30. EQUIPMENT Volume control dampers on each section of ducting Twin air intakes on separate facades of the building with motorised dampers and smoke detector control

  31. EQUIPMENT Accommodation air release by leakage, ventilators, natural or mechanical shaft leakage can be from building fabric, HVAC ductwork, permanent trickle vents, but not window breakage ventilators must be provided on at least 2 sides, discount the side with the largest vent area (2.5m/s) Natural shaft terminations need to be located to minimise adverse wind effects (2m/s) Mechanical shafts should operate whenever the pressurisation system does and should not cause excess pressure differentials

  32. CONTROLS Initiation – From automatic fire detection system Needs to identify fire floor Locate detector close to door to pressurised space Class B initiation Can be manual switch from MOE state or direct from automatic fire detection system Accommodation air release only opened on fire floor (to prevent risk of fire/smoke spread) Fire fighter controls provided at base of stair

  33. BASIC PRINCIPLE Pump air into a ball or a tyre and we have a positive pressure inside If there is a puncture then to maintain a positive pressure we need to keep pumping air in For a given pressure and a given puncture size we will require a fixed rate of air input to balance the air lost through the puncture

  34. BASIC PRINCIPLE From Bernoulli’s equation: P = 0.5   ( Q2/A2 ) Rewriting and correcting for effective area Q = 0.83  (A P0.5 ) Q is the leakage rate from the pressurised space that we need to balance with supply air

  35. BASIC PRINCIPLE Easy in principle but we have a complex network of leaks and conditions to fulfil Therefore the calculation becomes complex EN 12101-6 devotes a 12 page annex to this

  36. DUCT SIZING Select duct layout and dimensions Calculate resistance of ductwork The operating pressure of the system should be added to the ductwork resistance Size fans to provide the design flow rate at the total pressure

  37. PROBLEMS Design process requires: an assessment of the build quality and an allowance for additional unidentified leakage – this is in effect a ‘guess’ Loose, average or tight construction will affect the leakage rates used in calculation add 50% safety margin + 15% margin for duct leakage + 20% duct pressure loss margin There is often a temptation to reduce the allowances at design stage – this can lead to problems at completion of the project when pressures/velocities cannot be achieved.

  38. Check equipment is installed as per design Carry out normal mechanical and electrical checks Carry out performance tests, but first: All doors must be fitted and close properly All finishes must be complete - carpets laid etc All false ceilings must be in place There must be no temporary openings or unsealed service penetrations COMMISSIONING

  39. EQUIPMENT CHECKLIST - Main power supply and standby supply - Duty and standby fan - Automatic change over - Fan located in protected area - Fan Inlet protected from effects of smoke - Smoke detection provided adjacent to lobby/accommodation door - Manual override provided - Supply point located at every 3 floor levels - Pressure relief damper provided in stair - Venting provided from accommodation - No smoke seals provided on doors

  40. While the test method aims to neutralise the effects of wind, testing on windy (and especially blustery) days should be avoided if possible A pre-test inspection is recommended to identify potential problems that can be rectified prior to actual test Out of hours testing is highly recommended On day of test, ensure all other H&V systems are shut down PERFORMANCE TESTING

  41. PRESSURE DIFFERENTIAL MEASUREMENT TECHNIQUES • Requires a manometer and 2 long flexible tubes • Locate end of one tube in the accommodation and the other in the pressurised space, both away from draughts and at least 50mm above floor • Manometer then reads pressure differential directly 51

  42. Pressures On each floor in turn open all doors, allow them to close and then measure the pressure differential across each relevant door Measure the opening force required on each relevant door at the door handle PERFORMANCE TESTING

  43. AIR VELOCITY MEASUREMENT TECHNIQUES • Requires a rotating vane anemometer • Standing to one side (out of air stream) place anemometer in the plane of the door • Measure flow rate at 8 locations spread evenly • Do not move the anemometer during readings • Take arithmetic average of readings

  44. Velocities On each floor in turn open doors as specified in EN 12101-6 and measure average air velocity For classes C, D, E on each floor in turn open doors as specified in EN 12101-6 and measure pressure differential between stair and accommodation Adjust system as necessary and retest until all pressures and velocities are correct PERFORMANCE TESTING

  45. The procedure is simple, but in practice: Excessive leakage is often a problem and can lead to a need for multiple commissioning visits and arguments with the builder Testing and balancing large systems can be very time consuming, especially with pressurised lobbies PERFORMANCE TESTING

  46. THE FUTURE A CEN committee is currently revising EN 12101-6 Proposals are: Delete ‘kit’ references and CE marking Simplify system requirements Reduce costs Not likely to be published until 2011

  47. The EndAny Questions?

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