The information signs and Protective Personal Equipment (further PPE) are crucial parts to be used for lowering of hazards and reduce risk in working areas. This research will analyze some informative and protective facilities available to defend employees from mechanical and vibration hazards and offer a few new safety signs. All images for this paper were taken from the websites of companies selling safety signs or PPE and therefore sources not cited.
Safety signs are an imperative way of protecting employees from accidents. The target is to convey information in a comprehensive way about objects and situations that can be dangerous. In case of use heavy vibrating machinery, for instance, well placed signs can help to avoid unnecessary exposition to vibration sources and prevent accidents caused by moving parts of equipment. Most of the countries have regulations regarding standards of design and use of safety signs. All official documents are regulating requirements and rules applied to implementation and use of safety signs.
There are three main signs categories (Safety Signs and Colour at Work, 2007):
- Regulatory, represented by a circle indicating that an order is in force.
- Warning, in a shape of a triangle indicating caution or danger.
- Information, having square or rectangular shape and providing safety related information.
In addition to the shape all safety signs are sub-divided into the groups which are defined by different colors for each sub-category within every main category. There are different color scheme for prohibition and mandatory signs in the regulatory category, caution and danger in warning division, emergency and general information within an information group.
Personal Protective Equipment
Another way to control hazards in working areas is the use of Personal Protective Equipment (further PPE). PPE is the last barrier to gain the control over hazards in the working areas. PPE appears at the last position in the controls list just to show, that prior to the use of PPE all other methods of hazard controls are to be used to eliminate or minimize risks to an acceptable level. The definition of PPE should be understood as an equipment worn by the worker to protect from hazards. Different kinds of PPE are available depending on the work cite. Some types of PPE belong to the group of very sophisticated equipment. According to the law and regulations in most of the countries, the employer must provide PPE of the correct type for the task performed. Equipment should be supplied and maintained in good condition. The employer must ensure that PPE is used as prescribed. The workers duty is to use protective equipment as prescribed.
All safety signs must be posted in such locations where they are clearly visible, free from any obstructions and at the sight line of the worker. Signs, related to the particular rooms and areas should be posted at the entrance. Safety signs related to the conditions of use for specific machinery are to be posted in the storage areas of such equipment.
Regulatory signs related to mechanical hazards and vibration. Regulatory signs are divided into two sub categories, prohibition signs and mandatory signs. Prohibition signs have red and black images on the white background. They forbid some particular action in the area where signs are posted. Mandatory signs have white images on the blue background. This type of signs requires predefined action to be performed. In the most cases mandatory signs dictate the use of one or several types of particular PPE or use of safety related devices on machinery. Some sample signs are shown in tables 1 and 2 for prohibition and mandatory signs correspondingly
Use of forklift prohibited. To be located in areas where use of the forklift id not possible due to construction reasons like weak flooring or where use of forklifts is unsafe due to safety reasons
No bulldozer sign. This prohibition sign is similar to the sign above but denies use of bulldozer and has wave images highlighting hazards from bulldozer as a vibration source.
No drilling. For use in areas where drilling may accidentally damage hidden pipes or cables. Also, drills create vibration while operating and this sign might be used with general vibration warning sign.
Do not oil or grease running equipment. This sign designed to post on or around running machinery with open gears to prevent accidents caused by potential mechanical hazards.
No wrenches or spanners. This sign has at least two potential ways to use. First one to prevent maintenance works on equipment in operation and the second to prohibit disassembly of devices by unauthorized persons. In both cases the use of this sign will reduce mechanical hazards.
Safety helmet mandatory sign. Used in areas where head protection required. In some places like passages in industrial areas only helmet required for visitors.
Gloves are mandatory. The sign for use in areas where gloves are needed to protect from mechanical hazards. May have additional text sign pointing on the obligatory use of anti-vibration gloves as picture on the right is showing.
Air supplying hood. Posted at the entrance to spaces where air is non-breathable. Not directly related to mechanical hazards and demonstrated here as a sample of safety sign which meaning not obvious and may be misunderstood.
Lifting guard required. The sign is for machinery and power tools where guards should be lowered with running equipment to protect from mechanical hazards.
Guard required. Used for equipment with open moving parts which should have permanent guard installed to protect from mechanical hazards.
Warning signs related to mechanical hazards and vibration. Warning signs have triangular shape with black image on the yellow background, and indicating caution or danger. Another type of warning signs indicates a definite hazard and has white image on the red background (Safety Signs and Colour at Work, 2007). This type with such colors and shape combination is standardized in Canada by CAN/CSA Z321-96 but is not used in other countries. Most of the countries are using black on yellow triangular signs for the same hazards. Therefore, sample images were taken from Canadian sources and are not directly related to mechanical hazards. Tables 3 and 4 below are showing some examples of warning signs related to the mechanical engineering.
Rotating cutting hazard. The sign designed to be posted nearby power tools and machinery which have rotating cutting tools such as circular saw or milling machine.
Running machinery warning. To be posted in areas where mechanical hazard is caused by the risk of hands trapped into open gears and other rotating or moving parts of machine
Falling objects. The sign to be used at the entrance to the area where some works performed at higher level and tools or other heavy objects may fall and cause accidents. The sign provided has slightly too small pictographs which could be hard to read from the distance. The suggestion is to have images better readable.
Excavator warning sign. Designed to post in areas where excavation works performed to warn about mechanical and vibration hazards from operating machinery.
The sign to be posted in areas where operating machineries such as forging press and similar are the source of mechanical hazard
Danger warning signs
Corrosive liquid. The sign is for use in the areas or on the tanks containing chemicals which may cause scin burn or irritation.
Electrical hazard. The sign is used on the doors of electrical control cabinets and other areas where dangerous voltage present.
Explosive. The sign is to be used in areas where explosion risk exists due to presence of specific materials, vapors or dust which may lead to explosion.
Flammable. This sign is used on spaces and containers which hold flammable materials.
Pressurized gas sign. The sign is designed for use at the entrance where gas bottles are located or stored.
Signs used for information related to the safety and actions or behavior in emergency situations have white image on the green background. Safety signs of this group are often supplemented with arrow signs in same colors to ease safety related directions or locations. General information signs indicate permission or public information and have white image on the blue background. These types of the signs show locations of service and recreation facilities and are not directly linked to the work activities. As it seen, most of them are designed for general use but can be used as well in industry to show location of some services such as parking or dining areas, bus stops, refueling stations and others. Sample information signs are demonstrated in the tables 5 and 6.
Information safety signs
First aid kit. Not directly related to mechanical hazards but first aid kits must be located in areas with mechanical hazards and accompanied with this sign.
Emergency eye wash. Same as the sign above, not directly related to mechanical hazards but emergency eye wash should present in the areas with mechanical hazards and supplied with this sign.
Grinder sign. Supposed to point to the location of the bench grinder. Should have warning signs about vibration hazard and mandatory signs to use lifting guard and proper PPE posted in the same place.
Escape route. To show the route to safely leave hazardous areas in case of emergency.
Emergency stop button. The sign to be located near emergency stop for easy location in case of machinery malfunction.
General information signs
Dining area. General information sign not related to hazards as all signs of this category. Used in industrial areas to specify location of the places where meal can be taken.
Parking area. The sign indicates area where parking is allowed and safe. The presence of this sign suggests the area safe from mechanical and vibration hazards.
Hospital. To be posted at the hospital entrance and on the route with associated pointers.
Information sign. It is not related directly to hazards but might be located in places where additional information regarding possible risks and hazards could be obtained.
Direction sign. Showing the safe direction to walk or drive. If this sign is not accompanied with warning signs the route supposed to be free of hazards
New Design Signs
New signs were designed as a part of this work for each category. These signs are presented in table 7 with descriptions.
The prohibition sign is restricting the use of vibrating tools. Jackhammer used as the tool image as it is most and widely known as vibration source.
General sign warns about vibration risk in the area. Vibrating had an image used as the symbol warning about hand and arm vibration. However, the sign could be used in the areas with any vibration hazard as it has exclamation mark and text information about hazard.
The sign supposed to show safe passage in the areas where machinery having moving parts and creating vibration are operated.
Personal Protective Equipment (PPE)
PPE should be worn even if all engineering controls were applied and all possible risks minimized. Hazards might remain in the working area. Therefore, use of PPE is obligatory on the most of workspaces and especially with mechanical hazards and vibration present in the area. There are moving machines and rotating equipment, suspended loads, risks of flying particles, possibility of harmful gases and vapors inhalation during equipment maintenance, multiple sources of noise and vibration. It is obvious that PPE is needed in such environments. Due to its importance, the use of PPE is regulated by law in the most of the countries. PPE should be used as a last resort. Wherever there are risks to health and safety that cannot be adequately controlled in other ways, regulations require PPE to be supplied (PPE at work, 2013, p.1). Table 8 contains examples of most important PPE types which are designed to protect from general mechanical hazards in routine working and normal weather conditions without handling dangerous materials. Special PPE is available for specific tasks, i.e. working with aggressive chemicals, welding, working aloft and others. Anti-vibration PPE is one of the specific types. At the moment only gloves are produced and approved for the protection from the vibration. And even approved anti-vibration gloves, according to tests (Hewett, 2010, p.17) have no or even negative effect in certain conditions and with use of some tools on some materials.
Coveralls. While it is not strictly regulated, coveralls must have preferably bright colors such as orange or red for high visibility. The good quality coveralls must be made from natural fabrics with flame retardant impregnation and have stripes of light reflecting ribbon to improve workers visibility in dark times of the day.
The safety helmet must serve its main purpose to protect from injuries caused by falling object or hit some obstructions such as low beams. Therefore, all types of safety helmets should be tested and approved. Protective helmets must be equipped with cushion device, size adjustment device and chin strap to secure helmet on the head in windy weather conditions.
Safety eye-wear. Various types of safety eye-wear are available. General purpose glasses and goggles, UV protection glasses, gas welding glasses and even face masks are kind of eye protection. Despite on wide selection, general requirements for eyes protective devices should be the same. These devices should protect not only front but sides as well, are to be made from non-breakable material and have to be clear and not restrict human vision.
Safety footwear. The right choice should be made when selecting correct type of safety boots. This type of footwear has different designs and properties depending on application and area of use. However, all of them must have non-slippery sole and toe protection.
Hand protection. This type of PPE has probably the widest number of options and types to choose from. Therefore, selection of correct type is important but requires some knowledge to get the right type for the task. Anti-vibration gloves are shown on the provided image.
Existing safety signs are mostly of general type. They are designed in such a way that it is possible to use them widely in any area of human activity. There is one major and the most important reason for that. Any person, even new and absolutely not familiar with the environment should recognize and identify all essential safety signs. However, if any specific signs required in some kind of industry, they should be designed according to standards and supplied with text explanations. Not all safety signs found for the analysis in this work are easy to read or understand. Some of them have small details which are hardly readable from a distance while other have quite specific pictographs which might not be easy to understand even by people involved in the task. During this research three prototype safety signs were designed and created to help minimize an effect of vibration.
Regarding PPE, conclusion is that the right choice of the correct Personal Protective Equipment is crucial. PPE is the last barrier to prevent accidents and improperly selected PPE may not improve but worsen the protection level and lead to personal injuries. Hence, PPE must not be just worn but should be of the correct type for the task and decent quality. For example, anti-vibration gloves are the only type of vibration protection PPE available, and such gloves not always help to reduce vibration effect but even increase the risk of vibration related professional diseases. Therefore, the best way to minimize negative factors from vibration is to plan works in such a way that minimizes exposition and use better quality equipment with a lower level and less harmful frequencies. PPE designed for protection from mechanical hazards undoubtedly must be made from decent quality material and properly designed to protect workers and not restrict movements or create obstructions or limitations to ability in task performance.