Frequently Asked Questions

Compressed Gas Safety

How far apart should the oxygen and acetylene cylinders be stored?

 Both OSHA and NFPA recommends that oxygen and acetylene cylinders be stored at a minimum distance of 20 feet (6 m) or be separated by a noncombustible barrier of at least 5 feet high.

OSHA 1910.253(b)(4)(iii) – Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease) a minimum distance of 20 feet (6.1m) or by a noncombustible barrier at least 5 feet (1.5m) high having a fire-resistance rating of at least 1/2 hour.

NFPA 51 2-4.3 – Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease) by a minimum distance of 20 ft. (6 m) or by a barrier of noncombustible material at least 5 ft. (1.5 m) high having a fire resistance rating of at least 1/2 hour. The barrier shall interrupt all lines of sight between oxygen and fuel-gas cylinders within 20 ft. of each other.

Food Safety

What is meant by Temperature Danger Zone in Food Safety?

In food safety, the temperature between 5°C and 60°C is known as Temperature Danger Zone. This is because in this temperature zone bacteria can easily grow to unsafe levels. Food handlers should minimize the time that the food spends at these temperatures in order to keep the food safe for human consumption. This should be done by either keeping the food refrigerated at 5°C or below or keeping the food hot at 60°C or more.

temperature danger zone

Rigging, Slinging and Lifting

What is the rule of thumb formula used to calculate the WLL of a flexible steel wire rope?

If the Working Load Limit (WLL) of the flexible wire rope is unknown, the rule of thumb formula to compute the WLL is: Diameter in mm squared x 8 = WLL in kg.


  • The WLL of a 15 mm wire rope = 152 x 8 = 15 x 15 x 8 = 1800 kg
  • The WLL of a 20 mm wire rope = 202 x 8 = 20 x 20 x 8 = 3200 kg.
  • The WLL of a 25 mm wire rope = 252 x 8 = 25 x 25 x 8 = 5000 kg.

What is the rule of thumb for determining the working load limit (WLL) of synthetic rope?

If the WLL of a synthetic fibre rope is unknown, the formula for determining the WLL is: Diameter in mm squared = the WLL in kg.


  • The WLL of a 12 mm fibre rope is: 122 = 12 x 12 = 144 kg.
  • The WLL of a 15 mm fiber rope is: 152 = 15 x 15 = 225 kg.
  • The WLL of a 20 mm fiber rope is: 202 = 20 x 20 = 400 kg.

What are the requirements for safe storage of synthetic webbing slings?

  • Store in a clean, dry and well ventilated place.
  • Never store on the ground or floor.
  • Store out of direct sunlight, ultraviolet light or fluorescent lighting.
  • Store away from chemicals.
  • Store away from oils.
  • Store away from sand/grit.
  • Store away from machinery.
  • Store in a vermin free environment.

When should a synthetic web sling be discarded?

Synthetic webbing slings must be removed from service when any of the following substandard conditions exitst:

  • Label or tag has been removed and/or destroyed or not legible.
  • Knots, snags, holes, tears or cuts.
  • Damage to sleeve.
  • Evidence of external wear or excessive abrasions.
  • Evidence of internal wear.
  • Melting or charring of any part of the sling surface.
  • Any signs of damage by temperatures, sunlight or chemicals.
  • Damage to the eyes, corrosion discoloration or other damage to end fittings or terminal attachments.
  • Signs of contact with acids for nylon slings or signs of contact with organic solvents for polyster slings.
  • Broken or worn stitches. 

When should lifting hooks be discarded and removed from service?

Lifting hooks must be discarded and removed from service if any of the following unsafe conditions are observed during the regular and pre-use inspection:

  • Missing or illegible manufacturer identification.
  • Any cracks, nicks and gouges.
  • Damage from heat.
  • Any unauthorized repair done on the hook.
  • Any twist from the plane of the unbent hook.
  • Improper operation and locking of self-locking hook.
  • Any wear exceeding 10% of the original dimension.
  • An increase of the throat opening by 5% due to wear or distortion.

When should shackles be discarded and removed from service?

Shackles must be discarded and removed from service immediately if the following unsafe conditions are observed during regular or pre-use inspection:

  • Excessive pitting or corrosion.
  • A 10% or more reduction from the original dimension at any point around the body or pin.
  • Damage on the shackle body including: bent, twisted, distorted, stretched, elongated, cracked, or broken load-bearing
  • Excessive nicks or gouges.
  • Indication of heat damage (weld splatter, arc strike, etc.)
  • Incomplete pin engagement.
  • Excessive thread damage.
  • Evidence of unathorized repair or welding.

The Golden Rule of Lifting

Lifts utilizing cranes, hoists, or other mechanical lifting devices will not commence unless:

    • An assessment of the lift has been completed and the lift method and equipment have been determined by ancompetent person(s);
    • Operators of powered lifting devices are trained and certified for that equipment;
    • Rigging of the load is carried out by a competent person(s);
    • Lifting devices and equipment have been certified for use within the last 12 months (at a minimum);
    • Load does not exceed dynamic and/or static capacities of the lifting equipment;
    • Any safety devices installed on lifting equipment are operational.;
    • All lifting devices and equipment have been visually examined before each lift by a competent person(s).

    Fibre Rope Inspection

    During fibre rope inspection, condemn the fibre rope from safe use for lifting purposes if any of the following is observed during inspection:

    • Strands are fraying
    • Strands are cut
    • Rope rotted by acid or alkali
    • Rope affected by heat or sun
    • Rope affected by molds
    • Rope has been overloaded
    • Rope chafed inside or outside
    • Unlaid stands
    • Knotted rope

    Road and Driving Safety

    What does a solid white center or separation line on the road indicate?

    No lane changes allowed.  Solid white lines are typically used in road construction areas.  Passing or changing lanes here can be unsafe and dangerous. Other additional markings include:

    • Double solid yellow center lines mean no passing is allowed in either direction.
    • A single dashed yellow center line means you are allowed to pass if the road ahead is clear.
    • A combination of solid and dashed yellow center lines has two meanings: If the dashed line is in your lane, you can pass. If the solid line is in your lane, you can't pass.

    Whose responsibility is it to ensure traffic merges efficiently?

    Typically the merge sign is designated for the driver who is entering a dedicated roadway or expressway.  The driver merging has the responsibility to ensure he/she enters the expressway at a safe speed that does not cause undue hazards to the other motorists.  The merging driver should avoid sudden slow downs or stops and make sure there is ample merge space between other vehicles.  Merge at the end of an on-ramp. Trying to cut in early from the middle of the on-ramp can surprise other drivers and cause an accident. Although some drivers will move to the left lane to allow cars to merge, this is a courtesy and not a requirement.

    Does traffic on all lanes required to stop if a school bus stops and has its red flashers activated?

    School bus red lights and stop arm are intended to control only two lanes of traffic. Only traffic directly behind the school bus and traffic in the lane closest (typically the left lane) to the school bus must stop. Oncoming traffic must also stop.  You are not allowed to pass a school bus while lights are flashing red and the STOP sign is extended.

    Is it okay to drive on the shoulder to get around traffic if you are turning right?

    Shoulders are for emergency use only and serve as a buffer.  Don't use a highway shoulder as a travel lane or to back up to a missed ramp.

    Are bicyclists allowed to ride on vehicle roadways and highways?

    Bicyclists may ride on authorized streets and highways but must generally comply with the rules of the road that vehicle drivers must obey.  Bicyclists are not allowed to ride on interstate highways or where otherwise prohibited.  Check with your local police department for bicycle laws. 

    Electrical Safety

    What does the third prong on a 3-prong plug do?

    The third prong provides a path to ground for electricity that may “leak” from an appliance or product.