MRA modifies our base ovens to add the following options to enhance the performance of the standard laboratory microwave oven. The options below are the most desired through the years that MRA has been providing laboratory and light batch processing microwave ovens. Other options are available – please consult MRA.

Process chamber venting:
This option increases the process chamber venting and includes an exhaust vent port suitable for connection to standard exhaust hoods. Airflow is greater than 17 cubic feet per minute.

Temperature controlled processing:
Place the thermocouple in/on the sample being heated and the temperature controller will maintain the temperature of the sample per the easy user-programmed cycle. The temperature controller times all ramp rates and soak at temperatures. Once programmed, simply start the cycle and walk away. At the end of the cycle, the microwave oven will give a visual and / or audio signal. Thermocouples are replaceable and can be ordered with an operating temperature range up to 1,600C for a wide variety of process options.

True power variation:
Most microwave ovens are able to adjust the power delivered to the sample, however, the method that they adjust their power often damages small sized or samples that are fragile. Most microwave ovens adjust their power by cycling full power on and off.

This can best be demonstrated by the following example; a sample that needs 500 watts of microwave energy for 10 minutes is heated in a 1,000-watt microwave oven. Most microwave ovens are designed to provide average power. The cycle begins by the oven turning on at full power, 1,000-watts for 3-5 seconds. The microwave power is then turned off for 3-5 seconds. This continues for the entire 10 minutes. The average power is 500 watts. This may be fine for large bulk samples/product to be heated.

Let's look at a small or fragile sample. The sample is very small, 10 ml of a solution to be heated. We want 250 watts of heating for 5 seconds. With most microwave ovens this cycle could not be achieved, because the microwave power will come on at 1,000-watts for 3-5 seconds. The sample will become significantly overheated if not destroyed. MRA has developed a method to truly adjust the power level. The power is set by a dial or controlled by the temperature controller (if equipped). The actual average power is changed. If the desired power is set for 250 watts, the output power of the oven is 250 watts. The output power remains at 250 watts for the entire heating time. Precise power setting and accurate timing all but eliminates sample damage.

Corrosion resistant coating:
Although the cavity is stainless steel, it is still susceptible to corrosion when continuously exposed to corrosive environments. The electronics are also susceptible to corrosion when in those environments. This option protects the cavity, door (critical to protect from microwave leakage) and the electronics. Life is extended 2-3 times when the microwave oven has this corrosion resistant coating and is used in corrosive environments. As each environment is different, please contact MRA to discuss your environment and to determine if this is the appropriate option for your application.

Other options:
Other options available upon request. We believe we offer microwave ovens with features that are most desirable for laboratory and industrial batch processing at outstanding value to our customers. Microwave Research Application Inc. would be pleased to discuss with you how microwave processing can be used to achieve your unique requirements. Please do not hesitate to contact us.