Technical Service
Anaerobic Chambers FAQs

Below are some frequently asked questions that may be able to answer your needs. If you have any questions please contact us at 734-475-2200. Feel free to email us at TechService@CoyLab.com

Q1. How much gas can I anticipate using when I operate the chamber on a routine basis?

A. This is a difficult question that does not have an exact answer. The exact answer will depend on how many times you enter the Chamber through the airlock. On an average, suppose you entered the Chamber five times a day and were using "K" size supply tanks (304 cubic feet) for nitrogen gas and "A" size supply tanks (230 cubic feet) for the gas mix. If you have an automatic Airlock, your nitrogen gas will last approximately 47 days and your gas mix will last approximately 72 days. These figures assume you are vacuuming the Airlock to 20 inches (0.69 Kg/sq. cm) of mercury. If you have a manual Airlock, your gas mix will last approximately 25 days, assuming you vacuum the Airlock to 29 inches (1 Kg/sq. cm) of mercury. These figures are calculated for Airlock use only. They do not include gas usage during Chamber purges. Test show in a static environment (no airlock operation/transfer) the chambers will consume .2-.4% hydrogen per day.  

Q2. How often, at what temperature and for how long do I rejuvenate my catalyst?

A.  Rejuvenating the Catalyst is very important in keeping the Chamber in an anaerobic condition. Rejuvenating the Catalyst a minimum of once a week at 125-200 Celsius for two hours is recommended. Included in the Chamber package are 2 sets of Catalyst Stak-Pak. Replace the Catalyst you rejuvenate with the extra set. Then your Chamber will always have fresh Catalyst. If you have an extremely busy Chamber, you may need to rejuvenate the Catalyst more frequently.

Q3. Why does my chamber lose its anaerobic condition over a period of time?

A. There are a couple of variables that must be considered to answer this question. First, does your Chamber have a leak? (Noted by the Chamber top collapsing over night.) Second, is the catalyst fresh, have they been rejuvenated?Once these variables have been considered   and eliminated from the probable cause, concentrate on the hydrogen content in the Chamber. Deficient hydrogen content is usually the cause for losing anaerobic conditions in the Chamber. Oxygen is constantly entering the Chamber by Airlock use and diffusion through the PVC walls. Without the hydrogen the catalyst cannot react to remove the oxygen. If you do not regularly use the Chamber, once a week manually vacuum the Chamber about half way and introduce gas mix (containing hydrogen) into the Chamber. You must keep in mind the dilution factor when the gas mix enters the Chamber. If you are using a 10% hydrogen gas mix your Chamber will not contain 10% hydrogen. It will be diluted to approximately 6% or 7% Hydrogen. (see section 2.0). Coy Labs Oxygen/Hydrogen Analyzer can be used to display the amount of hydrogen in percent that is present in your Chamber.    Also, the Analyzer has an alarm that indicates when the hydrogen content goes below 1%. If you have exhausted every probable cause and your Chamber still loses its anaerobic condition, test your gas mix for hydrogen content. We have seen and heard of gas companies that do not comply with customer specifications.  

Q4. How do I know my catalyst is working and how often should I replace it?  

A. A good test to determine if your catalyst is working is to place a tray containing catalyst inside the Airlock. Place a thermometer in direct contact with the catalyst. Then manually vacuum the Airlock (manual or automatic) to 25" (0.53 Kg/sq. cm) of mercury and back fill it with gas mix containing hydrogen. If the catalyst is working correctly, the temperature will increase due to the reaction of catalyst, oxygen, and hydrogen. Temperature will increase about 10 degrees Celsius over 10 to 15 minutes. Coy recommends catalyst replacement on a yearly basis or if the catalyst does not respond to the above test.  

Q5.  Where do most leaks occur in the anaerobic chamber?  

A. Leaks can occur anywhere in the Chamber but most will be present around work areas. Before you begin leak detection, you must first make sure the Chamber contains your normal amount of pre-mixed gas. A towel saturated with isopropyl alcohol, and allowed to sit in the Chamber for a few minutes, will assist in detecting the very small (slow) leaks. With your gas leak detector, check the following areas first:

  1. Gloves and cuffs
  2. Along chamber sleeves
  3. Under work pad
  4. Around airlock seals
  5. All corners of the chamber

AROUND CHAMBER SEAMS

Don't be alarmed if the beeping tone increases around your neoprene rubber gloves. Neoprene rubber has larger pores than PVC so gases diffuse through it faster. Around the gloves, lower the detector sensitivity since the faster diffusion rate will give the appearance of a leak.                  

Q6. What will the hydrogen sulfide produced by sulfur bacteria do to the chamber and how can I control it?

A. It is important to control hydrogen sulfide in the Chamber because it attacks certain metals and can "poison" catalyst. It also accelerates the discoloring of the PVC over time. Hydrogen sulfide is especially detrimental to the oxygen and hydrogen sensors in the Gas Analyzer, and to printed circuit boards in incubators and heated catalyst boxes. These printed circuit boards are coated with a protective substance, but hydrogen sulfide will attack any exposed metal and will, with time, creep under   the coating, thus attacking the metal on the boards. The time taken to affect the metal will depend on the concentration of hydrogen sulfide and the humidity level.

To control hydrogen sulfide within the chamber, use one of the following methods:

  1. Activated charcoal
  2. Lead acetate
  3. Silver chloride
  4. Silver sulfate

For chemicals 2 through 4 the sulfur will bind with the metal forming an insoluble precipitate leaving acetic acid (2 & 3) or sulfuric acid (4) as the byproduct. The activated charcoal will adsorb the hydrogen sulfide molecule. However, we generally DO NOT recommend its use since the adsorption is not specific to hydrogen sulfide,   but is general to most molecules in the Chamber. A specific procedure for the use of silver sulfate is as follows:

  1. Bring 2 liters of distilled water to a boil.
  2. Add 10g of silver sulfate (Ag2O4S) to the boiling water and allow it to dissolve. This will take 5-10 minutes.
  3. After the solution has cooled to near room temperature, add 20 ml of 1 N-aqueous sulfuric acid (H2SO4). This will inhibit the formation of carbonates in the solution.
  4. Add 2 liters of Glycerol (Glycerin) and mix the solution thoroughly.

NOTE: Greater Success is achieved when the Silver Sulfate mix is bubbled with an aquarium pump. This circulates the chamber atmosphere through the silver sulfate making the solution an active part of the chamber rather than passive.  

The glycerol will inhibit evaporation. The solution can be used in the Chamber by bubbling the atmosphere through it or by simply letting a beaker of it sit open in the Chamber. Add water to the vessel if necessary to maintain the initial volume.

The silver sulfide formed is a black precipitate that serves as an indicator that your solution is removing Hydrogen Sulfide from the atmosphere. Over time you will learn what your vessel looks like when all of the silver sulfate has been converted to the precipitate. If you need to test the activity of your solution, you may use sodium sulfide. When put into an active solution the black precipitate, silver sulfide, will form.  

Q7. How do I adjustment the airlock doors?

A. Before making any airlock door adjustments, look at how the door closes. The door only needs to collapse the lip of the seal (7) all the way around to ensure proper door adjustment. This can easily be observed by wiping the seal with a wet cloth, closing the door and looking at the seal through the clear acrylic. If the lip is not collapsed all the way around, the door needs to be adjusted. Door adjustments should be done with the Lock Stud (5) only. To adjust the airlock door use a crescent wrench to turn the lock nut (2) of the lock Stud in very small increments 1/16 of a turn is usually all it takes to tighten the door and collapse the seal. Making larger adjustments should not be necessary, if so it may indicate a problem with another area of the airlock.  

(Image to come)

Q8.   How do I remove the incubator drawer from the chamber?  

A.  Removing the incubator drawer from the chamber can be accomplished 2 ways. The first, and most successful is as follows:                  

  1. With both airlock doors closed, cycle the airlock and tape a large plastic bag to the outside door frame. Make sure the tape is as flat and wrinkle free as possible.
  2. With the incubator drawer removed, open both doors of the airlock. Quickly transfer the incubator drawer through the airlock doors into the plastic bag. After the incubator drawer has cleared the inside door, close it.
  3. Reverse the procedure to install the incubator drawer except close the outside door as soon as the incubator drawer clears.

The second method is to open both airlock doors, quickly slide the incubator drawer through and then close the inside door as soon as the incubator drawer clears. Reverse procedure to install drawer.

Q9. What kind of disinfectant can I use in my chamber?  

A. Coy Labs recommends any of the following three options:

  1. Alcide Brand LD disinfectant has been reported to be satisfactory. It may be applied as a wipe or a spray. Periodic rinsing is suggested with cold water. Available from:
    Alcide Corporation
    8561 154th Avenue, NE
    Redmond
    , WA 98052
    Phone: (425) 882-2555
    Fax: (425) 861-0173
    E-mail: info@alcide. com
  2. With proper care, Isopropyl Alcohol (I. P. A.) or a 1%-2% Clorox solution may also be used. Make sure all excess is wiped off completely.
  3. Peracetic acid may be used to sterilize the chamber.    

Q10.   How can I control the moisture in my chamber?  

A. Moisture is controlled in the chamber by using a desiccant. Coy sells ALUMINA desiccant in bulk or in the Stak-Pak. ALUMINA can be rejuvenated in the same manner as catalyst. If you have severe moisture in your chamber, something is drastically wrong.

Severe moisture can be caused by:

  1. Leak in chamber, catalyst burning up all available hydrogen, and emitting moisture.
  2. Something in the chamber producing moisture.
    (additional information on moisture control, can be found in section 2.3)     

Q11. Why does the fuse keep failing (blowing)?

A.   Usually the fuse will fail when there is a problem with the vacuum pump, which sometimes will also cause a component (the triac) on the PC Board to fail. Check the pump first by unplugging it from the Airlock and plugging into a wall outlet. If the pump works, the triac is most likely the problem and the PCB should be returned for repair. If the pump will not work, use the following procedure. (Refer to the vacuum pump diagram for help).

  1. Remove the two filter elements (8 & 9) from the front of the muffler box (6), and then carefully remove the five bolts holding the muffler box in place. Tap the muffler box gently to loosen it for removal. DO NOT PRY WITH A SCREWDRIVER AS THE GASKET WILL BE DAMAGED. DAMAGED GASKETS WILL LEAK AND CAUSE A POOR VACUUM.
  2. Remove the six bolts holding the end plate (4) to the body (1). Carefully remove the end plate to expose the carbon vanes (2). Carefully remove the vanes from the rotor (*). If the vanes are stuck because of a rust deposit, very carefully remove the rust so the vanes can be moved.
  3. Wipe the body wall with an alcohol cloth to remove any accumulation of rust. Leave the surface clean and dust free so that later the vanes will rotate freely and without damage. Replace damaged vanes.
  4. Reverse this procedure to reassemble
  5. To prevent future trouble, please consider installing the COY Moisture Trap Assembly (No. 7002-050)