Frequently Asked Questions

If there are any questions about the F-900, please check the Frequently Asked Questions below, as well as the Felix Instruments support webpage at http://felixinstruments.com/support/f-900-support.

1. What type of fruit produces ethylene?
   • Climacteric fruits refer to fruits that have high respiration rate during the fruit's ripening. During the ripening process of climacteric fruits, the production of a phytohormone, ethylene, dramatically increases up to 1000-fold of the basal ethylene level. Climacteric fruits are ones that are able to ripen after being picked. An example of climacteric fruit is bananas; they are picked and shipped green and then ripen at a later time (often in the store or home). Climacteric fruits include, but are not limited to, apples, apricots, avocados, bananas, cantaloupes, figs, guavas, kiwis, mangoes, nectarines, peaches, pears, persimmons, plums, and tomatoes. [Source: Wikipedia.com]
2. What should I do if I see moisture develop in the tubing when monitoring a fruit in the chamber?
   • There is a protective hydrophobic filter inside the IN port on the front of the F-900. This will prevent moisture from fully entering the instrument. Silica gel in a conditioning chamber can be used to dry out the gas stream, either before or after the gas passes the electrochemical sensor. Refer to the flow path diagram in the Setup>Chamber section of the User Manual for more information.
3. Can the data output be directly linked to the computer, and by what type of connection can be used? And is it MAC and/or PC compatible?
   • The unit has an SD card and the format can be read on any Mac or PC. Data can also be downloaded via USB. The F-900 Controller software is used when connecting to a PC to view real-time data (see page 2 for more details.)

4. How do I change how the data appears in the .csv file?

   • If data isn't displaying properly, try saving the file as a .csv file type and re-opening it. If saving as a .csv does not fix how the data is displayed, you may need to change the separator value on your computer.
     To change the separator in all .csv text files:

     1. In Microsoft Windows, click the Start button, and then click Control Panel.

     2. Open the Region and Language Options dialog box.

     3. Do one of the following:

        • In Windows Vista and 7, click the Formats tab, and then click Customize this format. In Windows 7 click the "additional settings" button to get to the option to change the separator.

        • In Windows XP, click the Regional Options tab, and then click Customize.

     4. Type a new separator in the List separator box. For example, type ","

     5. Click OK twice.

     NOTE: After you change the list separator character for your computer, all programs use the new character as a list separator. You can change the character back to the default character by following the same procedure.

5. How do I create and open a file to start using the F-900?

   • To start using the F-900, create a file to save data into. Go to File>Create. Change the file00 to the desired file-name and press save. Next, open the file to save measurements. Go to File>Open and use the arrows to highlight the newly created file. If the value next to the file-name is a negative number, this indicates an error. You should delete the file and create it again. Then, open it and check that the value is zero. Now, you can save data into this file.
6. What consumables come with the F-900?
   • The F-900 and F-900RK ship with potassium permanganate (KMnO₄), an ethylene scrubber (Purafil Fresh Air Sachets). KMnO₄ is sold at many Home and Garden stores and online. The pellet (vs. crystal or powder) form of KMnO₄ is recommended. http://www.producefreshies.com/ is an online source.
   • The F-900RK also ships with a humidity scrubber (silica gel). If the F-900 includes an optional CO₂ sensor, soda lime is provided as a CO₂ scrubber. Carolina Biological (www.carolina.com) is an online source for soda lime and silica gel.
7. What are some possible applications for the F-900?
   • The F-900 could be used to help optimize Controlled Atmosphere Storage Rooms and prevent losses. Ethyleneis an important and sensitive marker for ripening of fruits. Other postharvest research applications are possible.
   • In addition to plants, some microorganisms, including fungi and bacteria, synthesize ethylene. Microorganisms can cause great losses in the postharvest industry through disease and mold, so research into ethylene and the pathogen-host interaction is important. A common plant pathogen that produces ethylene is Botrytis cinerea.
   • Measuring ethylene concentration in the air of rooms where young apple trees in pots are stored adjacent to refrigerated apple storage rooms, in order to assess the safety to young apple trees. During the winter months, the safe level for storage of first year apple trees is below 50ppm.
   • Commercial apple growers could monitor the ethylene levels of empty refrigerated rooms before storing bare-root nursery trees. Rooms should be empty of ethylene before storing nursery trees and often growers have no way to monitor this.
   • Monitoring ethylene emission from industrial sources. Ethylene is of interest because it plays a role in atmospheric ozone chemistry. This will be dependent on interfering gas and the source of industrial emissions.
8. How long does it take to recharge the battery?
   • About four hours. The unit may be operated while the battery is charging.
9. What happens if the cell runs out of water?
   • If the cell runs out of water, the lead electrode could undergo sulfation. This would affect the sensitivity by reducing the active area on the lead electrodes. It is more likely that a lack of water in the cell decreases the activity of the electrolyte and increases the resistivity of the Nafion membrane. Both will affect the background current and response time of the cell.
10. What are the advantages of the F-900RK over the standard F-900?
    • Both are portable, but the research kit includes the other components as listed in the “Unpacking the F-900” section of the User Manual, such as the fruit chamber and wand and hard-sided, wheeled carrying case. The Research Kit is designed to make measurement of fruits non-destructively or in a closed chamber. Fans are built into the fruit chamber to mix the air.
11. What are the most commons uses for Chamber In and Chamber Out?
    • Both chambers are optional, but it is recommended to use Chamber In as PolarCept for most measurements. The most common use for Chamber In is to separate light hydrocarbons, such as alcohol, from the gas stream which may interfere with the measurement. The most common use for Chamber Out is to be filled with potassium permanganate, so that it cleans all ethylene and other hydrocarbons from the gas stream, so that any ethylene that is measured must have come from the sample. Chamber Out is also commonly used with KMnO₄ to calibrate the zero of the ethylene sensors.
12. During a monitoring experiment, will the sealed fruit chamber influence the result as time goes on?
    • The air should be scrubbed by enabling conditioning Chamber Out (filled with potassium permanganate). Attach the tubing from the wand that returns to the fruit chamber to the Out port on the front of the F-900.
13. Where are temperature and humidity measured?
    • The temperature and relative humidity sensors are located inside the F-900, before the electrochemical sensor. There is an additional relative humidity sensor after the ethylene sensor to help track water loss.

14. What is the emission rate of ethylene from the fruit, taking into account the weight of the fruit (or sample) and the time measured?

    • Flow rate: 0.2L/min = 12.0L/hr

      Sensitivity of C₂H₄ PPM sensor to C₂H₄: 0.1 µL/L or 100 nL/L

      Therefore, the F-900 optimally detects around 1200 nL/hr. The unit is nanoliters of ethylene per gram fresh weight per hour.

15. What types of tubing materials have been found to outgas?

    • Several types of material have been found to outgas interfering gases of the ethylene sensor, such as Tygon. Viton and Teflon have successfully been found to not outgas.