Moisture Related Failures Cause, Effect, Solution Daniel R. Schumaier, Ph.D. Ear Technology...
-
Upload
mitchel-greatorex -
Category
Documents
-
view
217 -
download
0
Transcript of Moisture Related Failures Cause, Effect, Solution Daniel R. Schumaier, Ph.D. Ear Technology...
Moisture Related Failures
Moisture Related Failures
Cause, Effect, Solution
Daniel R. Schumaier, Ph.D.
Ear Technology Corporation
We Deal With the Effects of Moisture on
Hearing Aids Every Day
We Deal With the Effects of Moisture on
Hearing Aids Every Day
Corrosion
Switch Problems
Microphone & Speaker Failure
Distortion
Loss of Clarity
Causes of Moisture in Hearing Aids
Causes of Moisture in Hearing Aids
Accidents or Negligence
Cerumen
Perspiration
Environmental Conditions (Condensation) Temperature Humidity
Previous StudiesPrevious Studies 1967, Bruner & House: found RH in
external ear canal always above 60%.
1996, Bailey & Valente: study done for Eveready Battery Co. to determine effect of humidity and temperature on zinc-air battery life. In-vivo studies, majority done at ambient temperature of 60-80 degrees F & RH below 50%.
1999, Agnew (AAS presentation in 4/99): custom ITE worn in right ear, 100 measurements across USA, found that ambient RH and the RH inside the ITE tracked more closely than expected. Therefore, the operating environment inside an ITE was not as extreme as previously assumed.
Nevertheless, moisture causes a huge non-recoverable monetary loss to the industry, and loss of patient satisfaction that ultimately impacts sales.
Relative HumidityRelative Humidity
The ratio of the quantity of water vapor actually present in the air to the quantity that would saturate the air at the existing temperature:
RH = p / psat X 100%
“Relative” means relative to temperature. Warm air holds more moisture than cold air. As the
temperature drops, condensation chances go up.
Dew PointDew PointThe temperature at which the air can
not hold additional moisture at any given temperature (saturated).
Further decrease in temperature will result in condensation.
Condensation ExampleCondensation ExampleWeather Report:
Relative Humidity: 60%Temperature: 90 F
Complicated formula, but in this case the Dew Point is 75 degrees F.
It means that condensation will be formed in the hearing aid even before the hearing aids reach room temperature.
What Do Arizona & Alaska Have in
Common?
What Do Arizona & Alaska Have in
Common?
?Extreme Temperature Changes that Promote
Condensation
What is Needed to Remove Moisture from
Hearing Aids?
What is Needed to Remove Moisture from
Hearing Aids?
Controlled Amount of Heat
Breaks surface tension – smaller drops
Reduces capillary pull (receiver tube)
Reduces the “Glue Effect”
II. Moving Air II. Moving Air
Air circulation initiates natural diffusion effect (wet to dry).
Without controlled airflow, vaporized moisture will re-condense when temperature drops below dew point.
Active systems cause moisture to move out of the hearing aid. Passive systems don’t – except by random chance.
Closed Containers (Hearing Aids) are Difficult to Dry
III. Charged Desiccant
A desiccant is a substance with high affinity for moisture molecules.
Moisture released from the hearing aid must be physically removed, otherwise it will redeposit/condense elsewhere.
Desiccant efficiency is temperature dependent.
Why Not Just Heat the Aid?Why Not Just Heat the Aid?
Heat alone without moisture removal can create a “corrosive soup.”
Warm a small amount of water in a covered pan. When the pan cools, water inside recondenses when the temperature drops through the dew point, dripping off the lid when it is removed.
ConclusionConclusion
Heat (controlled amount)
Moving Air (circulating around the aids)
Desiccant (moisture released must be adsorbed)
3 Things Necessary to Dry a Hearing Aid
Solution: Dry & StoreHearing Aid Conditioning System Three patents Only product to
combine the three needed technologies for drying closed containers
UV light that reduces or ends itching ears or recurring otitis externa
“Dry & Store has greatly improved the quality of my son’s life in the summertime. He was constantly having to get his hearing aids cleaned or repaired because of sweat damage. Thank you! Thank you! Thank you!” F.B., Georgia
“An exceptionally fine product that exceeds the claims made for it.” W.N.C., Florida
“…the unit [Dry & Store] was the key to my feeling comfortable with wearing hearing aids in that it provides a wonderful sanitary place for overnight storage plus the added benefit of drying any wax present to dust… Excellent!” C.S. Brien, Maine
“My aids would be lost withoutDry & Store.” S.L., Athens, Georgia
User Survey Results (5/99)
77% said their hearing aids sounded better.
72% said itching or recurring infections were eliminated or reduced.
54% said batteries lasted longer. 67% said need for repair was
eliminated or reduced. AND…
The Bottom Line…The Bottom Line…
98% of regular Dry & Store users said they were satisfied!
(64.6% said “outstanding”or “very satisfied”)