Today's Message Index:
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1. 10:04 AM - Re: Re: When / where to use dielectric grease? (Robert L. Nuckolls, III)
2. 07:42 PM - Adjustable pot prohibited ? (GTH)
3. 10:46 PM - Re: Re: When / where to use dielectric grease? (rayj)
Message 1
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Subject: | Re: When / where to use dielectric grease? |
At 05:26 AM 1/24/2019, you wrote:
>
>There's a lot of chatter about the use of
>dielectric grease. Permeate suggests that
>Dielectric Tune-Up Grease is a good barrier to
>oxidation at plugs, connectors and
>terminals. There are some online comments at
>forums that say not to place dielectric grease on connector pins.
>
>I've gone to the Permeate site, and the information is vague:
>
>"Protects electrical connections and wiring from
>salt, dirt and corrosion. Extends the life of
>bulb sockets. Prevents voltage leakage around
>any electrical connection. Also prevents spark
>plugs from fusing to boots. Required for modern high energy ignition
systems."
>
>Directions for Connectors: 1. Make sure ignition
>system is off. 2. Clean surface with Permeate
>Contact Cleaner. 3. Coat both parts of terminal
>contact with Dielectric Grease. 4. Reassemble,
>maintaining metal-to-metal contact.
>
>In the PDF, Permatex cites uses for the Permatex Dielectric Tune-Up Grease:
>
>TYPICAL APPLICATIONS
>
>=A2 Spark plug boots
>
>=A2 Distributor cap nipples
>
>=A2 Battery terminals
>
>=A2 Ignition coil connectors
>
>=A2 Headlamp connectors
>
>=A2 Trailer electrical connectors
Dielectric greases and coatings are proven prophylactics
that ward off the effects of adverse environments for
which the potential 'victim' is ill-equipped to
manage on its own.
Borrowing from the assertions of another competent
observer of really big numbers, let us consider what
must be 'billions and billions' of mated conductors
in connectors that have performed over the LIFETIMES
of the target technology with no 'extra' protection
squeezed out of a tube or brushed on from a bottle.
Does this mean that such products have no useful
place? Not at all. My FIRST experience with dielectric
grease moisture protection was 175' up on
a tower where the boss told me that filling the
mated coax connectors with DC4 before assembly
had a demonstrated value for shielding connectors
exposed to Kansas climate way up in the air.
Over the years, I have had occasion to open factory
assembled connectors that were obviously offered
the benefits of protection above and beyond those
offered by the enclosure. This includes lamp sockets
on tail and back-up lights, marker lights and
yes, trailer connectors.
These instances were most common on fixtures
especially exposed to splash or run-down. When
refurbishing equipment that succumbed to
contamination induced corrosion, the
'rule of thumb' called for protecting
the replacement hardware with a good
dielectric grease. But it was also a good
idea to see if some gasket had failed
allowing ingress of moisture.
Emacs!
In years since, designers for electrical
connectors improved designs to improve
performance in harsh environments.
The moisture seal bellows on this
connector is one example.
Emacs!
It's been a long time since I've opened
a connector that contained any previously
applied protection against moisture.
It stands to reason that suppliers of
such products want to sell as much as
the market will purchase. The marketing
problem is that it's seldom necessary/beneficial.
The only time I've used the stuff is
to provide an extra layer of protection
for components that replaced victims
of moisture damage . . . or selected
instances of extra-ordinary risk . . .
like difficult-to-access 175' up on a tower.
The short story is that these products
are best applied during replacement
of parts that have succumbed to moisture
effects. But when such damage is
discovered, be sure to evaluate
the circumstances of the failure.
Was the connector a poor choice to
begin with? Was it subjected to
environmental stresses outside original
design goals? Does a sealing feature of
the enclosure need refurbishment?
I have a 4oz tube of DC4 that is probably
40 years old and barely shows signs of having
been squeezed. Dielectric grease is
a band-aid on a marginal design.
Bob . . .
Message 2
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Subject: | Adjustable pot prohibited ? |
Hello all,
In the past few months I designed for some building buddies a small
electronic device to close a relay when below a certain voltage.
It includes a small multi turn potentiometer to adjust the 13.5 V or
else set point. The device is currently under test.
My intention was, once satisfied with the operation, to seal the
potentiometer with a dab of varnish.
But a friend just tells me that in aviation adjustable pots are
prohibited, and that once adjusted, we should normally replace the
potentiometer with fixed resistors or adequate value.
Does anyone have further information about this rule ?
Thanks,
--
Best regards,
Gilles
http://contrails.free.fr
Message 3
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Subject: | Re: When / where to use dielectric grease? |
I can only comment from my experience on boats and docks. I have seen
less corrosion problems on connections treated with dielectric grease.
The difference can be seen in a matter of a couple of seasons,
especially on ones that are removed and replaced frequently, such as
removable anchor lights and cigar lighter type connectors. Admitted
these are not high buck sealed connections designed for the harsh
maritime environment, but using grease changes them from problematic
designs to being reliable connectors.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 1/25/19 12:03 PM, Robert L. Nuckolls, III wrote:
> At 05:26 AM 1/24/2019, you wrote:
>>
>> There's a lot of chatter about the use of dielectric grease. Permeate
>> suggests that Dielectric Tune-Up Grease is a good barrier to oxidation
>> at plugs, connectors and terminals. There are some online comments at
>> forums that say not to place dielectric grease on connector pins.
>>
>> I've gone to the Permeate site, and the information is vague:
>>
>> "Protects electrical connections and wiring from salt, dirt and
>> corrosion. Extends the life of bulb sockets. Prevents voltage leakage
>> around any electrical connection. Also prevents spark plugs from
>> fusing to boots. Required for modern high energy ignition systems."
>>
>> Directions for Connectors: 1. Make sure ignition system is off. 2.
>> Clean surface with Permeate Contact Cleaner. 3. Coat both parts of
>> terminal contact with Dielectric Grease. 4. Reassemble, maintaining
>> metal-to-metal contact.
>>
>> In the PDF, Permatex cites uses for the Permatex Dielectric Tune-Up
>> Grease:
>>
>> TYPICAL APPLICATIONS
>>
>> Spark plug boots
>>
>> Distributor cap nipples
>>
>> Battery terminals
>>
>> Ignition coil connectors
>>
>> Headlamp connectors
>>
>> Trailer electrical connectors
>
> Dielectric greases and coatings are proven prophylactics
> that ward off the effects of adverse environments for
> which the potential 'victim' is ill-equipped to
> manage on its own.
>
> Borrowing from the assertions of another competent
> observer of really big numbers, let us consider what
> must be 'billions and billions' of mated conductors
> in connectors that have performed over the LIFETIMES
> of the target technology with no 'extra' protection
> squeezed out of a tube or brushed on from a bottle.
>
> Does this mean that such products have no useful
> place? Not at all. My FIRST experience with dielectric
> grease moisture protection was 175' up on
> a tower where the boss told me that filling the
> mated coax connectors with DC4 before assembly
> had a demonstrated value for shielding connectors
> exposed to Kansas climate way up in the air.
>
> Over the years, I have had occasion to open factory
> assembled connectors that were obviously offered
> the benefits of protection above and beyond those
> offered by the enclosure. This includes lamp sockets
> on tail and back-up lights, marker lights and
> yes, trailer connectors.
>
> These instances were most common on fixtures
> especially exposed to splash or run-down. When
> refurbishing equipment that succumbed to
> contamination induced corrosion, the
> 'rule of thumb' called for protecting
> the replacement hardware with a good
> dielectric grease. But it was also a good
> idea to see if some gasket had failed
> allowing ingress of moisture.
>
> Emacs!
>
> In years since, designers for electrical
> connectors improved designs to improve
> performance in harsh environments.
> The moisture seal bellows on this
> connector is one example.
>
> Emacs!
>
> It's been a long time since I've opened
> a connector that contained any previously
> applied protection against moisture.
>
> It stands to reason that suppliers of
> such products want to sell as much as
> the market will purchase. The marketing
> problem is that it's seldom necessary/beneficial.
>
> The only time I've used the stuff is
> to provide an extra layer of protection
> for components that replaced victims
> of moisture damage . . . or selected
> instances of extra-ordinary risk . . .
> like difficult-to-access 175' up on a tower.
>
> The short story is that these products
> are best applied during replacement
> of parts that have succumbed to moisture
> effects. But when such damage is
> discovered, be sure to evaluate
> the circumstances of the failure.
> Was the connector a poor choice to
> begin with? Was it subjected to
> environmental stresses outside original
> design goals? Does a sealing feature of
> the enclosure need refurbishment?
>
> I have a 4oz tube of DC4 that is probably
> 40 years old and barely shows signs of having
> been squeezed. Dielectric grease is
> a band-aid on a marginal design.
>
> Bob . . .
>
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