Fluid Power Safety
1. Personal Safety
- All employees of the Mechanical Engineering Department must complete general safety training.
- New students must receive an orientation on lab operating procedures before working in a lab.
- Food is forbidden in the fluid power labs.
- OSHA-approved safety glasses with side shields are absolutely required when working around fluid power equipment.
- Wear a face shield when disconnecting or connecting hoses or pipes.
- Oil leaks can occur without warning. Ensure that your eyes are adequately protected.
- Ensure that an eye wash station is available in your lab.
- Students are required to watch "Eye Safety" video (available in the Student Shop).
- Always remove rings, watches and jewelry before working with fluid power equipment.
- Fluid power equipment can generate very high forces and torques. Be aware of crushing hazards!
- Hydraulic fluids can become HOT! Be aware of burn hazards.
- Be sure that a system is depressurized before working on hoses or pipes. For extra protection against injection accidents, wear appropriate gloves when loosening hoses or pipes.
- Do not wear gloves when working around moving machine parts which could catch them.
- Students are required to watch "High-Impact Hand Safety" video (available in the Student Shop).
- Do not wear ties or other loose pieces of clothing that can get caught in moving equipment.
- Open footwear is forbidden in the labs. If appropriate, wear safety shoes.
2. Lab Safety
- Never work in a fluid power lab alone.
- Know where the emergency shut-offs are located and how to operate them.
- Correct or report any hazardous conditions (electrical, trip hazards, etc.).
- Maintain clear egress pathways at least 24 inches wide at all times.
- Clean up spilled oil immediately and dispose of the clean-up materials appropriately.
- Put away your tools and materials at the end of your work session. Keep the lab tidy.
3. Equipment Safety
- Students shall publish a safety checklist for equipment for which they are responsible.
- Students must read the safety checklist for each piece of equipment before operating it.
- Ensure you know the location of the emergency stop button before starting equipment.
- Always depressurize accumulators or pneumatic reservoirs before working on fluid power apparatus.
- If an oil spray could occur, ensure that the sprayed oil can not cause a fire or explosion due to exposure to an ignition source.
- Check the application pressure, system pressure, and component pressure before connecting a system to a pump or pressure source. The maximum operating pressures are listed on equipment labels or published on manufacturer websites.
- Check the pressure ratings of all hoses and tubes included in your system. Never include "SAE 100R4" hose in pressure lines. If equipment contains hoses, ensure they are adequately constrained to prevent a whipping hazard in the case of a failure.
- Use the correct connectors and adapters when connecting hoses, tubes, peripherals, and actuators. Hydraulic connections use one of four standards:
- ORS: Face O-Ring
- ORB: SAE O-Ring Boss
- SAE Flare 37 deg (JIC)
- SAE Flare 45 deg (rarely used)
Never mix connector types.
- If quick couplings are used, check the compatibility of the female and male sets marked on the parts. The part numbers and markings are listed on manufacturers' web pages. For example, an AERO Quip coupling -8 set uses a 5610-8-10S male connector and an FD56-4101-08-10 female connector.
- When assembling quick connect couplings, ensure that you hear the couplings snap together. Ensure that the couplings are engaged by gently trying to pull them apart. If in doubt, disconnect and re-connect the couplings.
- Periodically check hoses for leakage, cracks, kinks, or breaks.
- Identify likely trajectories for parts that could become airborne in a failure (such as fragments launched by a failure of a rotating shaft) and stand clear of them.
- Test your equipment for leaks at low pressure before raising the pressure to the operating pressure.
- If using the shop oil supply, learn to operate the power unit by reading the separate laminated instruction sheet. Make sure to turn on the cooling water for the power unit before turning on the power unit itself. Turn off the power unit and the cooling water before leaving the lab.
- If your equipment contains a large manifold, bleed the air out of it before pressurizing it for the first time. (Otherwise, it stores energy like an accumulator in the compressed air.)
4. Chemical Safety
- Departmental chemical safety training is required for all lab personnel. MSDS sheets shall be maintained for all chemicals used in a lab. Familiarize yourself with the MSDS sheets relevant to your work.
- Properly label all chemicals, including new and used hydraulic oil.
- Store flammable chemicals and oils in appropriate designated places with clear labels.
- Spilled and other dirty oil (oil that cannot be filtered and re-used) should be stored in a container labeled "Hydraulic Oil Waste."
- Every container used for chemical waste must be clearly labeled "Hazardous Waste" using labels available from the University of Minnesota's Department of Environmental Health and Safety (DEHS). The waste shall be identified with a DDC #, a CAS #, and, if applicable, an EPA # that can be looked up on the DEHS web site. (For example, "water, oil, and floor dry" is DDC #05NH, CAS #UOFM22A, and no EPA #).
- A Hazardous Waste Packing Form must be filled out to accompany any hazardous waste. Contact a departmental safety officer to find out where to drop off the waste material for collection.
- "Oil Dry" and other materials soaked in oil shall be double-bagged. (Alternately, DEHS can supply a seven-gallon pail with a screw-on lid.) The bags or pails shall be labeled with the appropriate hazardous waste label (DDC #05NH, CAS#UOFM22A, no EPA #). Contact a departmental safety officer to find out where to drop off the bags or pails for collection.
- Soiled cloths shall be deposited in the red receptacles in the lab for washing and re-using.
5. Design Safety
New equipment must be designed to conform to ISO 4413 (Hydraulics) or ISO 4414 (pneumatics)
Examples (paraphrased; designers must comply to the actual wording of the standard):
- Design for fail-safe operation, considering all possible modes of failure.
- All components shall operate within manufacturer's specifications.
- All parts of the system shall be protected against over-pressure.
- Equipment shall incorporate an emergency stop or emergency return control, whichever provides maximum safety.
- Emergency stops shall be readily accessible under all conditions of working and shall operate immediately.
- Emergency stops shall not require that any actuator be energized.
- Hydraulic circuits incorporating accumulators shall automatically vent the accumulator liquid pressure or positively isolate the accumulator when equipment is shut off.
- If an accumulator is not automatically vented, complete information for safe servicing shall be given on or near the accumulator in a visible location, and duplicate information shall be provided on the circuit diagram.
- Equipment shall be designed so that loss of electrical, pneumatic and/or hydraulic power shall not cause a hazard.
- Neither surge pressure nor loss of pressure shall cause hazards.
- Pump inlet temperatures should not exceed 60 deg C when maximum ambient temperatures exist.
- Rotating parts shall be guarded to provide adequate protection against hazard.
- Flexible hoses shall only be used where necessary. Their length shall be minimized and they shall be protected from abrasion. If failure causes a hazard, the hose shall be restrained or shielded.
- Piping shall not be used for equipment support.