With continued use of the Inhalation Tower, some parts will wear out and may need to be replaced. Proper care and maintenance will help ensure consistent results and that the equipment investment will last for years.  This information can also be found in the Inhalation Tower Application Manual.

Consider replacing/servicing the following components on a scheduled basis:

• Tubing
• Pneumotach Screens
• O-rings
• Nebulizers

The frequency of replacement will depend on a variety of factors that may include: testing environment, frequency

of use, aerosol exposure, and proper care of equipment throughout. Good Laboratory Practices (GLP) and routine

equipment maintenance/servicing are recommended. At a minimum, tubing and screens should be replaced

annually. 

Maintenance Kits

Maintenance kits are available for the Inhalation Tower and all the adapters/accessories that connect to it. This section will provide an outline of the various kits, their part numbers, and what’s contained in each.

Basic Chamber Accessory Tool Kit

The Basic Chamber Accessory Tool Kit provides the necessary tools required for routine maintenance.

• Replacement part number: 601-2524-064

The tool kit consists of the following items:

Tubing

This section details the various tubing that may need to be replaced on the Inhalation Tower System. Replace tubing when it becomes visibly clogged or cloudy with aerosol deposition. Tubing should be free from cracks, moisture, and deposits.

Replacement part number: 601-6103-002

Includes the following tubing:

1. Inflow tube
2. Outflow tube
3. Tower Balance tube
4. Quick-Disconnect Tube Plugs (012402-001, Qty: 5)

Filters and In-line Dryer Tubes

The filters and in-line dryer tube silica gel used with the tower and controllers will need to be replaced with extended use:

Reusing the In-line Dryer Tube Silica Gel Beads

The In-line Dryer tube uses reusable Silica gel beads that change color to indicate the level of moisture drawn out of the inflow air. As the beads become saturated, they will change from blue to pink. Another indication that the beads need to be dried or changed is when the inflow humidity begins to climb higher than expected or cannot be maintained. Once this occurs, the beads must be removed to go through the drying process.

To remove the Silica gel beads from the in-line dryer tubes:

• Disconnect any tubing connected to the in-line dryer tubes’ end caps.
• Rotate the end cap counter clockwise to release the pin.

• Pull end cap out.
• Pour Silica gel beads out of dryer tube.
• Add new Silica gel beads into dryer tube.
• Replace end cap.
• Rotate end cap clockwise to lock pin in place.

Drying process:

To reuse the silica gel, set an oven to 255⁰F, ~120⁰ C, pour the silica gel beads into a flat pan, and heat until the beads turn blue again (~12 hours). When they are completely cooled down, they may be reused with the in-line dryer.

Diffusion Dryer - Reusing the Silica Gel Beads

The Diffuser Dryer is used to reduce moisture from the air flow prior to distribution throughout the tower. As moisture is drawn out of the air flowing through the Diffuser Dry, the color of the Silica gel changes. The Silica gel beads used in the Diffuser Dryer are originally yellow in color. When the beads turn clear, they must go through the drying process. Another indication that the beads need to be dried is when the tower humidity begins to climb higher than expected or cannot be maintained.

To reuse the silica gel, set an oven to 255⁰F, or 120⁰C, pour the silica gel beads into a flat pan, and heat until the beads turn yellow again (~1-2 hours). When they are completely cooled down, they may be reused in the Diffuser Dryer.

Note: there should not be any dust on the beads at this point. Therefore, there is no need to blow house air through the Diffuser Dryer once the beads are reloaded, as the Filling the Dryer outlines for first time use. Please see the Filling the Dryer for more details.

Restraint and Plethysmography Maintenance Kits

Restraint and Plethysmography maintenance kits provide replacement parts for the particular chambers being used. These kits include the following:

The following table outlines the available kits and their ordering information by animal size:

Note: Kits contain additional components that are not discussed in this section. Components may differ based on species and the type of chamber used.

O-rings

O-rings provide a seal between two removable components. O-rings should be free from cracks, debris, and excessive wear. If additional O-rings are required for replacement, please see the appropriate Maintenance Kits section for the particular item on which the O-ring is attached for details on the necessary kit.

• Silicone Lubricant part number: 601-2524-052

Nose/Neck Seals

Nose/neck seals prevent air leaks between the restraint and the animal. Seals should be free from cracks and excessive wear. 

Replacement seals are available in the restraint maintenance kits. Please see the

section. Alternatively, they may be purchased individually should you only need the seals:

• Mouse Seals (QTY: 12)
  • 601-2520-002 (standard size)
  • 601-2521-002 (thicker size)
  • 601-2512-011 (standard size, small hole – 0.25”)
• Rat Seals (QTY: 12)
  • 601-2520-004
• Hartley Guinea Pig (QTY: 10 neck seals and 10 nose seals.)
  • 601-6118-001
• Ferret (uses same seal as the Hartley Guinea Pig)
  • 601-6118-001

Pneumotach Screens

This section details the process used to replace pneumotach screens from the plethysmograph chamber. These fine mesh screens mounted in the plexiglass pneumotachographs on the side of the animal chamber provide the stable resistance elements necessary to accurately monitor the breathing waveform of the animal. The resistance element is part of the transducer/preamplifier circuit that when calibrated, provides a waveform that the software analyzes during the course of the experiment. When these screens become contaminated due to environmental dust and ordinary usage over an extended period, the resistance provided by the screens can change. As the resistance of the screens change, the effective range obtained during calibration will change. When the effective range begins to shrink, this is a good indication that the pneumotach screens are dirty and should be replaced.

Screen Replacement

To replace the pneumotach screens:

1. Use a hex wrench to remove the four stainless steel screws that hold the pneumotachograph cover in place.

2. Remove the cover, tilt the plethysmograph, and the screens should fall out. Note the number of screens removed. In normal use, only the screens attached to the animal side need to be replaced.
3. If necessary, remove and replace pneumotach O-rings.
4. Insert the identical number of new screens using the provided tweezers.
5. Replace the pneumotach covering and screw it back into place

Replacement pneumotach screens are part of the plethysmography maintenance kits mentioned in the

Allay Collar Kits

Additional Allay collars are available. This section details the different Allay Collar Options by species/restraint type: