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7Section
HVAC Products forthe Nuclear andDefence Industries
Introduction
Wozair (abbreviated in 2000 fromWaterloo-Ozonair Limited) has beenclosely associated with the Nuclearindustry for many years. The word“Safechange®” was first registered byOzonair in the 1960’s.
An extensive range of ventilationproducts is available, both for C1 andC2 supply systems and C3, C4 andC5 contaminated extract systemswhere safety and reliability are ofparamount importance. The range ofproducts includes:
• Safechange® Filter Units (Radialand Axial Flow)
• Mobile Filter Units (Radial and AxialFlow)
• Dampers including Fire, Control,Isolation and Non Return types
• Fully Integrated Plant Rooms
• Air Handling Units
• Quickmix Injectors
• Other Products such as Louvres,Moisture Eliminators and Grillesavailable from the Wozair Offshoreand Marine range
• Ancillary equipment such as FilterChange Trollies and Bag Sealingmachines
• Recommended spare parts suchas Safechange® Bags and HEPAFilters
7 HVAC Products for the Nuclear and Defence Industries
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In house manufacturing systems andprocedures are in place to ensurequality, safety and reliability including:
• Detailed design, engineering and3D CAD drafting
• Full CAD/CAM laser cutting up to12mm stainless steel and 20mmcarbon steel
• Synergic MIG welding and TIGwelding to BNFL approvedprocedures
• Dye Penetrant non destructivetesting
• Pressure containment testing –positive and negative up to 10kPa
• Blade leakage testing
• AHU performance testing –volumetric and pressure
• Full documentation serviceincluding life time records, materialtraceability etc
In addition X Ray and MPI nondestructive testing, structuralcalculations and seismic evaluationcan be carried out using approvedthird parties
Wozair is approved by all thelicensed UK Nuclear operators andhas an extensive track record ofsupplying equipment to the followingsites:
• Dounreay• Sellafield• Trawsfynydd• Dungeness• Aldermaston• Winfrith• Capenhurst• Devonport• Risley• Porton Down• Heysham• Bradwell• Harwell• Burghfield
7 HVAC Products for the Nuclear and Defence Industries
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7Section
Safechange® HEPAFilter Units
Introduction
A range of radial and axial flowSafechange® HEPA Filter Units for usewith HVAC extract systems whereradioactive or other toxic effluents maybe present. The designs are such thatthe High Efficiency Particulate Air(HEPA) filter can be changed withoutthe risk of contamination to personneland the environment.
The range is available in eitherstainless steel or painted carbon steelwith a Decontamination factor inexcess of 2000.
Range
• Radial flow single filter housings75l/s to 950l/s
• Radial flow multiple filter housings
• Axial flow single filter units including pre filters as required
• Manifolds for radial flow single units or axial flow housings • Butterfly dampers, Isolation valves, depression relief valves and filters
• PVC Safechange® Bags
• HEPA Filters & Spark Arrestors
Single Filter Radial FlowHousingsDesigned to accept a single radialflow filter to AESS 30/95100, thehousing is designed to be inaccordance with NF0153/1.
Units are available as all weldedstainless steel (304 or 316 grade) orpainted carbon steel construction.
Inlet and outlet flanges shall beprecision laser pierced for connectionto clients ductwork, isolation valves ormanifolds, please refer to Section 11for details. Inlet/filter spigots areaccurately machined and welded inposition.
Casing and outlet spigots are rolledand welded from 2mm thick materialcomplete with two swaged grooves forattachment of filter bags.
Removable access cover accuratelyspun from 2.5mm material and fixed tothe casing flange by machined swingback handles and with 80mmcruciformed handwheels.
7.1 Safechange® HEPA Filter Units
The cover is sealed to casing with achloroprene ‘O’ ring (55 IRHD).
A standard 50mm welded socket andplug is fitted for depression reliefconnection, and also two 6mmmanometer connections.
Filter Housings can be supplied onsupport legs to typically raise thecentre line to 1500mm. However witha 950l/s HEPA Filter weighing 18kgs itis recommended that a scissor liftchange trolley is used to assist withmanual handling.
HEPA Filters are available at 75, 160,280, 470 and 950l/s. When combinedonto manifolds with individual housinginlet and outlet Isolation dampers thecapacity of an extract system can beincreased in multiples of 950l/s.
It is normal for these arrangements toinclude 2, 3, 4, or 6 housings althoughmore can be accommodated. Forminga bank of HEPA filters with one 950l/sspare capacity enables contaminatedfilters to be individually isolated andchanged without shutting down theextract fan system.
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7.1 Safechange® HEPA Filter Units
Multiple Filter Radial FlowHousings
Designed for supply to BNFL theseunits are suitable for multiples of 950l/sradial flow filters to AESS 30/95100.
Units can be supplied for 2, 4, 6 or 8filters with various horizontal or verticalconfigurations to suit requirementsand are designed to be in accordancewith NF0153/1.
The units are available in eitherstainless steel (304 or 316 grade) orpainted carbon steel construction.
The unique feature of the Wozairrange is the robust fully weldedconstruction which guarantees theintegrity of the housings without havingto rely on gasketted panels.
The range has been seismicallyevaluated by Alsthom for use atSellafield site and has beensuccessfully leak tested at pressuresof up to 20kPa.
Inlet and outlet flanges are arranged tosuit requirements and can be circular,rectangular or square and positionedon any of the two sides, top, bottom orback of the unit.
The fully welded filter partition plate isa single piece with accuratelymachined 350mm diameter filterspigots welded in position.
The front plate consists of weldedspigotted openings with 625mmdouble bag grooves for access to thefilters.
Removable access covers accuratelyspun from 2.5mm material areprovided for each opening. These arefixed to the housing by machinedswing back handles with 80mmcruciformed handwheels.
The covers are sealed to the casingwith chloroprene ‘O’ rings (55IRHD).
Flanged depression relief connectionsare provided for either 470l/s (150mmflange) or 25l/s filters (100mm flange)as required.
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7Section
Axial Flow Filter HousingsAxial flow Safechange® filter housingsare available in painted mild steel orstainless steel grade 304L or 316L.The housings are generally 2 mmthick, and are of fully weldedconstruction.
The mild steel option is supplied shotblasted and painted with a 2 packepoxy system and stainless steeloption acid pickled and passivated.
The housing incorporates inlet and outflange connections and a bag changespigot, welded as an integral part ofthe housing and incorporating twogrooves for filter bag retaining bands.
The HEPA filter housing is designedfor a HEPA filter nominally 610 x 610mm square x 298 mm deep, witheither a maximum rated capacity 0.94m3/s or 0.47 m3/s. The inlet face of thefilter is fitted with a gasket that sealsagainst an internal lip within the filterhousing.
Where required a pre-filter housingcan be provided which is designed fora panel filter nominally 610 x 610 mmsquare x 50 mm deep. The inlet faceof the filter is fitted with a gasket thatseals against an internal lip within thefilter housing.
A removable cover allows access toremove and replace the HEPA or pre-filter. The front face of the access coveris fitted with two ‘goal post’ typehandles. Access covers are fitted withfour slotted brackets andcorresponding pivoting hand wheelsare provided with the bracket weldedto the front plate.
Hand wheels are duraplast 80mmdiameter cruciform type, manufacturedwith an extended steel boss. Areplaceable cover gasketmanufactured from 55 IRHDchloroprene is provided for sealingthe cover onto the housing assembly.
7.1 Safechange® HEPA Filter Units
Each filter housing incorporates twostainless steel cam bars that aremanually rotated throughapproximately 90°. These force thefilter cell against its sealing lip in oneposition and allow removal of the filterin the second position. The removablecover can only be fitted when the filteris in the sealed position.
The filter housing is designed forvertical downward airflow althoughother orientations can be considered.
Should multiple housings be requiredas determined by the duty inlet andoutlet manifold sections can beprovided in order that the housingsform part of a complete assembly.
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Associated Equipment andProducts
ManifoldsInlet and outlet manifolds aredesigned to bank together a numberof filter housings where an increaseddesign airflow rate is required.
Manifolds are available in painted mildsteel or stainless steel grade 304L or316L. Design and construction is inaccordance with the nuclear ductworkspecification normally NF0154/2 or 3(previously AESS 6008).
The mild steel option is supplied shotblasted and painted with a 2 packepoxy system, and stainless steeloption acid pickled and passivated ormanually cleaned as size permits.
Inlet and outlet flanged connectionsare supplied for connection to clientsductwork. Complete filter banks will beassembled with gaskets andfasteners at works and pressuretested.
SupportsEither individual or manifoldedSafechange® housings can besupplied with rigid mounting framesfor ease of installation at site.
Individual Safechange® housings canbe specified with welded support legsto raise the filter centre line to asuitable working height for example1500mm. The support legs willgenerally be 50mm angle eitherpainted mild steel or stainless steelas the housing.
Manifolded housings can be mountedon a rigid cantilever structuredesigned to support the weight ofhousings, manifolds, dampers andancilliary equipment. The supportstructure will be fabricated fromwelded and bolted mild steel channeland angle sections, hot dip galvanisedto EN1461.
Lifting lugs and bolting down pointsare provided for installation on site.
Inlet and outlet HousingIsolation DampersFor details please refer to Section 7.2of this catalogue.
Depression Relief SystemsNuclear extract systems normallyoperate under negative pressure, sothat to permit a filter change bag inbag out operation, it is necessary toprovide a depression relief system onthe clean side of the main HEPA filter.This facility comprises an isolationvalve and a disposable HEPA filter toprotect operators and the environmentfrom any possible backflow
Each Wozair single filterSafechange® housing is provided witha 50mm welded socket for connectionto a 5l/s depression relief valve andfilter system. With Multiple FilterHousings the connection maybeincreased to 100mm flanged for 25l/sdepression relief valve and filter.
Isolation valves will normally bediaphragm type for 50mm and butterflytype for 100mm.
Depression relief HEPA filters aresupplied manufactured in accordancewith AESS30/93450
Valves and filter can either be providedloose for client installation on site orpiped together and supplied fitted onone side of the Safechange® housing.
PVC Safechange® BagsFor the safe handling and disposableof contaminated filters WozairSafechange® housings are providedwith a double sealing groove for fittinga PVC bag.
Wozair Safechange® bags aremanufactured from 250 micron thickPVC and feature a rubber sealingband and hand glove pockets for easeof removal of a contaminated filter
HEPA Filters, Pre Filters andSpark ArrestorsPlease contact our sales office.
7.1 Safechange® HEPA Filter Units
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7Section
Dampers
Introduction
To supplement the comprehensiverange of offshore and marinedampers detailed in CatalogueSection 3 Wozair offer a full range ofhigh integrity HVAC dampers for thenuclear industry consisting ofisolation, balancing, control, nonreturn and smoke/fire dampers.
Dampers are designed generally inaccordance with BNFL specificationNF 0155/1 and AWSS 12023. They areavailable to meet the requirements ofductwork specification NF 0154/1, 2 &3 (previously AESS 6008).
Range
Isolation DampersDesigned for tight shut off and willnormally be fully open or fully closed.Airflow through the damper can be ineither direction and the dampers canbe installed in any orientation.
Operation can be specified asmanual, electrical actuation orpneumatic actuation. Manualoperation is not recommended forinaccessible or hazardous areas.
Dampers can be supplied asopposed blade rectangular type. Forcircular ductwork dampers can besupplied either as single bladebutterfly type up to 400mm diameter orabove this size square with transitionplates and flanged spigots.
Balancing DampersDesigned to achieve the required airdistribution and can be set at anyposition between open and closed.Balancing dampers are designed formanual operation with the airflow ineither direction. They can be installedin any orientation. Dampersincorporate an external quadrant,handle and locking arrangement toenable setting in position oncecommissioning and balancing hasbeen completed.
Control DampersSimilar in function to a balancingdamper although the damper can beautomatically adjusted to a requiredposition by the use of an electric orpneumatic actuator coupled to apositioner.
7.2 Dampers
Non Return DampersThese dampers are designed to allowairflow in one direction only. Uponbackflow the dampers will close andisolate the system.
Smoke and Fire ControlDampersDesigned to prevent the spread ofsmoke or fire through an airdistribution system, these damperswill normally be located at fire wall orfloor penetration points.
Fire dampers have beenindependently tested to BS476: Part20 and are certified by Lloyds for bothhorizontal and vertical positions.
Dampers are suitable for airflow ineither direction and will operate in anyorientation.
Fire dampers shall operate to close byoperation of the thermal trigger,remote sensor or failure of the electricor pneumatic supply.
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Ductwork ApplicationNF 0154 Part 1
For low integrity installations for nonactive areas where the ductwork ismanufactured to DW144 galvanisedsheet.
Damper frames and blades aremanufactured from galvanised sheetsteel with laser pierced and formedflanges. Frames are welded acrossthe flanges and riveted and sealedalong the duct.
Blades are fixed to steel spindleswhich rotate in oil impregnatedsintered bronze bearings.
Spindles are linked together outsidethe casing to give opposed or parallelblade motion as required.
As this construction does not providefor spindle seals the linkage ispermanently fixed by welding.
Ductwork ApplicationNF 0154 Part 2
For high integrity installations wherethe ductwork is manufactured frommild steel with all welded seams andflanged joints, suitable fortemperatures up to 100°C andworking pressures of 6000Pa and airvelocities of up to 15m/s.
Damper frames and blades aremanufactured from mild steel hot dipgalvanised or stainless steel grade304L or 316L with laser pierced andformed flanges. Frames are fullywelded across the flanges and alongthe duct.
Blades are plug welded to continuoussteel spindles which rotate in oilimpregnated sintered bronzebearings. Drive end bearings arethrough type with removable lip seals.Non drive end bearings are sealed forlife. Spindles are linked togetheroutside the casing to give opposed orparallel blade motion as required.
Linkages and pins are manufacturedfrom 316 grade stainless steel andare pinned and removable formaintenance of the lip seals.
Fabrication of the dampers will becarried out in accordance withstandard in house procedures.
7.2 Dampers
Ductwork ApplicationNF 0154 Part 3
For high integrity installations wherethe ductwork is manufactured fromstainless steel with all welded seamsand flanged joints, suitable fortemperatures up to 100°C andworking pressures of 6000Pa and airvelocities of up to 15m/s.
Damper frames and blades aremanufactured from stainless steelgrade 304L or 316L with laser piercedand formed flanges. Frames are fullywelded across the flanges and alongthe duct.
Blades are fixed to stainless steelspindles which rotate in oilimpregnated sintered bronzebearings. Drive end bearings arethrough type with removable lip seals.Non drive end bearings are sealed forlife.
Spindles are linked together outsidethe casing to give opposed or parallelblade motion as required.
Linkages and pins are manufacturedfrom 316 grade stainless steel andare pinned and removable formaintenance of the lip seals.
Fabrication of the dampers will becarried out in accordance withfabricationprocedures approved to NF 0081Parts 1 and 5.
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7Section
Operating Modes
Manual OperationDampers are provided with a multipleposition lockable quadrant and ahandle connected to the drive shaftwith sufficient clearance for handoperation.
Spring Loaded LatchingDampers are held in position by atrigger arrangement which operates ata preset temperature (68°C).Alternatively the damper can belatched open by an electrio magnetwhich releases when a signal from asmoke detector or sensor is received.
Electric OperationOperation shall be provided by aquarter turn electric actuator, such asBelimo, mounted on a plate andconnected to the drive shaft. Theactuator can be specified as 24v dc,110v ac or 240v ac. The actuator willinclude integral status switches toprovide remote indication of damperopen/closed status and an externalpointer. Normally the actuator leadswill be provided loose although ifrequired a termination box can besupplied mounted on the dampercasing. A manual override will beprovided as required.
Pneumatic OperationDampers shall be provided as springreturn or stay put type as required.Spring return actuators, such asHytork, shall be suitable for 4 to 8 bargsupply and shall return to the defaultposition; damper either open orclosed in the event of loss of supply.
Alternatively a double acting actuatorcan be supplied which will stay inposition upon loss of supply.
Each damper shall be provided with aswitch box containing limit switches togive remote indication of open orclosed status. The switch box shall beprovided as part of the actuatorassembly for client connection via M20ISO entries. It will also include localvisual indication of damper status.
The actuator assembly shall also beprovided with a close coupledsolenoid valve which shall cause thedamper to operate (open or closed)when energised. Failure of theelectrical supply shall either cause thedamper to return to the default positionor stay put as required. Solenoidvalves can be provided for 24v dc, 110vac or 240v ac.
If required pneumatically operateddampers can be provided with a backup air reservoir and non return valve.
Performance and Testing
Casing LeakageDamper casing leakage will be inaccordance with the applicableductwork classification NF 0154/1, 2 or3 (previously AESS 6008) at thespecified duct pressure. As standardall Wozair dampers for NF0154/2and 3 ductwork systems will be 100%case leak tested at 3000Pa to
7.2 Dampers
demonstrate a maximum leakage of0.5% enclosed volume per hour. Foradditional security all case welds aredye penetrant non destructive testedand certified.
Blade Leakage
Rectangular Isolation DampersLess than 0.040 m3/s per m2 damperface area at 2000 Pa
Butterfly Isolation DampersLess than 1l/hr per m2 damper facearea at max working pressure up to10000 Pa.
Fire DampersLess than 0.040 m3/s per m2 damperface area at 2000 Pa.
Non Return DamperLess than 0.1 m3/s per m2 damperface are at reverse differentialpressure.
Balancing dampers and controldampers will not normally be specifiedwith a blade leakage requirement.
Pressure Drop
Isolation dampers and fire dampersfully open at 10m/s cause a staticpressure drop of 18Pa.
Balancing and control dampers fullyopen at 10m/s cause a static pressuredrop of 15Pa.
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7.2 Dampers
Butterfly IsolationDamper
Typical Applications
A range of high integrity dampers hasbeen designed to meet therequirements of the nuclear industry,where low case leakage, corrosionresistance and mechanical integrityare of prime importance.
The following design features havebeen included:• Continuously welded construction• Single blade• Low casing leakage• Low blade leakage• Low airflow resistance• Low noise generation• Manual, pneumatic,
or electric operation• Wide range of materials• Excellent corrosion resistance
Description
Rolled casing manufactured from1.5mm minimum thick material, withwelded seam, length over flangesminimum 100mm. Welded flanges 25x 6mm thick drilled to standard nuclearspecification pattern. A single 2mmthick circular butterfly blade with a onepiece neoprene seal, bolted to 19mmdiameter shaft that rotates in sealed‘oilite’ bearings. The shaft is extendedon one side for actuator mounting.
Control MechanismManual Isolating Damper: This isoperated by a robust adjusting handlewith a locking device which movesacross a quadrant plate. Moving thehandle through 90º moves the bladefrom the fully open to the fully closedposition, thereby enabling the unit tobe used for volume control purposes ifnecessary.
Pneumatic and Electric Options:These are operated by actuatorswhich move the blade from the fullyopen to fully closed position.
Micro-switches, indicating bladeposition are also available. Theseunits are designed to be fully open orfully closed.
Leakage RatesThe isolation damper has beendesigned to minimise leakage withthe blade in the closed position.Extensive testing on 350 diameterNuclear HEPA filter Isolation Dampershas indicated a mean leakage rate of0.0001 m³/sec at a differentialpressure of 10,500Pa. Specificrequirements regarding leakageshould be discussed with Wozairengineers.
Ordering
Quantities, surface finish and otherspecial requirements to be statedseparately.
Type BID Duct Dia 356Ø
Material 316L Case Depth 100D
Type Wozair: Butterfly ManualIsolation Damper
Case Material:Stainless SteelLow Carbon 1.4307 (SS304L) = 304LLow Carbon 1.4404 (SS316L) = 316LMo>2.5% 1.4432 (SS316L) = 316L
Case Thickness: 1.5mm
Nominal Clear inside duct dimensionsDuct Size: ‘Quote’ inside Diameter
Order Code Example:BID/316L/1.5/356Ø/100D
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7Section
Supply Air HandlingUnits
Introduction
Wozair manufacture and supply highintegrity Air Handling Units for theNuclear Industry. Both draw throughand blow through units are available.Units are designed for use in exposedcoastal areas typical of power stationlocations with a 40 year lifeexpectancy. Units are manufactured tocomply with NF specifications andspecific site requirements makingmost units unique. In addition todesigning the Air Handling Unit as themain supply plant it can also performthe function of a pressurisation unit.
Units incorporating centrifugal fansare designed with the fans containedwithin a panelled crate.
Units are generally designed to belifted and positioned as one completeassembly so as to minimiseinstallation time. However if requiredthey can be supplied in modularformat for re-assembly on site.
The main features and components ofan Air Handling Unit are presentedherein.
Standards
Wozair design and manufacturer AirHandling Units to comply with NF andAWE specifications and EC directives.
Units comply with Directives and anyamending Directives:Machinery Directive 98/37/ECLow Voltage Directive 73/23/EECATEX Directive 94/9/ECEMC Directive 89/336/EECPressure Equipment Directive 97/23/EC
Skid
The Air Handling Unit is supplied as askid mounted assembly with the skidfabricated from hot rolled structuralsteel sections. The skid can bedesigned to BS 449 and withconsideration for transportation forcesand any seismic conditions. Skids arewelded by coded welders and hot dipgalvanized to EN 1461 aftermanufacture. If required main weldscan be subject to NDT. Lifting lugsand earthing points are provided.
7.3 Supply Air Handling Units
Casing
The casing consists of a rigidconstruction framework with laggedinfill panels for thermal insulation andnoise attenuation.
The frame work is continuouslywelded and manufactured fromstainless steel grade 1.4404 (316L) or1.4307 (304L). The frame work is 1.5mm, 2.0 mm or 3.0 mm dependantupon the size and application. Ifrequired the frame work can beinsulated with a closed cellelastomeric material or mineral woolto eliminate a heat bridge.
Infill panels are double skinned andflush mounted. Infill can be 25 mm or50 mm thick and is used to providethermal insulation and noiseattenuation. Infill material can beextruded polystyrene rigid boardbonded to the panel skin or mineralwool. Panel skins are manufacturedfrom the same material as the framework with a range of sheetthicknesses available from 0.9 mm to2.0 mm. Hinged access panels areprovided for inspection andmaintenance of equipment.
A baseplate manufactured from thesame material as the frame work issandwiched between the frame workand the skid and is insulated ifrequired.
Externally mounted units can beprovided with a pitched roof to shedrain.
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Fans
Fans are typically of the DIDWcentrifugal type to NF0152/1 with non-stalling and non-overloadingcharacteristics. Fans are generallybelt driven although direct drive fanscan be provided for operation withvariable speed drives.
The fan casing can be gas tight to therequirements of NF0152/2manufactured from mild steel (type B)or stainless steel (type D). Impellerscan be mild steel painted or stainlesssteel as appropriate.
Fans are driven by LV motors. Wherebelt drive is employed, belts are ananti-static, vee design. The motor ismounted on a frame integral to the fanset. The fan is isolated from the AirHandling Unit by anti-vibration mountsand flexible connections.
If required Wozair can supply fanssuitable for operating within a zone 1or zone 2 motors hazardous area andas such the fans shall incorporateanti-spark features.
Fans can be provided with thefollowing accessories: speed sensor,bearing monitoring, extendedlubricators, automatic greaselubricators, drain plug, access door,inlet and discharge guards and beltguards.
Air Handling Units can be designedwith 100% run and standby fan sets or2 x 50% fan sets or run and standbymotors on a single fan. With dual fanarrangements fans are installed inseparate chambers to enablemaintenance on one fan to be carriedout whilst the other is in operation.These chambers can be configuredside-by-side or one above the othersubject to practical transportationlimits. Inlet guide vane, manual orautomatic isolation and non-returndampers can be provided to controlthe airflow and isolate the fanchamber.
Motors
These are in accordance with NF0004/1, NF0004/2, NF0004/2, NF0032/1, BS4999 and BS 5000 suitable for directon line starting and operating on 415V.If required we can supply motor tooperate on any common 3 phase lowvoltage supplies of 50 Hz and 60 Hz.
If required Wozair can supply motorsrated suitable for use in a potentiallyhazardous area as required andcompliant with project specificationsand standards where stipulated.
Cooling Coils
Cooling coils can be selected tooperate with refrigerant or chilledwater. Tubes are typically seamlesscopper and are expanded on to copperfins although aluminium fins areavailable. Copper fins may be pre-tinned or copper tube and fin coilselectro-tinned after manufacture.Alternatively with copper tube and fincoils or copper tube and aluminiumfins a PolyAl anti-corrosion treatmentcan be provided.
7.3 Supply Air Handling Units
As a general rule where the facevelocity on the cooling coil exceeds 2.5m/s a vane eliminator should beinstalled to prevent moisture carry-over. Vane eliminators can besupplied in stainless steel 316,marine grade aluminium or polymers.
The cooling coil section of the AirHandling Unit is provided with a draintray to drain to the edge of the skid.
Temperature control valves can besupplied as required.
Heating Coils
These shall generally be as describedabove but suitable for operation withsteam, hot water or a heating medium.Some applications may demand theuse of stainless steel tube.
Electric Heaters
Electric heaters are designed forthyristor or step control. Generallyelements are 80/20 nickel/chromeresistance wire insulated withcompacted magnesium oxide andceramic beads in Incoloy 800 sheaths.Thermocouples, RTD’s or thermostatsare installed to detect element and airover temperature. Elementtemperature is normally restricted to150 - 200ºC.
If required heaters can be suppliedsuitable for operation in a potentiallyhazardous area but any manual orauto reset device operated inconjunction with the over temperaturesensor should be located in a controlpanel in a non-hazardous area. Theelements are terminated in astainless steel enclosure.
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7Section
Filters
A wide selection of panel and bagfilters is available to suit a range ofapplication such as removal of dust orcoalescing filters for the removal ofparticulate salt to reduce theconcentration to less than 0.05 ppm. Ifrequired HEPA filters can beincorporated within the Air HandlingUnit.
Filters are arranged on mountingframes within the unit to suit side orfront withdrawal. Instrumentation canbe provided to monitor the filtercondition during operation such as adifferential pressure gauge, switch ortransmitter.
With coalescing filters vaneeliminators can also be provided toprevent moisture carry-over. Vaneeliminators can be supplied instainless steel 316 or marine gradealuminium.
Humidification
Electrically operated fresh steamhumidifiers may be installed ifrequired. Alternative humidifier typescan be considered upon request. Thehumidifier, including its water tank andsteaming chamber form part of theunit package, space permitting. Amatrix of injection tubes is installedwithin the unit case as they provide thebest solution for achieving theminimum absorption distance. Thehumidifiers are supplied with a controlpanel and can be suitable for thyristoror step control. It is preferable tolocate humidifiers within a non-hazardous area.
Weather Louvres
For an exposed fresh air intake aweather louvre can be provided, ifrequired, to prevent the ingress of rainwater into the Air Handling Unit inlet.
7.3 Supply Air Handling Units
Control Dampers
In addition to the dampers previouslydescribed in the fan section controldampers at the Air Handling Unit inletor discharge can be supplied.Dampers can be used to isolate theunit, regulate the airflow or in the caseof a unit drawing in a mixture of freshand re-circulated air, modulatingcontrol dampers to vary the mix ratio.Modulating dampers can be providedwith pneumatic, electro-pneumatic orelectric positioners suitable for ahazardous or non-hazardous area.
Controls/Wiring
Control panels can be providedinstalled on the unit skid or suppliedloose. The design and features ofeach panel is dependant upon theapplication and requirements. Controlpanels can be provided for installationin a hazardous area though it isrecommended that wherever possiblethey are located in non-hazardousarea.
Wozair can provide heater thyristorcontrol panels, variable speed drivesand HVAC control panels to suitcustomer requirements.
Electrical components on the AirHandling Unit shall generally becabled to a terminal box mountedexternal to the unit.
Cabling shall as minimum be flameretardant PVC with options to providelow smoke, zero halogen cable bothunarmoured and armoured. Cablingcan be run in cable tray as required.Earthing continuity is achieved bycabling equipment to a commonearthing point on the unit skid base.Cable penetrations into the unit are byway of gland plates or transit frames.
Safety Features
The units are provided with an ECDeclaration of Incorporation. Wherepersonnel can gain internal access tomaintain filters, dampers, fan sets orother equipment then lights of thefilament or fluorescent type areprovided operated from a commonswitch. For the fan motor a pushbutton emergency stop can be fitted.As required any electrical componentsshall be suitable for use in ahazardous area.
Ancillary Components
The following features can beprovided:• Temperature, pressure and
humidity instrumentation• Test points• Interface junction boxes• Maintenance beams to lift and
move motors, typically 15 kW andabove
• Spreader beams with shackles forlifting and positioning the units onsite
• Access platforms and ladders forequipment at high level
• Drain traps and pipes• Trace heating of drains
Testing
Various testing options are availableon the completed Air Handling Unitincluding:Running motors on project specifiedvoltage and frequency 50Hz/60HzVolume/pressure testing based on BS6583Case deflection and leakage basedon EN 1886Case leakage testing up to 3000 PaIndicative noise breakout testingMeasurement of the fan runningspeedRecording motor running current
Leakage performance of Wozair AirHandling Units meets DW143 Class Bwhere the leakage from the casing iscalculated as:Leakage (l/s/m²) = 0.009 x testpressure0.65
7Section
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Extract Fan Skids
Introduction
Wozair manufacture and supply highquality Extract Fan Skids to the NuclearIndustry. Units are designed for use inexposed coastal site locations typicalof Power Station locations with a 40year life expectancy. Fan Skids aremanufactured to comply with specificclient and site requirements.
Fan Skids Units are typically designedwith centrifugal fans. Units can bedesigned with: a single fan, 100% runand standby fan sets, 2 x 50% fan setsor run and standby motors on a singlefan.
For low integrity systems with dualDIDW the fans are contained within apanelled crate and are installed inseparate chambers to enablemaintenance on one fan to be carriedout whilst the other is in operation. Forlow integrity systems with dual SISWcentrifugal fans the fans are “ductedmounted” with each fan installed in aseparate duct branch and a manifoldduct connection piece at the inlet toconnect to the extract ductwork.
For high integrity systems gas tightSISW fans shall be used and with dualfan arrangements the fans are “ductedmounted” with each fan installed in aseparate duct branch and a manifoldduct connection piece at the inlet toconnect to the extract ductwork.
Units are generally designed to belifted and positioned as one completeassembly so as to minimiseinstallation time.
The main features and components ofan Extract Fan Skid are presentedherein.
Standards
Wozair design and manufacturer itsFan Extract Skids to comply with ECdirectives, NF and AWE specifications.
Units comply with Directives and anyamending Directives:Machinery Directive 98/37/ECLow Voltage Directive 73/23/EECATEX Directive 94/9/ECEMC Directive 89/336/EEC
7.3 Extract Fan Skids
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7Section
Skid
The Extract Fan Skid is supplied as askid mounted assembly with the skidfabricated from hot rolled structuralsteel sections. The skid can bedesigned to BS 449 and withconsideration for transportation forcesand any seismic conditions. Skids arewelded by coded welders and hot dipgalvanized to EN 1461 aftermanufacture. If required main weldscan be subject to NDT. Lifting lugsand earthing points are provided.
Casing (Low IntegritySystems)
A crated unit is provided when usingDIDW centrifugal fans. The casingconsists of a rigid constructionframework with lagged infill panels forthermal insulation and noiseattenuation.
The frame work is continuouslywelded and manufactured fromstainless steel grade 1.4404 (316L) or1.4307 (304L). The frame work is 1.5mm, 2.0 mm or 3.0 mm dependantupon the size and application. Ifrequired the frame work can beinsulated with a closed cellelastomeric material or mineral woolto eliminate a heat bridge.
Infill panels are double skinned andflush mounted. Infill can be 25 mm or50 mm thick and is used to providethermal insulation and noiseattenuation. Infill material can beextruded polystyrene rigid boardbonded to the panel skin or mineralwool. Panel skins are manufacturedfrom the same material as the framework with a range of sheet
thicknesses available from 0.9 mm to2.0 mm. Hinged access panels areprovided for inspection andmaintenance of equipment.
A baseplate manufactured from thesame material as the frame work issandwiched between the frame workand the skid and is insulated ifrequired.
Externally mounted units can beprovided with a pitched roof to shedrain.
Fans (High IntegritySystems)
Fans are typically of the high integritySISW centrifugal type to NF0152/2 withnon-stalling and non-overloadingcharacteristics. Fans are generallybelt driven although direct drive fanscan be provided for operation withvariable speed drives. The fan casingshall be gas tight to the requirementsof NF0152/2 manufactured from mildsteel (type B) or stainless steel (typeD). Impellers can be mild steelpainted or stainless steel asappropriate.
7.3 Extract Fan Skids
Fans are driven by LV motors. Wherebelt drive is employed, belts are ananti-static, vee design. The motor ismounted on a frame integral to the fanset. The fan is isolated from the AirHandling Unit by anti-vibration mountsand flexible connections.
If required Wozair can supply fanssuitable for operating within a zone 1or zone 2 hazardous area and as suchthe fans shall incorporate anti-sparkfeatures.
Fans can be provided with thefollowing accessories: speed sensor,bearing monitoring, extendedlubricators, automatic greaselubricators, drain plug, access door,inlet and discharge guards and beltguards.
With dual fan arrangements fans areinstalled in separate duct branchescomplete with shut-off damper toenable maintenance on one fan to becarried out whilst the other is inoperation. Dual fans can beconfigured side-by-side or one abovethe other subject to practicaltransportation limits.
Inlet guide vane, manual or automaticisolation and non-return dampers canbe provided to control the airflow andisolate the fan.
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Motors
These are in accordance with NF0004/1, NF0004/2, NF0004/2, NF0032/1, BS4999 and BS 5000 suitable for directon line starting and operating on 415V.If required we can supply motor tooperate on any common 3 phase lowvoltage supplies of 50 Hz and 60 Hz.
If required Wozair can supply motorsrated suitable for use in a potentiallyhazardous area as required andcompliant with project specificationsand standards where stipulated.
Weather Louvres
Refer to section 7.3
Controls/Wiring
Refer to section 7.3
Safety Features
The units are provided with an ECDeclaration of Incorporation. Wherepersonnel can gain internal access tomaintain dampers or fan sets thenlights of the filament or fluorescenttype are provided operated from acommon switch. For the fan motor apush button emergency stop can befitted. As required any electricalcomponents shall be suitable for usein a hazardous area.
Ancillary Components
Refer to section 7.3
7.3 Extract Fan Skids
Testing
Various testing options are availableon the completed Extract Unit and gastight fans including:
For low integrity cased fans in a cratedunit:• Volume/pressure testing based on
BS 6583• Case deflection and leakage based
on EN 1886• Case leakage testing up to 3000 Pa• Indicative noise breakout testing• Measurement of the fan running
speed• Recording motor running current
For high integrity gas tight fans:• Pneumatic pressure test of fan
casing prior to painting orgalvanising
• Pneumatic pressure test of fancasing following assembly to twicethe working differential pressure
• Static and dynamic balancing ofimpeller
• Vibration measurements to therequirements of BS 6581 gradeG6.3
• Mechanical run test• Performance test to BS 848 Part 1• Measurement of the fan running
speed• Recording motor running current/
power input
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7Section
Mobile FiltrationUnits
Introduction
Wozair manufactures a range ofMobile Filtration Units to complimenttheir radial and axial safe changeHEPA filter systems.These units offer flexible solutions toextract ventilation problems wherespace is a premium and building/decommissioning and sitecircumstantial parameters precludethe use of conventional fixed filterbanks.
Legislation
Wozair Mobile Filtration Units shallbe fully compliant with EC Legislationand shall be supplied with EMCtesting certification.
Client Specifications
Wozair Mobile Filtration Units shallbe fully compliant with therequirements of NF or AWEspecifications and tailored to suitspecific site applications.
Technical SpecificationMaterials
Wozair Mobile Filtration Units shallbe available in Epoxy coated carbonsteel or Stainless Steel grades1.4307(304L) or 1.4404(316L).
Unit Specification
Wozair Mobile Filtration Units shallbe tailored to suit a range of clientspecific requirements and shallinclude as required:
• Rigid mounting frame with brakedcastors for mobility
• Lifting Lugs
• Pre-Filters with safe change facility
• Spark arrestors with safe changefacility
7.4 Mobile Filtration Units
• Primary HEPA Filters with safechange facility
• Secondary HEPA Filters with safechange facility
• Isolation Dampers for inlet andoutlet
• Depression Relief systems
• Pressure and Flow monitoringsystems
• DOP testing and sampling points
• Quick mix injector
• Pre-Heater
• Fans: Two stage contra rotatingaxial or Centrifugal types to suitclient requirements
• Local Control Panels to suit clientequirements and shall include asrequired:Local/Remote audible and visualalarmsEmergency Stop ButtonProgrammable Logic ControlThyristor ControlInvertor Speed ControlThermal/Thermistor cutouts
Testing
Wozair Mobile Filtration Units shallbe fully factory function tested forperformance and leakage.Witness and stage inspection pointsto client requirements.
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The QUICKMIX Injector is abreakthrough for plant designersproviding a simple low cost method ofinjecting and thoroughly mixing activeaerosol upstream of the HEPA filter.
Duct lengths can be reduced tobetween 2 – 6 duct diametersdepending on the system parameters.
The QUICKMIX Injector allows fora sampling to be conducted using asingle sampling probe providingnegligible pressure drop to theinstalled system.
The QUICKMIX Injector systemonly requires a conventional DOPgenerator and a compressed airsupply to ensure satisfactoryoperation.
7.5 Quick Mix Injectors
The Product
The QUICKMIX Injector ismanufactured from stainless steelgrades 1.4307 (304L) & 1.4404 (316L)and is mounted to the duct using aBS4504 PN6 Flange such that theinjector nozzle sits on the centre line ofthe duct system to ensure a uniformdistribution of the aerosol mix.
The QUICKMIX Injector requires acompressed air supply of 12-15 CFM@ variable pressures of 2-8 barThe standard unit is supplied withHansen quick release couplings.However a range of isolation valveoptions are available on request.
Quick Mix Injectors
Introduction
Wozair own the patent rights for theQUICKMIX Injector , a product thatwas designed, developed and testedby the Atomic Energy Authority toprovide a solution to challenge HEPAfilter systems where space constraintsrestrict ductwork systems to tightconfigurations precluding the use ofconventional methods of DOP testing.
Operation
The QUICKMIX Injector has beendeveloped to confirm the efficiency andeffectiveness of HEPA filtrationsystems within Nuclear plants,meeting the standards demanded bythe Nuclear Industry and it’sregulators, ensuring the safety andenvironmental acceptability of itsoperations.
The conventional way to generate awell mixed aerosol mist is to use longstraight lengths of ducting to allow‘natural’ mixing (creating expensiveand bulky process plants) or tointroduce mixing baffles into the ductsystem.
The inherent pressure drop introducedby methods such as this necessitatesthe use of larger fans which in turnmeans increased capital and plantrunning costs.
