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Problems Loading HumiCalc
More About Modes
More About Known Values
More About Units
More About Calculated Values
Problems Loading HumiCalc
If you cannot load HumiCalc, first be sure that you are using a supported browser and operating system: Windows 95/98, NT, 2000, Millennium, XP or above, using only Internet Explorer 4.0 or above.
If it still doesn't work, you may need to adjust the Security Settings in Internet Explorer. Try the following:
- Select Tools in the header menu of your browser
- Select Internet Options
- Under the Security Tab, select Custom Level
- Under Download Unsigned ActiveX Controls, select Prompt
- Save the settings
- Restart your browser
- Download HumiCalc again; when asked whether to use ActiveX Controls, say YES
NOTE: You need to turn off any pop-up blockers.
Allow plenty of time for downloading; it may take at least two minutes, even with a high speed connection like cable or T1.
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More About Modes
HumiCalc may be operated in any of three modes: Normal, Two Temperature, or Two Pressure.
Normal Mode
NORMAL is the default mode of HumiCalc and will solve a majority of your humidity conversion problems. Normal mode converts any one humidity parameter to all other humidity parameters at a single test temperature and test pressure.
To select Normal mode, choose Normal from the MODE drop-down in the Configuration frame. The top parameter in the KNOWN VALUES frame (%RH) is the known humidity parameter. The other parameters are the temperature and pressure that the calculation is to be performed at.
Two Temperature Mode
The TWO TEMPERATURE mode is used primarily in conjunction with humidity generators that employ the fundamental principles of "Two Temperature" humidity generation. This mode is helpful in determining all humidity parameters at a given Test Temperature and Test Pressure when the Saturation Temperature and Saturation Pressure are known, or vice versa.
To place HumiCalc in the TWO TEMPERATURE mode, select Two Temperature from the MODE drop-down. The top parameter in the Known Values frame (initially Saturation Temperature) is the known humidity parameter. The next parameter, Saturation Pressure, is the absolute pressure at the point of saturation. The final two parameters, Test Temperature and Test Pressure, are the same as in other modes, and are the conditions at which the conversions take place.
The TWO TEMPERATURE mode always requires Saturation Pressure as one of its known inputs, while the TWO PRESSURE mode always requires Saturation Temperature as one of its known inputs. With this exception, Two Temperature and Two Pressure modes are identical.
Two Pressure Mode
The TWO PRESSURE mode is used primarily in conjunction with humidity generators that employ the fundamental principles of "Two Temperature" humidity generation. This mode is helpful in determining all humidity parameters at a given Test Temperature and Test Pressure when the Saturation Temperature and Saturation Pressure are known, or vice versa.
To place HumiCalc in the TWO PRESSURE mode, select Two Pressure from the MODE drop-down. The top parameter in the Known Values frame (initially Saturation Pressure) is the known humidity parameter. The next parameter, Saturation Temperature, is the temperature of the gas at the point of saturation. The final two parameters, Test Temperature and Test Pressure, are the same as in other modes, and are the conditions at which the conversions take place.
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More About Known Values
HumiCalc requires you to know at least one humidity-related parameter before it can calculate others. The top listed value in the Known Values frame is always this humidity-related parameter. To change the known parameter, click on the KNOW drop-down and select a new parameter from the List.
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More About Units
All values in HumiCalc may be expressed in a variety of units. The current units are displayed in the Units frame. Whenever units are changed, all affected values update immediately.
Temperature Units
The current temperature units are indicated in the Units frame in the drop-down list labeled Temperature. Select the desired temperature units. All temperature values, such as Test Temperature, Frost Point, Dew Point, etc. will update.
Pressure Units
The current pressure units are indicated in the Units frame in the drop-down list labeled Pressure. Select the desired pressure units. All pressure values, such as Test Pressure and Saturation Pressure, will update.
Vapor Pressure Units
Vapor Pressures may be displayed in units independent of other pressures. The current vapor pressure units are indicated in the Units frame in the drop-down list labeled Vapor Pressure. Select the desired vapor pressure units. All vapor pressure values, such as SVP@Tt, SVP@Td, and SVP@Ts, will update.
Density and Absolute Humidity Units
The current units for Density and Absolute Humidity are indicated in the Units frame in the drop-down lists labeled Density and Abs Humidity. When you select the desired Density and Absolute Humidity units, the values will update.
Enthalpy Units
The current enthalpy units are indicated in the Units frame in the drop-down list labeled Enthalpy. When you select the desired enthalpy units, the enthalpy value will update.
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More About Calculated Values
After the CALCULATE button is clicked, but before calculation, HumiCalc checks your data input. If input values are invalid or questionable, you will receive feedback.
An example of invalid input would be Relative Humidity over 100%. In this case, a Message frame replaces the Calculated Values frame with an appropriate message and a CLOSE button. Change the input value, then retry your calculation.
An example of questionable input would be a Frost Point below -100°C. In this case, a Caution frame replaces the Calculated Values frame with an appropriate message, an OK button, and a CANCEL button. To accept the inputs and calculate, click OK. To not calculate, click Cancel.
Once the calculation is complete, you will see either the Calculated Values frame with a check or question mark, OR a Message frame. If the Message frame appears, a fatal error occurred.
The Calculated Values frame with a check mark indicates a high probability that the given data resulted in reasonable calculations. In other words, the calculated results are within the normal bounds of HumiCalc.
The Calculated Values frame with a question mark indicates a minor problem; that is, a probability that the given data resulted in erroneous calculations. This is usually because a calculated result fell outside the range of HumiCalc's capability. You should be suspicious of data that results in a question mark flag. The cause of these questionable results is generally due to erroneous known values. Click the question mark to bring up the Message frame. Correct your input data and try your calculation again.
For example, a Frost Point Temperature calculating to a value below -100.0 °C could cause the question mark to appear.
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