Posts Tagged ‘chain saw safety’
Personal Protective Equipment – (PPE) has to be an integral part of our everyday workplace safety plan. Here is a review of some important facts about personal protective equipment while operating a chainsaw.
Most of us have probably been told – or at the very least heard about – the necessity of wearing proper personal protective equipment when we use our chainsaws. It gives us that last line of defense in preventing injury, or at the very least, reducing the severity of them. The most important items of ppe include a hard hat, hearing and eye protection, leg protection, and foot protection. Other types of protection out there include cut resistant gloves, and upper body protection provided by shirts and/or jackets that contain cut resistant materials.
However, knowing what to wear is only half of the formula. Knowing when to replace it is equally important. Wearing defective or outdated equipment gives a false sense of security – not to mention inadequate protection when we need it.
So here are some facts that need to be considered when analyzing the ppe we bring to the job every day.
- Hard hat– most manufacturers recommend replacement of hard hats after 5 years after the date of manufacture. Other factors that reduce the life expectancy of helmets include exposure to ultra-violet rays, marking on them with magic markers, placing stickers on them that are not approved to be placed on plastic (that would include almost every sticker available), dropping them on hard surfaces, cleaning with harsh chemicals, or drilling holes in them for ventilation. There is also a disclaimer that comes with each helmet that should be read to be sure all information available is covered.
- Hearing protection – ear muffs need to be maintained by removing the protective liners inside the muff and cleaning it occasionally. Also, the seal around the outside usually gets damaged in cold weather, so they should be replaced when damaged. Ear plugs also need to be replaced on a regular basis. Sponge type plugs should be replaced daily.
- Eye protection – be sure that eye protection is in tact, not broken, visibility is good, and is adequate for your particular needs. ( Remember, if eye glasses or goggles are worn, they must include safety lenses and provide peripheral protection.)
- Leg protection – leg protection needs to meet certain criteria in order to provide adequate protection. It is required that the equivalent of 4 layers of protection be used, and 6 layers of protection is recommended. Those layers must stay intact to provide maximum protection, so any time the inside layers of the protection are cut, the chaps or pants must be replaced. Patching them is not an option. They must also fit properly, so the protective layers must extend from the top of the thigh to the top of the work boot. We recommend they extend slightly over the top of the work boot for maximum protection. And they must be kept clean – so wash them according to the manufacturers recommendations, which are usually attached to the garment.
- Foot protection – work boots with cut resistant material and steel toes are recommended to protect our feet from chain saw cuts, and heavy objects pinching our toes. How many times has it happened that logs roll after they’ve been cut and our feet somehow get in their way?
None of us want to get injured while on the job, and there are generally two ways to reduce that possibility – good technique, and good ppe. Proper training along with purchasing and maintaining good ppe will certainly keep us safer!!
So let’s describe the different types of notches, and the advantages and disadvantages of each. There are three types of notches commonly used in the logging industry by chainsaw operators in tree felling:
1. Conventional notch (35 degrees plus or minus open )
Advantages:
* Most commonly used and recognized
* Almost everyone has seen it and knows how to cut it.
Disadvantages:
* Easy to bypass the cuts
* Opening is not wide enough – allowing the two face cuts to contact one another prior to the tree hitting the ground, allowing stump pull, side scarring, or worst case scenario – barber chairing.
* Much easier to cut the hinge off, since the back cut must be made above the notch cut, making judgement of the thickness of the hinge difficult.
2. Humbolt Notch (45 degree open)
Advantage(s)
* Allows the butt log to be cut without the notch cut being taken out of the log, allowing the butt log to be cut evenly and maintaining the full circumference of the log
Disadvantage(s)
* Infrequently used, especially in the Midwest, so it is not easily recognized.
* Difficult to match the two notch cuts because of the method required to cut it.
* Cannot cut the stumps as low as the other techniques because the angled cut needs to be taken out of the stump.
* The opening is not wide enough, allowing the two face cuts to contact one another prior to the tree hitting the ground, allowing stump pull, side scarring, or worst case scenario – barber chairing.
3. Open Face Notch (70 degrees or more)
Advantages:
* Much easier to match the two notch cuts, allowing the notch to work during the entire travel of the tree to the ground
* Allows the tree to fall almost completely to the ground before the two notch cuts make contact, reducing the possibility of stump pull, side scarring, or barber chairing.
* Because the bore cut is recommended in combination with the open face notch, setting the hinge width and thickness is made much easier, allowing for directional felling, and allowing the tree and stump to hold together longer, giving the feller more time to retreat into his/her escape route before the tree releases.
Disadvantages:
* Relatively new process, so not fully understood or recognized as effective.
When cutting notches, regardless of the type used, the following are some requirements in order for them to work properly.
If using the conventional or Humboldt notches, the opening must be a minimum of 45 degrees. The depth of the notch cut should be approximately 1/3rd the diameter of the tree’s DBH (diameter – breast height) The minimum width of the notch should be a minimum of 80% of the trees’ DBH. The two notch cuts MUST match at the back of the notch –bypassing one cut with the other allows the bypass to create a fulcrum which can cause stump pull, side scarring, or barber chairing.
If using the open face notch, the opening must be a minimum of 70 degrees – and 90 degrees is optimum. The depth of the notch is achieved when the width of the notch cut reaches 80 % of the diameter of the trees’ DBH. If the tree has side lean that must be controlled, a deeper notch to achieve a longer hinge is recommended. Again, the two notch cuts must match in order for the notch to work properly.
All of the notches above are acceptable and will work if cut properly. No matter which notch you choose, if it isn’t cut right, will not work right. And the other element that makes them work properly is the type of back cut used with each one. It is essential that hinge wood is left no matter which notch is used, . It has been our experience and it has been shown that the open face notch in combination with the boring technique will allow the sawyer to have better control of the tree, increase the value of the tree, and be safer in his everyday activities.