HVAC Input Presentation by Team ABS Air Tech Gurgaon

HVAC Systems Understanding the basis

Table of Contents

Introduction to HVAC SystemsHVAC System TypesHVAC Piping SystemHVAC Air Distribution EquipmentsFans and PumpsHVAC Instrumentation and ControlHVAC System Commissioning

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Introduction to HVAC SystemsThis article introduces the heating, ventilating and air-conditioning (HVAC) systems. The primary function of HVAC systems is to provide healthy and comfortable interior conditions for occupants; well-designed, efficient systems do this with minimal non-renewable energy and air, and water pollutant emissions.



Introduction to HVAC SystemsThe purpose of HVAC design is both high indoor air quality and energy efficiency. These dual considerations require an integrated design approach. Rigs heating, ventilation, and air conditioning system (HVAC) creates a climate that allows for maximum comfort by compensating for changing climatic conditions.

Though more costly to install and more complicated to operate, a chiller plant offers a number of benefits over a large number of individual packaged cooling units, including greater energy efficiency, better controllability, cheaper overall maintenance, and longer life. Using a comprehensive approach to building design, designers around the world have succeeded at creating highly efficient air-conditioning systems that provide excellent comfort at significant savings.



Introduction to HVAC SystemsHeating, ventilating and air- conditioning (HVAC) systems reduce the environmental impact of rigs/buildings in several key ways. The most important function of a HVAC systems is to provide the rig/buildings occupants with healthy and comfortable interior conditions. A carefully designed, efficient system can do this with minimal non- renewable energy and air and water pollutant emissions to minimize the environmental impact. Cooling equipment that avoids chlorofluorocarbons and hydro- chlorofluorocarbons (CFCs and HCFCs) eliminates a major cause of damage to the ozone layer.*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Introduction to HVAC SystemsEven the best HVAC equipment and systems cannot compensate for a faulty rig design. Problems of this type cause inherently high cooling and heating needs and consume unnecessary resources and should be corrected if possible. Conservation of non-renewable energy through an intelligent architectural design offers the greatest opportunity for savings. The most important factors in these designs are careful control of solar gain, while taking advantage of passive heating, day lighting, natural ventilation and cooling. The critical factors in mechanical systems' energy consumption - and capital cost - are reducing the cooling and heating loads they must handle. *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


HVAC System TypesTypes of System Designs - There are several major heating, ventilating, and air conditioning system types in wide spread use today. These are air systems, hedonic and steam systems, and unitary type systems. Most systems in use today fall into one of these categories, or are a combination or variation of them. Each type of system has advantages and disadvantages.

Air cooled- Air cooled Chillers *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Cooled Chiller AdvantagesLower installed costQuicker availabilityNo cooling tower or condenser pump requiredLess maintenanceNo mechanical room required



Water Cooled - Sea Water cooled Chillers - Fresh Water cooled Chillers



Water-Cooled Chiller advantages

Higher efficiencyCustom selection in larger sizesLarge tonnage capabilitiesIndoor Chiller locationLonger life



Purpose of an air handling system Air Handling Systems *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Objectives

In the following slides, we will study the components of air handling systems in order to: Become familiar with the components

Know their functions

Become aware of possible problems*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Main subsystems*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Exhaust Air GrilleHeaterSecondary FilterRe-circulated air*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Weather louver

Silencer

Flow rate controller Control damper

To prevent insects, leaves, dirt and rain from entering

To reduce noise caused by air circulationAutomated adjustment of volume of air (night and day, pressure control)Fixed adjustment of volume of air

Components (1)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Heating unit Cooling unit /dehumidifier

Humidifier

Filters

DuctsTo heat the air to the proper temperature

To cool the air to the required temperature or to remove moisture from the air

To bring the air to the proper humidity, if too low

To eliminate particles of pre-determined dimensions and/or micro-organisms

To transport the airComponents (2)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Filter classesDust filtersStandardAerosolFineCoarseULPAHEPA10 m > Dp > 1 mDp > 10 mDp < 1 mF5 - F9G1 - G4U 14- 17H 11 - 13EN 1822 StandardEN 779 Standard*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Primary panel filterSecondary filterHEPA or tertiaary filter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct heaters Room Heters

Silensers *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Volume control damperDe-humidificationFilter Pressure GaugesAHU with fan Variable Speed Controller Dry airFire Dampers*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Annex 1, 17.26Regulation of room pressure pressure differentials conceptRoom pressure gaugesRoom pressure indication panel*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Pressure cascade injectables Protection from micro-organisms and particles*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Pressure cascade solidsProtection from cross-contamination*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan Coil Unit*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Self Contain Unit *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


HVAC Air Distribution Equipments

Diffusers

4 Way Diffusers Two Way Diffusers One Way Diffuser

Round Diffusers*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Cabin Units



Return / Exhaust Grilles*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


ContentsFan DesignFan PerformanceFan-duct SystemsDuct ConstructionAir Duct DesignFans and Pumps *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan DesignCommon types of fansCentrifugal fans: radial, forward curved, air foil (backward curved), backward inclined, tubular, roof ventilatorAxial fans: propeller, tube-axial, vane-axialFan arrangementsMotor location, air discharge orientation, drive train type (direct drive or pulley drive)Centrifugal: single width single inlet (SWSI), double width double inlet (DWDI)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Centrifugal and axial fan componentsAXIAL FANSCENTRIFUGAL FANS*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


PropellerTube-axialTube-vaneAXIAL FANS*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Tubular centrifugal fanCentrifugal roof ventilatorCENTRIFUGAL FANS(* Note the airflow paths and impeller design.)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Drive arrangements and motor positions*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Single- and double-width centrifugal fans*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan PerformanceMajor parametersFan volume flow rate (m3/s or l/s), VfFan total pressure ptf, fan velocity pressure pvf & fan static pressure psf (Pa)Fan power & efficiencyFan power or air power (W) = ptf x VfFan power input on the fan shaft (brake horsepower), PfFan total efficiency: t = ptf x Vf / PfCombined aerodynamic, volumetric & mechanical efficienciesFan static efficiency: s = psf x Vf / PfAir temp. increase through fan, Tf = ptf /(cpat)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan performance curvesTotal pressureStatic pressureFan total efficiencyFan static efficiencyFan power inputVelocity pressureVolume flow rate*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Typical fan performance curve*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan PerformanceFan LawsSpeed (n)Volume flow (V)Total pressure loss (p )Air density ()For air systems that are geometrically & dynamically similar: (D = impeller diameter)c.f.: pump laws*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Velocity triangle at the blade inlet and outlet of a centrifugal fanCENTRIFUGAL FANS*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan PerformanceMajor issues causing energy losses to a centrifugal fan:Circulatory flow between the bladesAir leakage at the inletFriction between fluid particles and the bladeEnergy loss at the entrancePartially filled passage*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Operating characteristics for a backward-curved centrifugal fan*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Total efficiency curves for centrifugal fans*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan power curves for centrifugal fans with same impeller diameter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan pressure curves for centrifugal fans with same impeller diameter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Velocity triangles for a vane-axial fanAXIAL FANS*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan pressure curves for axial fans with same impeller diameter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan efficiency curves for axial fans with same impeller diameter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan power curves for axial fans with same impeller diameter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Performance curves for controllable-pitch vane-axial fans*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsDuct pressure changes (c.f. atm pressure)Static pressure (SP)Velocity pressure (VP) = V2 / 2 gTotal pressure (TP) = SP + VPFan: a pumping deviceFan (total) pressure = pressure difference between fan inlet and fan dischargeAt fan suction/inlet, SP = negative (c.f. atmospheric); at discharge, SP = positive*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsPressure characteristicsSP and VP are mutually convertible (or)TP always decreases in the direction of airflowFor constant-area straight duct sectionsVelocity and VP are constantTP change = SP changeWhen duct cross-sectional areas are reducedVelocity and VP increaseAbsolute value of both TP and SP decreaseDynamic losses from elbow, dampers, etc.*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsFan-duct systemsFlow resistance R, pressure drop p and volume flow rate V

Duct sections in series:Duct sections in parallel:o*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsFan-duct systemsTerminologyPrimary air (conditioned air or makeup air)Secondary air (induced space air, plenum air, or recirculating air)Transfer air (indoor air that moves from an adjacent area)System curve: volume flow vs pressure lossSystem operating point*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsSystem effect ptsIts additional total pressure loss caused by uneven or non-uniform velocity profile at the fan inlet, or at duct fittings after fan outletDue to the actual inlet and outlet connections as compared with the total pressure loss of the fan test unit during laboratory ratingsInletOutlet*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan system operating point & system effect*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsModulation of air systemsConstant volume systemVolume flow rate remains constantSupply temperature is raised during part loadVariable-air-volume (VAV) systemVolume flow rate is reduced to match part load operationModulation curve*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan modulation curve*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsFan modulation methodsDamper (vary the opening of the air flow passage)Waste energyInlet vanes (opening & angle of inlet vanes)Low cost; less efficient than following typesInlet cone (peripheral area of fan impeller)Inexpensive; for backward curved centrifugal fanBlade pitch (blade angle of axial fan)Fan speed (using adjustable frequency drives)Most energy-efficient; but usually cost more*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Damper, inlet vanes & fan speed modulation*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Inlet vane modulation*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan speed modulation using AC inverter*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsFan surge (in centrifugal fan)Occurs when air volume flow is not sufficient to sustain the static pressure difference between discharge & suctionDischarge pressure is reduced momentarilyVolume flow & pressure fluctuationsCreate noise & vibrationSurge region: shall avoid operation in itFan stall (in axial fans)When smooth air flow suddenly breaks & pressure difference across the blades decreasesThe fan loses pressure capability drastically*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Stall and stall region of an axial fan*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Fan-duct SystemsFan selectionSelect fan type + determine fan sizeImportant factors:Pressure-volume flow operating characteristicsFan capacity modulationFan efficiencySound power levelAirflow directionInitial cost*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionTypes of air ductSupply air ductReturn air ductOutdoor air ductExhaust airDuct sectionsHeader or main duct (trunk)Branch duct or runout



Duct ConstructionDuct systemsMax. pressure difference (between air inside the duct and the ambient air)125, 250, 500, 750, 1000, 1500, 2500 PaCommercial buildingsLow-pressure duct system: 500 Pa, max 12 m/sMedium-pressure system: 500-1500 Pa, max 17.5 m/sResidential buildings: 125 Pa or 250 PaIndustrial duct system: P can be higher*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionDuct material: e.g. UL (Underwriters Laboratory) standardClass 0: zero flame spread, zero smoke developedIron, galvanized steel, aluminum, concrete, masonry, clay tileClass 1: flame spread 25, smoke developed 50Fiberglass, many flexible ductsClass 2: flame spread 50, smoke developed 100*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionShapes of air ductRectangularMore easily fabricated on site, air leakageRoundLess fluid resistance, better rigidity/strengthFlat ovalFlexibleMultiple-ply polyester film w/ metal wire or stripsSMACNA (Sheet Metal and Air Conditioning Contractors National Association) standards*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Rectangular ductRound duct w/ spiral seamFlat oval ductFlexible duct(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Transverse joint reinforcement(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionDuct specificationSheet gauge and thickness of duct materialTraverse joints & longitudinal seam reinforcementsDuct hangers & their spacingTapes & adhesive closuresFire spread and smoke developedSite-fabricated or factory-/pre-fabricated*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionDuct heat gain or lossTemperature rise or dropDuct insulation (mounted or inner-lined)Reduce heat gain/loss, prevent condensation, sound attentuationMinimum & recommended thicknessSee ASHRAE standard or local codesTemperature rise curvesDepends on air velocity, duct dimensions & insulation*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Temperature rise from duct heat gain(Source: Wang, S. K., 2001. Handbook of Air Conditioning and Refrigeration)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionFrictional lossesDarcey-Weisbach EquationHf = friction head loss, or pf = pressure loss

f = friction factor (dimensionless)L = length of duct or pipe (m)D = diameter of duct or pipe (m)v = mean air velocity in duct (m/s)*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Mode of airflow when air passes over and aroundsurface protuberances of the duct wall >

Duct ConstructionDuct friction chartColebrook formula

Roughness & temperature correctionspf = Ksr KT Kelpf,cKsr = correction factor for surface roughnessKT = correction factor for air temperatureKel = correction factor for elevation*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Friction chart for round duct*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionCircular equivalentHydraulic diameter, Dh = 4 A / PA = area (mm2); P = perimeter (mm)Rectangular duct:

Flat oval duct:*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionDynamic lossesResult from flow disturbances caused by duct-mounted equipment and fittingsChange airflow paths direction and/or areaFlow separation & eddies/disturbancesIn dynamic similarity (same Reynolds number & geometrically similar duct fittings), dynamic loss is proportional to their velocity pressure*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionLocal or dynamic loss coefficientRatio of total pressure loss to velocity pressure*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionDuct fittingsElbowsConverging or diverging tees and wyesEntrances and exitsEnlargements and contractionsMeans to reduce dynamic lossesTurning angle, splitter vanesASHRAE duct fitting databaseFitting loss coefficients*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Region of eddies andturbulences in a round elbow5-piece 90o round elbow*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Rectangular elbow, smooth radius, 2 splitter vanesMitered elbow and its secondary flow*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Airflow through arectangular convergingor diverging wye*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


EntranceExit*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Abrupt enlargementSudden contraction*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct ConstructionFlow resistance, RTotal pressure loss pt at a specific volume flow rate V

Flow resistance in series:

Flow resistance in parallel:



Total pressure loss and flow resistance of a round duct section*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Flow resistance in seriesFlow resistance in parallel*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Flow resistance for a Y connection*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignOptimal air duct designOptimal duct system layout, space availableSatisfactory system balanceAcceptable sound levelOptimum energy loss and initial costInstall only necessary balancing devices (dampers)Fire codes, duct construction & insulationRequire comprehensive analysis & care for different transport functions*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Flow characteristics of a supply duct system*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignDesign velocityConstraints: space available, beam depthTypical guidelines:Main ducts: air flow usually 15 m/s; air flow noise must be checkedWith more demanding noise criteria (e.g. hotels), max. air velocity: main duct 10-12.5 m/s, return main duct 8 m/s, branch ducts 6 m/sFace velocities for air-handling system components*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignReduce dynamic losses of the critical pathMaintain optimum air velocity through duct fittingsEmphasize reduction of dynamic losses nearer to the fan outlet or inlet (high air velocity)Proper use of splitter vanesSet 2 duct fittings as far apart as possibleAir duct leakageDuct leakage classificationAISI, SMACNA, ASHRAE standards *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignFire protectionDuct material selectionVertical ducts (using masonry, concrete or clay)When ducts pass through floors & wallsUse of fire dampersFilling the gaps between ducts & bldg structureDuct systems for industrial applicationsAny other fire precautions?*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignDesign procedure (computer-aided or manual)Verify local codes & material availabilityPreliminary duct layoutDivide into consecutive duct sectionsMinimise local loss coefficients of duct fittingsSelect duct sizing methodsCritical total pressure loss of tentative critical pathSize branch ducts & balance total pressure at junctionsAdjust supply flow rates according to duct heat gainResize duct sections, recalculate & balance parallel pathsCheck sound level & add necessary attenuation*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignDuct layoutSymmetric layout is easier to balanceSmaller main duct & shorter design pathFor VAV systems, duct looping allows feed from opposite directionOptimize transporting capacity (balance points often follow the suns position)Result in smaller main ductCompare alternative layouts & reduce fittingsFor exposed ducts, appearance & integration with the structure is important*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Typical supply duct system with symmetric layout & looping*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Air Duct DesignDuct linerLined internally on inner surface of duct wallMainly used for noise attenuation & insulationFiberglass blanket or boardsDuct cleaningPrevent accumulation of dirt & debrisAgitation device to loosen the dirt & debrisDuct vacuum to extract loosened debrisSealing of access openings*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


Duct breakout noise*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


HVAC Piping System*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


HVAC Instrumentation and Control*www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


HVAC System CommissioningThe key elements of commissioning include:

Installation checks. Check installed equipment to ensure that all associated components and accessories are in place. Operational checks. Verify and document that systems are performing as expected, and that all sensors and other system control devices are properly calibrated. Documentation. Confirm that all required documentation has been provided, such as a statement of the design intent and operating protocols for all building systems. O&M manuals and training. Prepare comprehensive operation and maintenance (O&M) manuals, and provide training for rig operations staff. Ongoing monitoring. Conduct periodic monitoring after the school is occupied to ensure that equipment and systems continue to perform according to design intent.

Correctly implemented, commissioning is extremely cost-effective, and should improve the delivery process, increase systems reliability, improve energy performance, ensure good indoor environmental quality, and improve operation and maintenance of the facility. *www.absairtech.in || www.abscleanroom.com || www.absventilation.com || www.abscoldroom.com


*You will recognize this picture from a previous slide, but we repeat it in order to emphasize the following:

An air handling system introduces pre-treated air, in order to provide a manufacturing environment with specified cleanliness, temperature and humidity in order to prevent product contamination and degradation. Air is then exhausted from the manufacturing environment. *Objectives:

For you, as inspectors, to be able to judge whether the air handling systems which you encounter during your factory inspections are adequate or not, it is necessary to know how such systems work, and to be aware of what problems may arise in terms of the components of the system.

Therefore, the objectives of this part of module 3 are to study the components of air handling systems in order to:

Become familiar with the components

Know their functions

Become aware of possible problems

*To understand the air handling systems, it is necessary to know what their components are.

A conventional Air Handling System has 4 sub-systems:

1. Air handling of the incoming (fresh) air: elimination of coarse contaminants and protection from frost if necessary. In the case of air re-circulation, the fresh air is also called make-up air.

2. Central air handling unit (AHU), where the air will be conditioned (heated, cooled, humidified or de-humidified and filtered), and where fresh air and re-circulated air, if any, (indicated here by the dotted line) will be mixed.

3. Air handling in the rooms under consideration (pressure differential system, additional filtration, air distribution).

4. Air exhaust system (filtration).

*Another way to look at an air handling system is to consider the different components and to know their function.

Some of the components, particularly the filters, are essential to ensure the quality of the air.

We will later consider individual components in detail.

Of course, a well-designed air handling system must not only be properly designed, but also properly installed, qualified and maintained (sealed ducts, tight filters).

(The trainer should make the audience aware that this slide is just an example, and that all components may not necessarily be present in each system.)*A typical HVAC unit consists of a small number of elements only.

It is important that these elements are compatible, properly installed, and fulfilling their goal.

Whereas a weather louvre and silencer are less critical elements, the components associated with the flow rate control are essential, as they allow adjustment of the air volumes supplied to the rooms, which in turn forms the base for a pressure differential concept: to have an automated or a fixed system is largely a financial matter, but a fixed system is more difficult to set up.

Silencer check internal lining material of silencer as this can cause contamination.

*Heating and cooling units (batteries), as well as humidifiers are used to adjust the climate in the room (temperature and humidity). Special de-humidifiers, on a dessiccant base, will be addressed later.

Filters are one of the main components, as they determine the size of airborne particles that pass through them, and thus the hygiene class.

It is wise to protect the finer filters by pre-filters, thus extending their life cycles, and making them less prone to clogging.

Ducts transport the air from the air handling units to and from the rooms. Inspectors must verify that ducts do not have internal insulation as this is a great source of contamination. *There are different air types to be considered within the air handling system:

Fresh air (if the plant is of the re-circulation type, it is necessary to replace some of the re-circulating air with fresh air, which is then called make-up air).

A proportion of about 15% fresh air is normal, but this proportion can vary, depending on factors such as number of people, National Regulatory Authority requirements, the presence of certain substances in the air, leakage due to pressure control, etc.

Supply air to the rooms

Exhaust air from the rooms

Return air (about 85% is being re-circulated)*The filtration efficacy depends on several mechanisms, and results in a rough filter classification.

The diagram shows the commonly used classification, with current abbreviations G = Gross, F= Fine, H= High, U= Ultra.

Filters are certified by the suppliers (challenge/efficiency test), but are often not properly installed or can be damaged. Leak tests (integrity tests), showing leakage of air through the filter itself or through its frame, therefore, have to be performed. Integrity tests are usually only carried out on the Aerosol filters (HEPA & ULPA).

Integrity or penetration testing is performed to detect leaks from the filter media, filter frame and seal. The challenge is a poly-dispersed aerosol usually composed of particles ranging in size from one to three microns. The test is done in place and the filter face is scanned with a photometer probe; the measured downstream leakage is taken as a percentage of the upstream challenge. Integrity tests should be carried out with filters installed in the system and should be carried out by an independent body (not the filter supplier).

The efficiency test, on the other hand, is used to determine the filter's rating. This test uses a mono-dispersed aerosol of 0.3 micron size particles, relates to filter media, and usually requires specialized equipment. Downstream readings represent an average over the entire filter surface. Therefore, leaks in a filter may not be detected by an efficiency test.*This slide shows Primary Panel filters, which are used mainly for lower filtration efficiency or as pre-filters Secondary filters, consisting of mini-pleated media or filter bags, and is used for higher filtration efficiency. HEPA or tertiary filters, usually being the final filter in the system, providing the highest filtration efficiency. Though there is a strong relationship between filter efficiency and cleanroom class, a filter of a high efficiency does not guarantee a high cleanroom class, as many other elements play a role, such asAir flow (how the air is extracted, how well the room is flushed)Air speed and number of air changesPositions of air terminalsLayout and presence of objectsPersonnel and clothingEquipment (not all machines are designed to operate in a clean environment!)Proper installation and proper maintenance*This slide shows additional elements of the air handling units.

For humidification purposes, especially in clean areas, high purity water should be used, to avoid contamination.

The silencer is not important from a GMP point of view, but from an environmental one, as ventilation units can be very noisy. Be sure that the silencers are manufactured of suitable materials as the linings of standard silencers can contaminate air with particulates.

Depending on the local legislation, the installation of silencers can be mandatory.

The cooling unit is important during the hot season. Be aware that stagnating water (condensed water) can bring bacterial growth, which can contaminate the filters, pass through them (depending on their retention properties) and end up contaminating production areas.

It is essential that there is no stagnating water. Cooling coils can be sanitized as well.

Do remember that, if filters are not properly maintained, micro-organisms may grow through the filters and be carried towards the production rooms.*Dampers to control pressure differentials are important. They can be automated or fixed. As filters get dirty the system pressure losses increase, and if airflow is not regulated, the flow decreases and pressure differentials change. This could cause flow reversal and cross-contamination. Variable speed drives for fan motors are also commonly used to control airflow.

In some cases, it is necessary to have very dry air for galenical reasons in certain rooms (production of effervescent tablets and humidity sensitive products in general).

To generate dry air, the air supplied to the production is passed over an adsorbant (silicagel, lithium chloride, etc.) where the humidity is removed from the air. The adsorbant is then re-generated, on a continuous or on a batch-wise base.*One of the main points in the design of production rooms is the pressure differentials concept.

Pressure differentials must be defined, monitored and alarmed in critical cases.

The overpressure of each room is measured against a reference point in the factory (point zero). As discussed earlier, the pressure regulation can be fixed or automated. Pressure control can be by means of automatic air flow control dampers (as shown in slide 15) or by means of fan speed control. Whatever the means used it is important to ask the manufacturer how they ensure that the pressure cascade is maintained as the filters get dirty.

In the following slides, we are going to see that an overpressure concept can be very different for sterile products and for solid products.*This slide illustrates the pressure differential system in a sterile area where the overpressure is kept high in the rooms, mainly in the A/B class room, to prevent the entry of micro-organisms.

(The level of overpressure is reflected by the absolute pressure in Pascals).To enter all rooms, it is necessary to go through airlocks.

In this particular example, the pressure differential in sterile areas is set up at 15 Pa between zones of different cleanliness, in accordance with FDA, EC and PIC/S regulations. Other values may apply in other regions.

It must be understood that high pressure differentials have an influence on the stability of building elements such as walls and doors. Factory layouts must be carefully planned, in order not to have too high a pressure differential between entrance and exit of a sterilising or depyrogenating tunnel, as the air flow may significantly affect the temperature in a tunnel.

Pressure differentials must be constantly monitored.The loss of overpressure in a filling room for injectables may mean the loss of the batches under production and the need for complete sanitation of the facility. It is therefore essential that the systems are designed in such a way that there is no loss of overpressure in case of power loss (overpressure fan should be linked to emergency power grid).*This slide illustrates the pressure differential system in a solids area where the overpressure is kept high in the corridors, to prevent cross-contamination.

In this case, we are not too worried by the microbial contamination, but rather by dust coming out of rooms where process work is being done, and thus contaminating other rooms.

The entry into some rooms (containing dangerous products such as hormones, cytotoxics, low RH products or strongly coloured products) is protected by airlocks.**********************************************

HVAC Input Presentation by Team ABS Air Tech Gurgaon

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