Microwave oven testing?

[Wayne B. Wilson]

I use a tester then a cup of water to check for leaks around the door if the light blinks in all zones then i good to go. The water is usually hot after i check the door for leaks.
Warranty companies love to hang home inspectors . Gets them out of claims. Past the old buck.

[Wayne B. Wilson]

Originally Posted by escanlan

A hamster wrapped in electrical tape on high for 3.5 minutes. If it cooks without exploding it passes.

I do like this idea though

[jvogan]

Originally Posted by mnahrgang

What are these things filled with? I was using mine yesterday and it started to pop like a bag of popcorn. Smelled like it too.

Mine's never popped, but it sure smells like popcorn!

Barry, I am at a loss...I don't know what you can do to "measure" how well the unit is working. I just check for leaks and see if it warms up the tribble...it is hard to quantify how well a microwave is working. Hope it works out for you and your client.

[klott]

I don't care how well they heat, the most important test is a leak test, and it can only be performed a meter by a Certified Microwave technician. Anything over leakage .0025 Picocuries is unsafe. Most leak around the door seal, and if you see any cracks anywhere, it is an automatic failure. Any of the old Amana Radar ranges, leak like a sieve and are known to cause cancer in any home owner unfortunate enough to have owned one of the originals. As a matter of fact, heating and cooking by microwaves was discovered by a Radar operator at an Air Force installation, who had a sandwich in the pocket of his Smock, about waste high, the sandwich got hot, hence the original name for the Amana Radar Range. I suggest you include language in your reports that you tested for operation only, and recommend a leak detection test by a qualified Appliance Tech with the appropiate certification, to CYA. P.S. Never stand in front of one that is in operation.

[Doug Edwards]

I have my assistant who has a pacemaker stand next to the unit. If he goes tits up after a few seconds I know there is a problem. He hates doing this and always groans when he sees a built in microwave.

[klott]

Originally Posted by dedwards

I have my assistant who has a pacemaker stand next to the unit. If he goes tits up after a few seconds I know there is a problem. He hates doing this and always groans when he sees a built in microwave.

At least you didn't say friend!

[David A. Andersen]

Testing the oven - the water heating test

The precise number of degrees a known quantity of water increases in
temperature for a known time and power level is a very accurate test of
the actual useful microwave power. A couple of minutes with a cup of
water and a thermometer will conclusively determine if your microwave
oven is weak or you are just less patient (or the manufacturer of your
frozen dinners has increased their weight - sure, fat chance of that!)
You can skip the heavy math below and jump right to the final result
if you like. However, for those who are interested:
* 1 Calorie (C) will raise the temperature of 1 gram (g) of liquid water
exactly 1 degree Centigrade (DegC) or 9/5 degree Fahrenheit (DegF).
* 1 Calorie is equal to 4.184 Joules (J) or 1 J = .239 C.
* 1 Watt (W) of power is 1 J/s or 1 KW is 1000 J/s.
* 1 cup is 8 ounces (oz) which is 8 x 28.35 g/oz = 226.8 g.
* 1 minute equals 60 s (but you know this!).
Therefore, in one minute, a 1 KW microwave oven will raise the temperature
of 1 cup of water by:
T(rise) = (60 s * 1000 J/s * .239C/J * (g * DegC)/C)/(226.8 g) = 63 DegC.
Or, if your prefer Fahrenheit: 114 DegF.
To account for estimated losses due to conduction, convection, and imperfect
power transfer, I suggest using temperature rises of 60 DegC and 109 DegF.
Therefore, a very simple test is to place a measured cup of water in the
microwave from the tap and measure its temperature before and after heating
for exactly 1 minute on HIGH. Scale the expected temperature rise by the
ratio of the microwave (not AC line) power of your oven compared to a 1 KW
unit.
Or, from a Litton microwave handbook:
Heat one Liter (L) of water on HIGH for 1 minute.
Oven power = temperature rise in DegC multiplied by 70.
Use a plastic container rather than a glass one to minimize the needed
energy loss to raise its temperature by conduction from the hot water.
There will be some losses due to convection but this should not be that
significant for these short tests.
(Note: if the water is boiling when it comes out - at 100 DegC or 212 DegF,
then the test is invalid - use colder water or a shorter time.)
The intermediate power levels can be tested as well. The heating effect of
a microwave oven is nearly linear. Thus, a cup of water should take nearly
roughly twice as long to heat a specific number of degrees on 50% power or
3.3 times as long on 30% power as on full power. However, for low power
tests, increasing the time to 2 minutes with 2 cups of water will result
in more accurate measurements due to the long period pulse width power
control use by microwave ovens which may have a cycle of up to 30 seconds.
Any significant discrepancy between your measurements and the specified
microwave power levels - say more than 10 % on HIGH - may indicate a problem.
(Due to conduction and convection losses as well as the time required to
heat the filament of the magnetron for each on-cycle, the accuracies of
the intermediate power level measurements may be slightly lower).

[William Thacker]

Originally Posted by klott

I don't care how well they heat, the most important test is a leak test, and it can only be performed a meter by a Certified Microwave technician. Anything over leakage .0025 Picocuries is unsafe.

is picocuries the right unit? a curie is a measure of radioactive decay.

[Bob Elliott]

Originally Posted by gromicko

Dang it Manny!, now everyone knows the secret to making the tribbles: http://www.nachi.org/tribbles.htm

i got two of them from you so far and like the faint popcorn smell.
Works great.

Takes only 15 sec to get warm.
The above needs to not leave the bag in so long.

[tdietrich1]

Can we still get tribbles? Been a little cold. I bet they feel good in your pockets.

tom

[Brian E. Kelly]

Originally Posted by mboyett

Barry,
95% of the microwave ovens I encounter are built-in and usually include the range hood and stove light. I use Mr. Microwave Magic Lights for $6 ea from http://www.electronix.com/catalog/pr...oducts_id/5445
Attachment 17099

That is what I use also.

And Barry, why do you care what some fly by night warranty company will cover????

[kpierce]

Originally Posted by bkelly2

That is what I use also.

And Barry, why do you care what some fly by night warranty company will cover????

I don't think Barry will be responding.