4
\$\begingroup\$

I frequently need to run long-term tests which have some potential for damage or harm if e.g. someone disturbs the test apparatus without being aware that it's running a test.

Say for example testing an actuator to see how many cycles it can do before failure.

There are two risks I want to avoid:
1) Harming a bystander who is unaware that the apparatus is performing tests.
2) Accidentally leaving the premises when a long-running test is executing, creating e.g. a fire hazard when the test is left unattended.

What are the traditional ways of indicating that a potentially-dangerous apparatus is running and should be disabled at the end of the day?

A red light next to the apparatus might be sufficient to indicate that it's operating, but I think that would not prevent someone from setting up a long-running test over the weekend and potentially causing some event over the weekend.


I want to acknowledge in advance that this question is subjective, but I believe it meets the criteria for a constructive, subjective question in the sense that it's relevant to this community and likely to generate useful, constructive answers.

This question (IMO) is a better fit for Electronics rather than SQA since SQA is specifically for software, whereas electronics may include electronic testing.

\$\endgroup\$

closed as off-topic by Transistor, Finbarr, laptop2d, Anindo Ghosh, Elliot Alderson Jan 7 at 0:47

  • This question does not appear to be about electronics design within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 3
    \$\begingroup\$ Although it may have objective answers, it isn't really electronic design. IMO, the best fit for this question would be the User Experience site (ux.stackexchange). Because it is sepcifically about Human-Computer Interaction, which is totally on-topic there. I'm not voting to close, though. But in case it gets closed here, you may want to try over there. \$\endgroup\$ – dim Jan 2 at 21:25
  • \$\begingroup\$ (This isn't precisely directed at your goals, but suggests something to think about.) I needed to arrange things so that the oven/stove in the home cannot operate at all unless there is evidence of someone present in the room at all times (a short, but adjustable "absence time" is permitted.) I use data fusion and multiple sensors and sensor types to achieve this (e.g., ultrasonic and radar.) \$\endgroup\$ – jonk Jan 2 at 21:26
  • 4
    \$\begingroup\$ I'm voting to close this question as off-topic because it's not an electronics design question but seems to be about signage. \$\endgroup\$ – Transistor Jan 2 at 21:32
  • \$\begingroup\$ Put the running test equipment behind a locked barrier, that if opened, stops the equipment - also have a camera so you can talk to the "idiot" who ignored the "No Entry - do not enter, test running" signs... \$\endgroup\$ – Solar Mike Jan 2 at 21:40
  • \$\begingroup\$ If you can rephrase the question to how do I add safeguards to this design? then it is answerable. Sensor activated shutdown. But what to sense? power, heat , flame CO sensor, sound? motion? current? \$\endgroup\$ – Sunnyskyguy EE75 Jan 2 at 21:57
4
\$\begingroup\$

In the case of laser safety, there are several kinds of safeguards used. These should all either apply or be adaptable to other kinds of hazards:

  • Signage --- laser installations require signs indicating the equipment is dangerous, some classification of how dangerous it is ("class 1", "class 2", etc.), and the appropriate protective equipment required when entering the dangerous area (what type of eyewear is needed, for example)

  • Barriers --- People should be physically be prevented from entering the area except where the signage is present. Doors or gates in the barriers should be locked and only trained and authorized people should have keys to pass through.

  • Interlocks --- The laser should be disabled if the barriers are opened.

  • Education --- Anyone with access to the laser area must be educated on the meaning of the signs, the appropriate protective equipment, etc. People who have access to the area around the laser should be educated on why it's dangerous to enter the actual hazardous area and instructed not to enter.

As for a case where an experiment needs to be shut down at the end of the day, I'd suggest to use a computer control to automatically shut it down, and also you as the person in charge, or some other trained person should be required to check that it actually shut down. (Even better, the human check is done first, and the computer only shuts it down some time later as a back up)

There are two risks I want to avoid: 1) Harming a bystander who is unaware that the apparatus is performing tests.

This should be manageable with the protections I outlined above.

2) Accidentally leaving the premises when a long-running test is executing, creating e.g. a fire hazard when the test is left unattended.

This scenario probably requires an interlock to prevent the equipment operating if the attendant leaves. For example a dead-man switch, or some input needed periodically from the user to keep the equipment operating.

Even better, the equipment should be redesigned to not catch fire.

\$\endgroup\$
  • 1
    \$\begingroup\$ what about a Class III biohazard? j/k \$\endgroup\$ – Sunnyskyguy EE75 Jan 2 at 21:58

Not the answer you're looking for? Browse other questions tagged or ask your own question.