PERSONAL PROTECTIVE SYSTEMS AGAINST FALLS FROM A HEIGHT

 

Personal protective systems against falls from a height protect the user against falls from a height by preventing or arresting falls. In particular:
• Fall arrest is the action which prevents the user from hitting the ground, a structure or other obstacles during a fall.
• Fall prevention is the action which stops the user from approaching an area where there is a risk of falling.
• Work positioning is the action which allows the operator to work tensioned or suspended in a way that avoids falls.
A personal protective system against falls consists of an assemblage of components which are either permanently connected to each other or can be separated. It is comprised of: body harness, secure anchorage point and connection system.

FALL ARREST SYSTEM

A system that arrests falls and limits the impact force on the body of the user during fall arrest. The main characteristics of a generic fall arrest system are as follows:
• the system limits the length of the fall but does not prevent it;
• the system allows the user to access areas or positions where there is a risk of falling, but if a fall occurs it is arrested immediately;
• the system leaves the user suspended after an arrested fall.
A fall arrest system must be assembled in such a way as to prevent the user from hitting the ground, a structure or any other obstacle. The minimum required distance beneath the user’s feet must be determined; see the manufacturer’s instructions. In a fall arrest system, the body harness is the only device suitable for holding the body.
A fall arrest system must include energy absorption elements or functions to ensure that impact forces on the user’s body are limited to a maximum of 6 kN.
In particular, a fall arrest system includes: body harness, secure anchorage point and connection system.

 

 

A - BODY HARNESS
B - SECURE ANCHORAGE POINT
C - CONNECTION SYSTEM

 

 

RESTRAINT SYSTEM

A system which prevents falls from a height by limiting the user’s movement. The main characteristics of a generic restraint system are as follows:
• the system limits the user’s movement so that they cannot reach areas where there is a risk of falling from a height;
• the system is not designed to arrest falls from a height;
• the system is not designed for work situations where the user needs to be supported by a body harness.

A restraint system must be assembled in such a way as to prevent the user from reaching areas or positions where there is a risk of falling from a height. Any suitable body harness and any suitable lanyard may be used. In particular, a restraint system includes: body harness, secure anchorage point and connection system.

A - BODY HARNESS
B - SECURE ANCHORAGE POINT
C - CONNECTION SYSTEM

 

 

WORK POSITIONING SYSTEM

A system which allows the user to work tensioned or suspended in a way that avoids falls. The main characteristics of a generic work positioning system are as follows:
• the system prevents the user from falling;
• the system is not designed to arrest falls from a height;
• the system allows users to position themselves in the work area tensioned or suspended.
In work positioning systems the user generally relies on the support equipment; work positioning systems, therefore, do not perform the function of fall arrest, so an auxiliary system to perform this function must be supplied. Moreover, work positioning systems should be adjustable. In particular, the components of work positioning systems include: body harness, secure anchorage point and connection system.

A - BODY HARNESS
B - SECURE ANCHORAGE POINT
C - CONNECTION SYSTEM

 

 

ESSENTIAL GUIDE FACTORS IN PROTECTING AGAINST FALLS FROM A HEIGHT

The personal protective system against falls from a height consists of an assemblage of connected components; for the system to work correctly certain essential factors must be taken into consideration, such as the clearance, the fall factor and the pendulum effect, and how they interact with each other. The assessment of these factors determines which components should be assembled to give adequate protection.

 

CLEARANCE AND FALL FACTOR

CLEARANCE (min H)
The minimum distance from the ground (or from any other protruding object) at which the anchorage point must be positioned to guarantee the user a minimum safe falling space, measured vertically from the anchorage point to the collision surface. Therefore, clearance results from the addition of ΔL which represents the arrest distance of the energy absorber, L which represents the total length of the entire device of the original connection, H which represents the length of the body + 1 m which represents safety distance. To calculate the arrest distance it is necessary to take into account also a possible extension of anchorage point EN 795. The arrest distance of the energy absorber (ΔL) changes in accordance with the change of the total length of the lanyard, of the fall factor and of test mass.

 

FALL FACTOR
The fall factor represents an instant measure of the fall’s level of danger; particularly important are cases where values of 0,1 or 2 are obtained, as shown in the diagrams below. The fall factor is calculated with the formula F= fall height / lanyard length.

 

FALL FACTOR 0
The anchorage point is above the user and the tensioned lanyard immediately arrests any accidental fall. In this case, it is not obligatory to use an energy absorber although its use is strongly recommended. Fall factor 0 represents optimal operating conditions.

 

FALL FACTOR 1
The anchorage point is at the same level as the attachment points on the user’s harness. The fall arrest lanyard is not tensioned and must be integrated with an energy absorber which, being activated only partially, must be able to limit the inevitable kick caused by the fall arrest. Fall factor 1 represents normal operating conditions.

 

FALL FACTOR 2
The anchorage point is below the user, or at the level of their feet. The fall arrest lanyard must be integrated with an energy absorber which, being fully activated given the increased height, must be able to limit the inevitable kick caused by the fall arrest. Fall factor 2 represents critical operating conditions.

 

PENDULUM EFFECT

The dangerous oscillation the user would be subjected to if the anchorage point is not fixed vertically with respect to the actual position of the user. Such lateral oscillation could expose the user to dangerous collisions with close obstacles of different kinds, causing a range of injuries. Often, given the nature of the work zone, it is not possible to secure an anchorage point vertical to the position of the user; in this case oscillation can be prevented by using to different anchorage points situated on both sides of the user.

 

TYPES OF PROTECTION

 

	FALL ARREST SYSTEM	Fall arrest devices are employed simultaneously in order to prevent the injurious fall to the ground of the user.
	RESTRAINT SYSTEM	Fall restraint devices are employed simultaneously in order to prevent the user from reaching a position where there is a risk of falling.
	WORK POSITIONING SYSTEM	Work positioning devices are employed simultaneously in order to maintain the user in a sustained and stable position, enabling them to use both hands while working and in such a way as to prevent a free fall.

 

ATTACHMENT POINTS

 

	DORSAL ATTACHMENT POINT	Device with a single rear dorsal attachment point for fall arrest.
	DORSAL AND STERNAL ATTACHMENT POINTS A/2	Device with two attachment points for fall arrest, one on the rear and one on the front (obtained by connecting two semi-attachment points A/2).
	DORSAL AND LATERAL ATTACHMENT POINT	Device with three attachment points. One on the rear for fall arrest and two lateral points for restraint and work positioning.
	DORSAL, STERNAL A/2 AND LATERAL ATTACHMENT POINTS	Device with four attachment points, one on the rear and one on the front (obtained by connecting two semi-attachment points A/2) for fall arrest, and two on the side for restraint and work positioning.
	LATERAL ATTACHMENT POINT	Device with two lateral attachment points for restraint and work positioning.

 

	A Dorsal anchor point for fall arrest
	A Sternal anchor point for fall arrest
	A/2 Fall arrest semi-attachment points
	Work positioning attachment point