Frequently, laboratory operations must run continuously or overnight. Equipment and experiments that run unattended during the day or overnight can cause significant problems and harm to personnel, facilities, and equipment. If unattended operations are necessary, it is essential to plan for potential interruptions in utility services such as electricity, water and inert gas. Make sure you perform a hazard analysis to identify potential consequences of failures in utility services or equipment. Design operations to be “fail-safe”, so that one malfunction will not cause a propagation of additional failures.

If necessary, arrange for routine inspection of the operation. If appropriate, leave laboratory lights on during unattended operations, and place a sign on the entrance door. Appendix 3-C is an example sign for unattended operations. You can use this design, or a similar type, to convey critical information to personnel (such as other lab personnel, maintenance, housekeepers, or incident responders) who could encounter your unattended operation. Contact EHS if you have any questions.

A. Frequently Asked Questions about Unattended Operations

Q. What is meant by “unattended operation”?

A: For the purposes of this section, an unattended operation is any unmonitored lab activity that has the potential to release water, gas, chemical substances, electrical energy, or chemical energy during foreseeable failures of equipment or utility services.

Q. Which types of unattended operations would require door signage?

A: Any unattended operation which could potentially harm personnel (such as maintenance workers or housekeepers) due to contact during normal operation or failure; or which could cause substantial damage to property or the environment during failures.

Example: Soxhlet extractor (Figure 3.1)

  • Should stay attended, but would certainly require a door sign if unattended.
  • The hot plate could burn to the touch.
  • In the event of flask breakage, a fire could start if a flammable solvent such as hexane or petroleum ether is in use.
  • A rupture of the condenser water line could flood the lab or rooms below.

Q: What are some examples of “fail-safe” designs?

A: Fail-safe designs help ensure that a failure will leave the experiment unaffected, or convert it to a state that minimizes injury or damage. Examples include:

  • Water flow monitors and solenoid valves that shut off water to a condenser in the event of water line rupture
  • Temperature-sensing monitors that turn off power to hot plates or vessels if the temperature exceeds a pre-set limit for any reason
  • Automatic gas shutoff valves that shut off gas flow in the event of a power outage, leak, or significant seismic event