This dialog box is displayed when you select Chart Settings... in the Psychrometric Chart menu. It allows you to set the range and conditions for the generation of the psychrometric chart.

Psychrometric Chart Settings Dialog.

Barometric Pressure (kPa)

The overall atmospheric or barometric pressure affects values within the psychrometric chart. The default is 101.365 kPa, however you can set this manually to reflect conditions at your site. If you are unsure as to what value to enter here, it s recommended that you leave it at the default value.

Temperature

Maximum Temperature

This value sets the upper dry-bulb temperature limit of the plotted psychrometric chart. It can vary between the current minimum setting and 100C. It basically changes the right-most X axis value.

Minimum Temperature

This value sets the lower dry-bulb temperature limit of the plotted psychrometric chart. It can vary between the current maximum setting and -100C. It basically changes the left-most X axis value.

Snap

This setting controls the incremental temperature displayed when you click and drag the left mouse button within the chart. Temperature values will change only in increments of this value.

Absolute Humidity

Maximum Humidity

This value sets the upper absolute humidity limit of the plotted psychrometric chart. It can vary between the current minimum setting and 100 kPa. It basically changes the upper-most Y axis value.

Minimum Humidity

This value sets the lower absolute humidity limit of the plotted psychrometric chart. It can vary between the current maximum setting and 0 kPa. It basically changes the bottom-most Y axis value.

Snap

This setting controls the incremental absolute humidity displayed when you click and drag the left mouse button within the chart. Absolute humidity values will change only in increments of this value.

Default Position

Vertical Axis Units

Determines the units in which the Y-Axis value is given immediately below. It can be given as the absolute amount of moisture in g/kg, an amount relative to the saturation point at the current temperature, entered as a percentage, or as a vapour pressure which is linearly related to absolute humidity.

Dry-Bulb Temperature

Specifies the temperature of the current condition. In some applications, a default position cursor indicating this condition is displayed within the chart.

Vertical Axis Value

Specifies the humidity or vapour pressure of the current condition. This value must be given in the Vertical Axis Units selected above.