2.80.10 Microwave Oven Safety – Policies and Procedures Library – The University of Queensland, Australia

1. Purpose and Objectives

This road map provides aid to researchers who are planning to use or are using domestic microwave ovens in laboratories .

2. Definitions, Terms, Acronyms

RF – Radiofrequency radiation
EME – electromagnetic Energy
GHz – Giga Hertz

Microwave – Radiofrequency radiation nominated as microwaves are in the compass 0.3-300 GHz. Microwave ovens use a specific frequency being 2.45 GHz .

3. Guidelines Scope/Coverage

This guidepost covers the use of domestic microwave ovens for general testing ground use and their effects on human health. It does not cover specialised or improper microwave use .

4. Guidelines Statement

Where domestic microwave ovens are being used in lab or research settings, persons must be aware that they may be changing the intended use as stipulated by the manufacturer. It is consequently authoritative to risk assess the work involving the use of domestic microwave ovens in a lab or inquiry place, and where allow incite base hit and command measures. regular maintenance of the microwave ovens should be considered. domestic microwaves should not be modified for research purposes .

5. Hazards

All microwave ovens have at least two base hit mesh switches which stop the generation of microwaves immediately if the door is opened. The plan of modern microwave ovens are such that the microwaves should be contained within the oven, but it is inactive possible for some escape to occur around the doors of certain microwave ovens. generally, the command design of oven doors should restrict this escape to a charge well below that recommended by the Australian/New Zealand Standard AS/NZS 60335.2.25:2011 Household and like electrical appliances ‑ Safety Part 2.25 : particular requirements Microwave ovens for microwave ovens including combination microwave ovens. The Standard specifies a test to assess the charge of microwave escape and states that ‘The microwave escape at any point 50 millimetres or more from the external open of the appliance shall not exceed 50 watt per square meter. This standard applies to ovens designed for domestic applications, even if used in a workplace. The recommend limit is conservative and includes meaning safety factors, so that tied escape levels appreciably above the specify will have no known effect on human health.

6. Controlling the Risks

To minimize the risks associated with microwave ovens, users must adopt the follow rules :

  • Never attempt to heat flammable liquids or solids, hazardous substances or radioactive materials in any type of microwave oven, whether domestic or laboratory-grade.
  • Never attempt to defeat the interlock switches that prevent a microwave oven from operating with the door open.
  • Users should always ensure that the oven cavity is adequately ventilated. To help ensure this, the unit should be operated only on a clear open bench and not in a location where the vents could be obstructed by books or equipment.
  • Do not place any wires, cables, tubing etc. between the door and the seal.
  • While there is no requirement for recurrent testing for microwave leakage, regular visual inspections are recommended to check for the following:

    • The sealing surfaces are clean and do not show any sign of damage;
    • The door closes cleanly and there is no distortion of the frame;
    • The window panel is not damaged;
    • The door is not damaged in any way.

If there is any attest of this type of price the unit of measurement should be taken out of service and referred to the authorized servicing agent .

  • Do not attempt unauthorised repairs or modifications to the mechanical or electrical systems of a microwave oven. Where a unit is suspected to be faulty it should be disconnected from the power supply, removed from service and labelled with an appropriate tag while awaiting repair or disposal.
  • Any irreparable or redundant microwave oven should be unplugged from the GPO, and rendered inoperable by removing the power cord or cutting off the plug before disposal.
  • Never use a microwave oven in a laboratory for food preparation (or vice versa).
  • Do not heat sealed containers in a microwave oven. Even a loosened cap or lid poses a significant risk since microwave ovens can heat material so quickly that the lid can seat upward against the threads and containers can explode either in the oven or shortly after removal.
  • No metal objects of any kind should be placed in a microwave oven. This includes aluminium foil and plastic coated magnetic stirrer bars.
  • Users need to take care to avoid overheating liquids (super-heat) in a microwave oven. It is possible to raise water to a temperature greater than the normal boiling point; when this occurs, any disturbance to the liquid can trigger violent boiling that could result in severe burns.
  • Microwave ovens must be electrically grounded and connected using a properly rated three pin cord and plug. Microwave ovens should be inspected by a competent person to ensure compliance with this requirement before going into service and if not connected to a safety switch protected circuit, they need to be tested and tagged at appropriate intervals.
  • Defects in equipment or difficulties in operation with a microwave oven should be reported promptly to the laboratory manager or supervisor.
  • Laboratory users who have cardiac pacemaker implants are not likely to be susceptible to interference where leakage levels are within the recommended limits. Persons with pacemakers should obtain and rely on their own medical advice in this respect.
  • Proper heat resistant gloves should be worn when handling items that come out of a microwave oven. Laboratory gloves such as latex or nitrile gloves do not offer protection if heated liquid is spilled on you.

7. Specialised Microwave Usage

The use of microwave heat as a reaction accelerator in the chemical inquiry plain is to be treated with caution. While techniques have been developed, these involve the consumption of specialized laboratory-grade equipment rather than domestic ovens. Should a want be identified for this application of microwave heat, the research worker ( s ) should consider purchase or gain access to such specialised microwave ovens.

application of microwave inflame to industrial processes in, for exercise, the chemical engineering field, will require detail risk assessment in the plan phase .

8. Contact for Additional Information

Contact your local Radiation Safety Officer, or
HSW Division Radiation Protection Advisor HSW @ uq.edu.au