HVAC Systems • Ventilation
Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.
Air - Density and Specific Volume vs. Altitude
Density and specific volume of air varies with elevation above sea level.
Air Change Rate
Calculate air change rates - equations in imperial and SI units.
Air Change Rates in typical Rooms and Buildings
Fresh air (make up air) rquirements - or recommended air change rates (ACH) for typical rooms and buildings like auditoriums, kitchens, churches and more.
Air Curtains or Air Screens
Calculate air curtains or air screens in open doorways used to keep acceptable indoor comfort in buildings.
Air Duct Calculator
Online calculator to compute friction loss in air ducts.
Air Duct Components - Minor Dynamic Loss Coefficients
Minor loss (pressure or head loss) coefficients for air duct components.
Air Duct Velocities
Typical air duct velocities in applications like ventilation systems or compressed air systems.
Air Ducts - Friction Loss Diagram
A major friction loss diagram for air ducts - Imperial units ranging 10 - 100 000 cfm.
Air Ducts - Friction Loss Diagram
A major friction loss diagram for air ducts - in imperial units ranging 10 000 - 400 000 cfm.
Air Ducts - Friction Loss Diagram
A major friction loss diagram for air ducts - SI units.
Air Ducts - Major Friction Head Loss, Online Calculator
Head loss or major loss in air ducts - equations and online calculator for rectangular and circular ducts - Imperial and SI units.
Air Ducts - Major Friction Loss vs. Temperature and Pressure
The influence of temperature and air pressure on major friction loss.
Air Ducts - Minor Loss Coefficient Diagrams
Minor loss coefficient diagrams for air ductwork, bends, expansions, inlets and outlets - SI units.
Air Ducts - Sizing
Required duct area vs. air flow.
Air Ducts - Velocity Diagram
Air flow volume, duct size, velocity and dynamic pressure.
Air Filters - Arrestance and Efficiency
Air filters efficiency and arrestance.
Air Heating Systems
Air heating buildings - heat supply vs. air flow and temperature.
Air Intakes and Outlets
Ventilation systems - air intakes and outlets - rules of thumbs.
ASHRAE - American Society of Heating, Refrigerating and Air-Conditioning Engineers
Belt driven Fans - Fan vs. Motor Speed
Fan vs. motor speed in belt driven fans.
Belt Transmissions - Speed and Length of Belts
Calculate length and speed of belt and belt gearing.
Carbon Dioxide Concentration in Rooms Occupied with People
Carbon dioxide concentration in a room may indicate air quality and ventilation system efficiency.
Carbon Monoxide and Health Effects
Exposure to Carbon Monoxide - CO and health effects.
Circular Ducts - Dimensions
Standard size of circular ventilation air ducts.
Classification of Ventilation Systems
Ventilation systems can be classified by functions, distribution strategies or by ventilation principles.
Clean Rooms - Federal Standard 209
Clean rooms virtually free of contaminants like dust or bacteria.
Clean Rooms - ISO Standard 14644
Clean room class limits according ISO Standard 14644-1.
Friction loss coefficients in pipes, tubes and ducts.
Comfort Environments - Selecting Ventilation System
A quick selection guide of ventilation system in comfort environments.
Design of Ventilation Systems
Design procedure for ventilation systems - air flow rates, heat and cooling loads, air shifts according occupants, air supply principles.
Duct Sizing - the Equal Friction Method
The equal friction method for sizing air ducts is easy and straightforward to use.
Duct Systems - Pressure Classifications
Duct systems are commonly divided into three pressure classifications.
Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator.
Ducts - Cross-Sectional Area vs. Diameter
Circular ducts sross-sectional areas.
Ducts - Sheet Metal Gauges
Thickness of sheet metal used in ductwork.
Ducts Sizing - the Velocity Reduction Method
The velocity reduction method can be used when sizing air ducts.
Ductwork - Seal Classes
Ductwork air leakage classes.
Ductwork - Supports
Recommended distance between ductwork support hangers.
Energy Equation - Pressure Loss vs. Head Loss
Calculate pressure loss - or head loss - in ducts, pipes or tubes.
Equivalent Diameter - Rectangular vs. Circular HVAC Ducts
Rectangular equivalent diameter for air flows between 100 - 50000 cfm.
Evacuation of Air - minimum Capture Velocities to avoid Pollution products transferred to the Room
Capture velocities to avoid pollution products from galvanic baths, spray painting boxes and more contaminating the surrounding room and environment.
Sizing of exhaust hoods - air volume flow and capture velocities - online exhaust hood calculator.
Exhaust Outlets - Capturing Air Velocities
Capturing air velocity in front of an exhaust outlet - online exhaust outlet velocity calculator.
Fan Affinity Laws
The affinity laws can be used to calculate resulting volume capacity, head or power consumption when speed or wheel diameters are changed.
Fan AMCA Classification
Fan classification established by AMCA.
Fan Capacity Diagrams
Pressure, head, air flow volume and fan capacity diagrams.
Fan Inlets - Air Density vs. Suction Pressure
High suction pressure at a fan inlet decreases the density of air - and should be corrected for proper selection of the fan.
Fan Motors - Starting Torques
The motor must be capable of accelerating the fan wheel to it's operating speed.
Fans - Calculate Air and Brake Horsepower
AHP - Air Horse Power and BHP - Brake Horse Power.
Fans - Capacity Control
How to modulate fans and their capacities.
Fans - Efficiency and Power Consumption
Power consumption and typical efficiencies of fans
Fans - Troubleshooting
Guide to troubleshooting fan problems.
Fans - Volume Flow, Pressure Head and Power Consumption vs. Air Temperature and Density
The temperature and density of the air influences on the volume flow, pressure head and power consumption in a fan.
Fluid Flow - Equivalent Diameter
Convert rectangular and oval duct geometry to a equivalent circular diameter - online calculator with imperial and SI-units.
Fluid Flow - Hydraulic Diameter
Calculate hydraulic diameter for pipes and ducts.
Free Area Ventilation
Ventilation required for attic areas.
Exhaust ventilation from garages and workshops.
Gas Vent Termination - Clearance vs. Roof Slope
Clearance tolerance for gas vent terminations vs. roof slope.
Ventilation and heat-recovery calculations, sensible and latent heat - online calculators - imperial units.
Heat Recovery Efficiency
Classification of heat recovery efficiencies - temperature efficiency, moisture efficiency and enthalpy efficiency - online heat exchanger efficiency calculator.
Heaters and Coolers in Ventilation Systems
Basic equations for heat transfer - selecting criteria for heaters and coolers in ventilations systems.
Sprayed coils, spinning discs and steam humidifiers.
HVAC Dampers - Pressure Loss
Pressure head loss in HVAC dampers.
HVAC Diagram - Online Drawing Tool
Draw HVAC diagrams online with this Google Drive drawing tool.
HVAC Ducts - Air Velocities
Recommended air velocities in HVAC ducts.
Indoor Design Temperatures
Recommended indoor temperatures in summer or winter.
Industrial Environments - Selecting Ventilation System
A quick selection guide for ventilation systems/principles in industrial environments.
Industrial Product and Production Processes - Climate Conditions
Recommended indoor temperature and humidity for common industrial products and production processes.
Mechanical Energy Equation vs. Bernoulli Equation
The Mechanical Energy Equation compared to the Extended Bernoulli Equation.
Natural Draft - Air Flow Volume and Velocity
Air flow - volume and velocity - due to stack or flue effect caused by indoor hot and outdoor cold temperature difference.
Odor from Persons - Required Ventilation
Required air ventilation to handle odor and smell from persons.
Odor Intensity from Persons
Odor intensity from persons vs. room volume and ventilation.
Outdoor Makeup Air
Acceptable indoor air quality and required make up air.
Outdoor Supply Air Rates
Recommended supply air rates of outdoor air - with or without smoking - in rooms like banks, assembly halls, hotels and many more.
Pollution Concentration in Rooms
Concentration of a pollution in a limited space as a room depends on the amount of polluted material spread in the room, supply of fresh air, outlets positions and construction, principles used for supply and outlet from the space.
Pumps vs. Compressors, Blowers and Fans
The difference between pumps, compressors, blowers and fans.
Rectangular Air Ducts - Velocity Diagram
Velocity diagram for rectangular air ducts - metric units.
Rectangular Ducts - Dimensions
Commonly used metric dimensions for rectangular air ducts in ventilation systems.
Rectangular Ducts - Hydraulic Diameter
Calculate hydraulic diameter for rectangular ducts - metric units.
Relative Humidity in Production and Process Environments
Recommended relative humidity in production and process environments - like libraries, breweries, storages and more.
Required Air Flow to Remove Moisture
Air flow required to remove vapor production from a room.
Required Space per Person
Room area per person - may be used to calculate typical indoor climate loads.
Roughness & Surface Coefficients
Surface coefficients that can be used to calculate friction and major pressure loss for fluid flow with surfaces like concrete, galvanized steel, corroded steel and more.
In a wet scrubber process air is drawn through a mist of water made by spray nozzles, then through separators where water droplets with dust and particles are removed.
Sizing Circular Ducts
A rough guide to maximum air volume capacity of circular ducts in comfort, industrial and high speed ventilation systems.
Spiral Duct Elbows - Weights
Ductwork - weight of galvanized round spiral elbows.
Spiral Ducts - Dimensions
Standard dimensions of spiral ducts - Imperial units.
Stack or Flue Effect
The stack or flue effect occurs when the outdoor temperature is lower than indoor temperature.
STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure
The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.
Types of Fans
Axial and propeller fans, centrifugal (radial) fans, mixed flow fans and cross flow fans.
Types of Fans - Capacity Ranges
Centrifugal, axial and propeller fans and their capacity ranges.
U-Tube Differential Pressure Manometers
Inclined and vertical u-tube manometers used to measure differential pressure in flow meters like pitot tubes, orifices and nozzles.
Velocity Classification of Ventilation Ducts
Recommended air velocities in ventilation ducts
Ventilation and Air Conditioning Equipment - Area Required
Required size of ventilation and air conditioning rooms according DIN 1946.
Ventilation Components - Minor Pressure Loss
Pressure loss in ventilation system components like dampers, filters, heaters, coolers and more.
Ventilation Dampers - Classification
Dampers in ventilation systems may be classified through function, construction or leakage class.
Ventilation Ducts - Minor Loss Resistance
Minor pressure or head loss in ventilation ducts vs. air velocity - minor loss coefficient diagram.
The efficiency of a ventilation system may be related to temperature and/or pollution concentrations.
Classification of air filters used in ventilation systems.
Some commonly used ventilation principles - short cut, mixed air, displacement and piston principle.
Ventilation Systems - Return Intakes
Size and capacities of air return intakes.