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Q: Tumble dryer operating temperature ( Answered 3 out of 5 stars,   2 Comments )
Question  
Subject: Tumble dryer operating temperature
Category: Science > Physics
Asked by: dryerman-ga
List Price: $50.00
Posted: 16 May 2006 09:30 PDT
Expires: 15 Jun 2006 09:30 PDT
Question ID: 729373
What temperature is the inside of an operating tumble dryer?  I am
trying to understand the range of temperatures that an item
(particularly PVC) inside a tumble dryer might reach after, say, 120
minutes on the "hottest" cycle.  I know that this will vary with the
condition of the machine so a good answer would give me a "typical"
temperature and also the temperature if all the lint traps etc. were
blocked so that the machine was over-heating.
Answer  
Subject: Re: Tumble dryer operating temperature
Answered By: leapinglizard-ga on 16 May 2006 11:15 PDT
Rated:3 out of 5 stars
 
Dear dryerman,


Under normal operating conditions, the hot air blown into a clothes
dryer's tumbler reaches a temperature of about 175 degrees Celsius.


     Another air temperature of interest is at the tumbler intake. The
     air temperature in this area rose to about 175C during normal
     operation [see Figure 1].

Appliance Magazine: Detection of Abnormal Operating Conditions in Electric
Clothes Dryers
http://www.appliancemagazine.com/amag/editorial.php?article=521&zone=1&first=1


If the lint traps are blocked and the thermostat fails, the resulting
unregulated temperatures have been shown to exceed 400 degrees Celsius.


    In FY 2002, U.S. Consumer Product Safety Commission staff
    completed a test program to evaluate residential electric clothes
    dryers under various test conditions. The test program included
    measurements of temperature and airflow characteristics for
    different electric clothes dryer designs under normal operating
    conditions and conditions of partially-blocked and fully-blocked
    exhaust ducting. [...]


    3.2.1 Normal Operation (Unblocked Exhaust Vent)

        When the dryers were tested with an unblocked exhaust
        vent, similar temperatures ?- the intake air temperature
        into the heater, the heater housing temperature, the
        intake air temperature into the blower, and the exhaust
        vent temperature -? were measured among all dryer
        designs. [...]


    3.2.2 Partially-Blocked and 100%-Blocked Conditions

        Each dryer design reacted slightly differently when 
        the exhaust vent was partially blocked and/or 100%
        blocked. [...]

        Figure 81 shows the range of highest to lowest maximum
        temperatures at the intake into the tumbler for each test
        condition. The temperature curves shown in this graph
        are similar to those for the heater exhaust (Figure 
        77), except that the maximum temperature measured 
        when the exhaust vent was fully blocked was lower ?
        approximately 400C.

U.S. Consumer Product Safety Commission: Final Report on Electric Clothes
Dryers and Lint Ignition Characteristics
http://www.cpsc.gov/library/foia/foia03/os/dryer.pdf


A diagram on page 105 of the CPSC report (page 118 of the PDF document)
shows the various places where temperatures can be measured inside a
dryer. Because a sensor cannot be placed inside the tumbler itself,
the nearest location for measuring the temperature inside the tumbler
is T6, the tumbler intake. It is here that the normal temperature of
about 175C and the maximum temperature of 400C were observed.


It has been an interesting challenge to answer your question. If you have
any concerns about the accuracy or completeness of my research, please
advise me through a Clarification Request and allow me the opportunity
to fully meet your needs before you rate this answer.

Regards,

leapinglizard


Search strategy:

clothes dryer temperature degrees
://www.google.com/search?q=clothes+dryer+temperature+degrees

://www.google.ca/search?q=laundry+dryer+temperature+limit
laundry dryer temperature limit

Request for Answer Clarification by dryerman-ga on 18 May 2006 07:35 PDT
Thank you leapinglizard.  Sorry for the late response but the
auto-notify seems not to be working so I wasn't aware anyone had
answered.

I had already come across the US Product Safety commission report
(although the Appliance Magazine article was new to me).

However, it was particulalrly the temperature of items inside the
dryer rather than the air temperature entering and exiting that is of
interest to me.

Maybe air temperature is the best I can get but I was hoping for
something more.  Surely fabric manufacturers have tested to see how
hot their clothes get before they shrink/ruin etc.?

Clarification of Answer by leapinglizard-ga on 19 May 2006 13:15 PDT
The items in a dryer cannot reach a higher temperature than the air
surrounding them, so at least you have an upper limit. The air
temperature inside the tumbler must be somewhere between the intake
and exhaust temperatures. You raise an interesting point about the
heat resistance of fabrics, but I'm afraid I haven't found any exact
numbers on this.

leapinglizard
dryerman-ga rated this answer:3 out of 5 stars
The answer was useful but did not answer the specifics of the question.

Comments  
Subject: Re: Tumble dryer operating temperature
From: iang-ga on 16 May 2006 10:06 PDT
 
Domestic dryers go up to about 90 deg C.  That's a regulated
temperature, so blockages shouldn't have much effect.  If the
thermostat fails I suppose all bets are off!

Ian G.
Subject: Re: Tumble dryer operating temperature
From: neilzero-ga on 22 May 2006 10:51 PDT
 
My guess is an error has occured. Some faberics would be badly damaged
by 175 c and nearly all faberics by 400 degrees c = 753 degrees f.
Painful burns would reward the person who tried to remove the clothing
just before the cool down cycle. The 90 degrees c = 194 degrees f.
seems more reasonable. Neil

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