Buzzard's Roost

Technology has changed so quickly in my lifetime, I keep wondering what it will be like in the next 60 years long after I am gone. Microwave ovens have come a long way since the 1970’s. Let me explain briefly, what you need to know.

There is an electromagnetic spectrum, and it is composed of radio waves, microwaves, gamma rays, and visible light. The only thing to remember is that it is not radioactive like uranium and plutonium. Microwave generators exist in many aspects of your everyday life, even as simple as the seam of a plastic bag.

Microwaves range between 10 – 300,000 megahertz (MHz). To be more specific, the wave oscillates or vibrates, up to 300,000 million times per second. Microwave radiation exists elsewhere as well (i.e. FM radio antennas, TV antennas, radar units, and of course, your cell phone generates some as well). You remember all those cell phone towers standing boldly in the countryside. EMF (Electromagnetic Field) and EMI (Electromagnetic Interference) are commonplace in today’s society. Electrical power lines generate radiation into the atmosphere. How often do you travel near high tensions wires and find your car radio goes crazy with static noise.

What is important is the higher the frequency of the microwave, the lower the health hazard potential. You can see a typical microwave oven in Diagram 1. The magnetron tube generates the microwaves in unison with the stirrer. It actually vibrates the water molecules in the food and when this occurs, the molecules vibrate and bang into each other causing frictional heat. The heat warms or cooks the food for the set duration of time.

Diagram 1

OSHA (Occupational Safety and Health Administration) along with FDA (Federal Drug Administration) has put safety limits on home and business microwave ovens. The radiation limit is set at one milliwatt per square centimeter (1 mw/c2) at a distance of five (5) centimeters from the microwave door.

With all the general information in your memory, let me talk to you about your microwave oven and give you a little more detail. You notice there is usually a window in every oven, so you can see the food boil or cook. Every microwave has a different wattage for cooking, depending on its size. If your regular oven varies with temperature and time for recipes that stipulate it, it is obvious microwave ovens have those same differences.

Have you ever noticed the wire mesh inside the window? The visible light inside the microwave can pass through that window because the wavelength is small enough to pass through the small holes of the screen. The microwave wavelength on the other hand is so large the screen acts like a solid wall and it cannot pass through. The microwaves just bounce back into the oven chamber.

Now that you know how and why, here are some things to remember. Make sure you never run the unit with the door open. Bypassing the safety switch is a no-no. Never run the unit empty. It must always have a “load” inside to complete its intended function. Never use aluminum foil, gold, or silver edged dishes. Oh, and remember to leave your spoon or fork outside the oven. The metal will spark and could destroy your unit. However, a few types allow foil inside the unit, as long as the foil does not touch any of the six (6) sides. Read the manual that comes with your unit.

To prevent microwave leakage, keep the seal of the door wiped clean and the area where the door seal touches when shut. Buildup of food particles will lift and separate the seal and release the microwave. NEVER slam the door shut. You can damage the seal or weaken the hinges and once again separate the seal from its proper place.

The previous paragraph indicated what to do and what not to do. The next question is, “How do you know if it is leaking?” Well the answer to that question is this; buy a microwave leakage detector. I have to assume the majority of people have no idea there actually exists a device specifically for the homeowner. It is much more affordable than the units we had at the test laboratory where I worked for twenty years. The unit is a MD-2000® Digital Microwave Leakage Detector (See Photo 1). The average cost is between $30 -$40 and you can buy it anywhere on the internet.

Photo 1

If you remember the OHSA limits I addressed earlier, this unit has a wide range of 0 – 9.99 mw/c2. When you use this unit, you put a cup of water on high for about one (1) minute and while the microwave is operating, you hold the unit approximately two (2) inches away from the door seal and check all around the door. This detector indicates the leakage at that distance should be less than 5 mw/c2. Any measurement over that would indicate there is probable leakage. In that case, do the prescribed cleaning I described earlier and try again.

After the cleaning, your second measuring attempt still indicates more than the limit, you have two (2) options. You can still use the microwave, but you may want to start it and step back about 5 feet to get away from it. If you have children, keep them away totally. As adults, we can absorb some, but young children are more susceptible to the radiation. The other choice is, get a new microwave. You may be due for a new one if it too old. If it is practically new, you may want to get it fixed and take it to a qualified technician who can replace the seal and has the capability to re-measure the leakage.

My recommendation is to get one. It comes with simple instructions and all you need is a 9-volt battery. It just may prevent any problems. Most families have smoke detectors, a gas detector, fire extinguishers, and have their house checked for radon. One more safety device is not going to make any difference when it comes to protecting your family.