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Learn something new everyday gofish 01-02-2007
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Posted by Jeffrey Lebowski on January 3, 2007, 10:15 pm

> "geoman" wrote:
>
> >
> >>
> >>>
> >>>> Ok, without looking it up somewhere, at what temperature does the
> >>>> fusible plug blow on the refrigerant system for a R-22 carrier heat
> >>>> pump? (50TJ series)
> >>>>
> >>>> Next question, how in the hell can it get that hot in order to blow
> >>>> out, blowing all the freon into the atmosphere?
> >>>>
> >>>> And last but not least, what is the saturated pressure of r-22 at
that
> >>>> temp??
> >>>
> >>>If I recall, Fusible plugs really are not for pressure relief due to a
fan
> >>>failure or plugged condenser. A mechanical relief valve is meant for
that.
> >>>A fusible plug is really designed for a unit located in a fire. This
would
> >>>allow the refrigerant to blow off before an excessive amount of
pressure
> >>>could rupture the receiver/system and cause injury or death. Its true
that
> >>>they sometimes fail due to high pressures but originally it was a UL
thing
> >>>for fire, If I recall my facts correctly. I can look at my old Sam's if
> >>>this
> >>>discussion goes further.
> >>>
> >>>Rich
> >>>
> >> Rich,
> >> Ive not heard that one but I have seen a lot of Carriers and Bryants
> >> with blown fuseable plugs. Always found them on outdoor units with bad
> >> cond motors, leaking suction accumulators, leaking evap or condenser
> >> coils or screwed up rev valves. Never saw one in a fire yet.
> >> Bubba
> >
> >Maybe Carrier, (WHICH btw is very possible) has it on their units for low
> >temp release. But I'm very very sure (99.9%) that in refrigeration they
> >mostly are for fire and shipping. Shipping is a big thing as well, a
vessel
> >that carries so many pounds of refrigerant must have a relief that if
fire
> >hits it the unit will release verses explode.
> >
> >I've seen them on Carriers too, on the discharge line if I recall, but
never
> >found one that leaked.
> >
> >I'll see if I can even find my books on the subject and if I do I'll look
it
> >up. Maybe AC and Refrigeration is different.
> >
> >
>
> Rich,
>
> I've seen these plugs ONLY on carrier products, ie Bryant, Carrier,
> Day & Night, BDP etc. On the older models they're mounted between the
> accumulator & comp in the copper tubing, the one that blew was located
> on the top of the accumulator. Rated to blow at 210F. In my case
> the rev valve is stuck half way between ht & cool. Natchurly I didnt
> find that out until i evacuated and dropped in a charge. :(
>
> fyi- <most> fusible links (fire dampers, smoke dampers) etc melt at
> 165F.

http://en.wikipedia.org/wiki/Cerrobend

--




Posted by on January 4, 2007, 2:02 am

>
>> "geoman" wrote:
>>
>> >
>> >>
>> >>>
>> >>>> Ok, without looking it up somewhere, at what temperature does the
>> >>>> fusible plug blow on the refrigerant system for a R-22 carrier heat
>> >>>> pump? (50TJ series)
>> >>>>
>> >>>> Next question, how in the hell can it get that hot in order to blow
>> >>>> out, blowing all the freon into the atmosphere?
>> >>>>
>> >>>> And last but not least, what is the saturated pressure of r-22 at
>that
>> >>>> temp??
>> >>>
>> >>>If I recall, Fusible plugs really are not for pressure relief due to a
>fan
>> >>>failure or plugged condenser. A mechanical relief valve is meant for
>that.
>> >>>A fusible plug is really designed for a unit located in a fire. This
>would
>> >>>allow the refrigerant to blow off before an excessive amount of
>pressure
>> >>>could rupture the receiver/system and cause injury or death. Its true
>that
>> >>>they sometimes fail due to high pressures but originally it was a UL
>thing
>> >>>for fire, If I recall my facts correctly. I can look at my old Sam's if
>> >>>this
>> >>>discussion goes further.
>> >>>
>> >>>Rich
>> >>>
>> >> Rich,
>> >> Ive not heard that one but I have seen a lot of Carriers and Bryants
>> >> with blown fuseable plugs. Always found them on outdoor units with bad
>> >> cond motors, leaking suction accumulators, leaking evap or condenser
>> >> coils or screwed up rev valves. Never saw one in a fire yet.
>> >> Bubba
>> >
>> >Maybe Carrier, (WHICH btw is very possible) has it on their units for low
>> >temp release. But I'm very very sure (99.9%) that in refrigeration they
>> >mostly are for fire and shipping. Shipping is a big thing as well, a
>vessel
>> >that carries so many pounds of refrigerant must have a relief that if
>fire
>> >hits it the unit will release verses explode.
>> >
>> >I've seen them on Carriers too, on the discharge line if I recall, but
>never
>> >found one that leaked.
>> >
>> >I'll see if I can even find my books on the subject and if I do I'll look
>it
>> >up. Maybe AC and Refrigeration is different.
>> >
>> >
>>
>> Rich,
>>
>> I've seen these plugs ONLY on carrier products, ie Bryant, Carrier,
>> Day & Night, BDP etc. On the older models they're mounted between the
>> accumulator & comp in the copper tubing, the one that blew was located
>> on the top of the accumulator. Rated to blow at 210F. In my case
>> the rev valve is stuck half way between ht & cool. Natchurly I didnt
>> find that out until i evacuated and dropped in a charge. :(
>>
>> fyi- <most> fusible links (fire dampers, smoke dampers) etc melt at
>> 165F.
>
>http://en.wikipedia.org/wiki/Cerrobend


??

Posted by Jeffrey Lebowski on January 4, 2007, 2:18 am

>
> >
> >> "geoman" wrote:
> >>
> >> >
> >> >>
> >> >>>
> >> >>>> Ok, without looking it up somewhere, at what temperature does the
> >> >>>> fusible plug blow on the refrigerant system for a R-22 carrier
heat
> >> >>>> pump? (50TJ series)
> >> >>>>
> >> >>>> Next question, how in the hell can it get that hot in order to
blow
> >> >>>> out, blowing all the freon into the atmosphere?
> >> >>>>
> >> >>>> And last but not least, what is the saturated pressure of r-22 at
> >that
> >> >>>> temp??
> >> >>>
> >> >>>If I recall, Fusible plugs really are not for pressure relief due to
a
> >fan
> >> >>>failure or plugged condenser. A mechanical relief valve is meant for
> >that.
> >> >>>A fusible plug is really designed for a unit located in a fire. This
> >would
> >> >>>allow the refrigerant to blow off before an excessive amount of
> >pressure
> >> >>>could rupture the receiver/system and cause injury or death. Its
true
> >that
> >> >>>they sometimes fail due to high pressures but originally it was a UL
> >thing
> >> >>>for fire, If I recall my facts correctly. I can look at my old Sam's
if
> >> >>>this
> >> >>>discussion goes further.
> >> >>>
> >> >>>Rich
> >> >>>
> >> >> Rich,
> >> >> Ive not heard that one but I have seen a lot of Carriers and Bryants
> >> >> with blown fuseable plugs. Always found them on outdoor units with
bad
> >> >> cond motors, leaking suction accumulators, leaking evap or condenser
> >> >> coils or screwed up rev valves. Never saw one in a fire yet.
> >> >> Bubba
> >> >
> >> >Maybe Carrier, (WHICH btw is very possible) has it on their units for
low
> >> >temp release. But I'm very very sure (99.9%) that in refrigeration
they
> >> >mostly are for fire and shipping. Shipping is a big thing as well, a
> >vessel
> >> >that carries so many pounds of refrigerant must have a relief that if
> >fire
> >> >hits it the unit will release verses explode.
> >> >
> >> >I've seen them on Carriers too, on the discharge line if I recall, but
> >never
> >> >found one that leaked.
> >> >
> >> >I'll see if I can even find my books on the subject and if I do I'll
look
> >it
> >> >up. Maybe AC and Refrigeration is different.
> >> >
> >> >
> >>
> >> Rich,
> >>
> >> I've seen these plugs ONLY on carrier products, ie Bryant, Carrier,
> >> Day & Night, BDP etc. On the older models they're mounted between the
> >> accumulator & comp in the copper tubing, the one that blew was located
> >> on the top of the accumulator. Rated to blow at 210F. In my case
> >> the rev valve is stuck half way between ht & cool. Natchurly I didnt
> >> find that out until i evacuated and dropped in a charge. :(
> >>
> >> fyi- <most> fusible links (fire dampers, smoke dampers) etc melt at
> >> 165F.
> >
> >http://en.wikipedia.org/wiki/Cerrobend
>
>
> ??

Link to various low melt point alloy and showing actual melting temps.

( Thought wouldn't hurt to divulge...little trade secret...esp beings as
someone was suggesting just the other day to fill tubing with sand prior to
bending ).

--






Posted by Mark on January 4, 2007, 10:38 am


> If I recall, Fusible plugs really are not for pressure relief due to a fan
> failure or plugged condenser. A mechanical relief valve is meant for that.
> A fusible plug is really designed for a unit located in a fire. This would
> allow the refrigerant to blow off before an excessive amount of pressure
> could rupture the receiver/system and cause injury or death.

If there were a fire, would not the mechnical pressure relief open and
blow off the pressure before the pressure could build to repture level
as well even without a fusible plug??

Mark


Posted by Bubba on January 2, 2007, 8:01 pm
On Wed, 03 Jan 2007 00:46:10 GMT, gofish@gonefishin.net wrote:

>Ok, without looking it up somewhere, at what temperature does the
>fusible plug blow on the refrigerant system for a R-22 carrier heat
>pump? (50TJ series)
>
>Next question, how in the hell can it get that hot in order to blow
>out, blowing all the freon into the atmosphere?
>
>And last but not least, what is the saturated pressure of r-22 at that
>temp??

Dont actually know the temps but dont care or matter either. Its an
old one. They usually blew because the coils or elsewhere were leaking
refrigerant. The unit runs hot, the plug melts and out goes the
refrigerant. Rretty stupid design but very cheap to make. As usual,
Carrier's engineering that says, "Screw the customer. We will protect
our compressor. We dont care what it costs the customer to repair."
Bubba

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