System functional diagram

 

Air inlets

  • Shutters, silencers

 

Mixing chambers

  • Mixing operation of air exhausted from rooms with fresh air
  • Air parameters after mixing (e.g. enthalpy, relative humidity) are average and weighted parameters of mixed streams where “weights” are their mass streams

 

Coarse filters

  • Replaced approx. every 3 months
  • Coarse and fine dust filters
  • Moved out (access from side)
  • Mostly G3 to F5 Class
  • Initial resistances of flow from 30 to 50 Pa (air speed 3 m/s)
  • Admissible resistance (due to strength reasons) from 200 to 300 Pa

 

Surface coolers

  • E.g. coils of copper pipes, with copper fins, in a steel galvanized housing with condensed water vapour outlet
  • Cooled with iced water of a temperature of from 6oC to 12oC; with two tasks:
    • air cooling without moisture condensation (when the coil surface temperature is higher than the dew point temperature)
    • drying - air cooling with moisture condensation (when the coil surface temperature is lower than the dew point temperature)
  • Cleaning easiness

 

Fans

  • E.g. centrifugal with air blades, with adjusted multi-belt “V” transmission (the fan drive and the motor with regulated rotational speed)
  • Access through a hinged door
  • Air is heated up due to work done by the fan

 

Fine filters

  • Replacement after approx. 5  months (if a coarse filter is used)
  • Most often fine filters (e.g. F6 to F9), e.g. bag filters
  • Side or front access
  • Initial resistance of flow from 50 to 150 Pa (air speed 3 m/s)
  • Admissible resistance (due to strength reasons) from 300 to 400 Pa

 

Air flowmeters

  • A sensor in the air draught duct emits air flow speed signal (for the fan drive needs control)

 

Humidifiers

  • Steam humidifier - direct supply into an air duct of saturated vapour at a temperature from 105oC to 110oC under vapour overpressure of 1 bar (low pressure)
  • Water humidifier - through a direct air contact with sprayed water (nozzle humidifiers) or with water through a large surface bed (humidifiers with filling)
  • Materials: stainless steel
  • Used with a main filter requires supply with treated water or clean vapour

 

Heaters

  • Mostly surface heaters (copper coils, fin radiators)
  • Heating media: hot water, water vapour, electric energy
  • Important possibility of access for cleaning

 

Final filters

  • Replacement after approx. from 1 to 3 years (if coarse and fine filters are used)
  • Absolute filters (HEPA and ULPA), e.g. H10 to H17
  • Mounted in housings faced with false ceiling or in diffusers (rotational diffusers, rectangular shutters)
  • A possibility to equip with individual drive systems with fans securing air constant flow
  • Initial resistance of flow from 200 to 250 Pa (air speed from 0,45 do 1,5 m/s)
  • Admissible resistances (due to strength reasons) from 500 to 750 Pa.
  • Very important - filter sealing with housing (clamping frames, sealing with liquid gel)
  • Important - a possibility of pressure drop measurement in the filter from room

 

Duct draughts

  • Made of galvanized sheet or stainless steel
  • Access door - necessary for inspections, maintenance, cleaning
  • Tight duct section connections (loss problem)
  • Cleaning before shipment, final protection during assembly
  • Cleanness inspection before filters installation

 

Returning air fan

  • A centrifugal fan with a belt drive
  • Rotational speed control is not required
  • It is an exhaust fan in the fully fresh air systems

 

Returning air exhaust grills

  • In wall lower parts
  • Grill connection with wall - faced without protrusions
  • Possible exhaust equipment under floor

 

Other equipment

  • Vibration dampening and noise silencing equipment in ventilating ducts
  • Dampers, flaps in ventilating ducts
  • Silenced roof outlet of returning air (part)
  • Cooling water system (systems of constant flow speed): pumps,  cooling and returning water temperature meters, three-way valves for flow control through coolers, refrigerating units, fan coolers)
  • A heating water system - similar (with a heat exchanger “water vapour - heating water”)
  • A clean steam generator to humidifiers
  • Sensors and measuring paths of air flow speed, temperature, pressures, relative humidity
  • A computerized system: monitoring, alarming, control
  • Local control systems of laminar supply
  • Others