ANSI/ASSE Z359.14:2014 self-retracting devices
Considering the US legislation which covers these fall arrest products.
Self-retractable devices (SRDs), which includes self-retractable lanyards (SRLs), provide a means of attachment between the user and anchorage point. SRLs are important tools for workers needing to climb short to medium (2-50m) distances, so it is vital that they provide safety at all times across their entire working range. SRLs automatically adjust their length as the user moves/climbs, thereby helping to improve freedom of movement. During a fall, the device’s internal mechanics stop the user falling by locking the lifeline. The user’s fall is arrested gradually by slowing the rate of descent and keeping the force to an acceptable limit, compared to the sudden stop experienced when a car seat belt operates in the event of a front-end collision.
The relevant standard for testing an SRL for the US market is ANSI/ASSE Z359.14:2014, which is part of the ANSI/ASSE Z359 fall arrest standard range. This document gives requirements for the design, performance, marking and user information needed before such a device can be marked as compliant to this standard.
Since the introduction of a further standard into the Z359 range (ANSI/ASSE Z359.7:2019 – ‘Qualification and verification testing’), several changes have been made that manufacturers must follow before being able to mark an SRL as ANSI Z359.14:2014 compliant. These are as follows:
1. It is now a requirement in ANSI/ASSE Z359.7:2019 to have the qualification testing carried out by an ISO 17025-accredited laboratory such as SATRA, with the specific standard present on its testing scope. Should this be an accredited manufacturer’s laboratory, the testing shall be witnessed and verified by either a third-party test laboratory representative or by a professional engineer.
2. The minimum number of tests results that are required for qualification testing has increased. Now, a new product must be fully tested a minimum of three times to gain the ANSI mark.
3. Verification testing is now also required to be conducted at an interval not to exceed two years, unless the manufacturer has a robust quality management programme, when the interval shall not exceed five years. For example, having an internal quality procedure would mean verification testing being conducted at least once every two years, whereas being accredited to ISO 9001 would allow up to a maximum of five years between retesting. Verification testing is again required to be carried out by an ISO 17025-accredited laboratory as detailed in point 1.
There are several types of SRD which include SRLs, self-retracting lanyards with integrated rescue function (SRL-Rs), that have a function allowing the user to be rescued after a fall, and self-retracting lanyards with leading edge capability (SRL-LEs), which permit horizontal use with the possibility of falling over a sharp edge.
The main physical tests that all SRDs are required to pass before being marked as compliant to ANSI/ASSE Z359.14:2014 include:
Design requirements – Clauses 3.1.1 - 3.1.4 require the retractable lanyard to include certain design elements. Snaphooks and carabiners should meet the requirements of ANSI/ASSE Z359.12. The locking function shall be automatic, impossible to over-ride when in use and perform correctly ‘even after casual interference’. The energy absorption shall be available throughout the working length of the device for all SRDs, so that the performance remains consistent wherever a fall occurs. A visual indicator shall be provided that deploys during every dynamic test in clause 3.1.9. It is to be clearly visible once activated, so any potential users can see if the device has previously arrested a fall before using the retractable lanyard.
Corrosion Protection – Clause 3.1.5 requires that corrosion protection is provided to the device, so that at a minimum the device continues to operate as intended and shows no signs of corrosion which, if left unchecked, could result in a corrosion-related failure of the device. This is tested by placing the samples in a chamber with the lifeline fully extracted. A mist of 5 per cent salt solution is then sprayed into the chamber for a continuous 96-hour period. Following this period, the samples are then assessed to see if their function has been impaired. This includes carrying out the retraction tension again as specified in clause 3.1.6.
Retraction tension – Clause 3.1.6 requires that all retractable lanyards can retract the lifeline with a force of between 1.25lbs (5.55N) and 25lbs (111.1N) inclusive. This is assessed by hanging the SRD on an anchorage point and measuring the force required to retract the lifeline with one foot (305mm) of the line extracted (figure 1). The test is then repeated with 20 per cent, 40 per cent, 60 per cent, 80 per cent and 100 per cent of the manufacturer’s specified lifeline length extracted. This ensures that the retractable lanyard can retract the lifeline throughout the specified line length. An SRL and SRL-R should have no more than 24 inches (610mm) and an SRL-LE shall have no more than 60 inches (1.5m) of lanyard remaining extended when the device is fully retracted. Additionally, SRL-LEs are required to retract without stopping when tested in a horizontal orientation.
Static strength – Clause 3.1.7 requires that all retractable lanyards can sustain a tensile load of 3,000lbs (13.3kN) statically applied. The test requires the load to be held for one minute. Again, this test produces conditions in excess of what would happen in a normal fall situation to ensure that there is a factor of safety built into the device.
Dynamic strength – Clause 3.1.8 requires all SRDs to be overloaded dynamically, using a 300lb (136kg) test mass dropped with a free fall of 4 feet (1.2m), the retraction being blocked until this fall height has been reached. For an SRL-LE, a 300lb (136kg) mass is dropped from a height of 5 feet (1.5m) and at a horizontal distance of 20 to 30 inches (0.5m-0.75m) from above a sharp edge which has a 0.13mm radius. The device only needs to hold the test mass. No requirement is given for arrest distance or force, as this produces conditions in excess of what would happen in a normal fall situation – it is just to ensure a factor of safety built into the device in terms of overall strength. Following the dynamic strength test, SRLs and SRL-Rs need to be able to retain a minimum of 1,000lbs (4.4kN) of residual tensile strength.
Dynamic performance – Clause 3.1.9 requires all SRDs to be able to hold a dynamic load when dropped with no initial free fall, using a 282lb (128kg) mass – see figure 2. For an SRL-LE, a 282lb (128kg) mass is dropped from a height of 5 feet (1.5m) above an edge with a radius of 0.13mm. All SRDs are required arrest the load, while keeping the peak and average arrest force along with the arrest distance to a minimum. The requirement values are dependent on what type of SRD the device is and whether the retractable lanyard is class ‘A’ or class ‘B’ (see table 1). This test needs to be conducted after the retractable lanyard has been pre-conditioned in ambient, wet, cold and hot humid environments. These tests simulate a real fall in a variety of potential conditions. After each dynamic test, the SRLs, SRL-Rs and SRL-LEs (except following edge test) are required to still function correctly in accordance with clause 3.1.6 (retraction tension). SRL-LEs are required to retain a minimum of 675lbs (3kN) for wire ropes or 1,000lbs (4.5kN) for synthetic lanyards, following the dynamic test while still in the same position.
SRL-Rs which allow the user to be winched to safety following a fall have additional requirements for these types of devices, as follows:
Design requirements – Clauses 3.2.1 and 3.2.2 require that the SRL-R can engage its rescue mode of operation at any time, subject to manufacturer’s instructions, while not being able to inadvertently change to or from rescue mode without a user intentionally doing so. The minimum mechanical advantage given by the rescue feature shall be a minimum of 3:1, and the device shall be capable of raising or lowering the load to effect a rescue. If the rescuer relinquishes control at any point, the SRL-R shall automatically stop and hold the load. A means of stabilising the device during a rescue shall be incorporated.
Static Strength – Clause 3.2.3 requires the SRL-R to sustain a tensile load of 3,000lbs (13.3kN), statically applied when the rescue function is engaged. The test requires the load to be held for one minute.
Rescue, post fall arrest – Clause 3.2.4 requires the rescue mode to be engaged (following all dynamic tests mentioned previously for SRL-Rs), and then to simulate a rescue using that particular function. This involves raising the mass half the arrest distance or sufficient to allow lowering then, once there, releasing the handle of the rescue device checking that the mass stops within four inches (102mm). The mass is then lowered to the ground.
Function – Clause 3.2.5 requires the rescue mode of the SRL-R to be checked that both 75 per cent of the minimum and 125 per cent of the maximum user weight capacity can be lifted and lowered. This ensures that all users can be successfully rescued in the event of a fall. This test requires the corrosion samples to be used to try and raise the two different weights three feet (0.9m), when six feet (1.8m) of lifeline is extracted from the SRL-R. The handle is then released and left for one minute, then the length of life-line extracted from the device is measured to calculate the vertical displacement. The mass is then lowered to the ground.
As mentioned in the dynamic performance test section, different requirements are set out for SRLs, SRL-Rs and SRL-LEs of classes A and B. Table 1 gives details on the differences.
|Table 1: Product requirements|
|SRL, SRL-R and SRL-LE|
|Class A||Class B|
|Maximum peak arrest force||1,800lbs (8kN)||1,800lbs (8kN)||1,800lbs (8kN)||1,800lbs (8kN)|
|Maximum average arresting force||1,350lbs (6kN)||1,575lbs (7kN)||900lbs (4kN)||1,125lbs (5kN)|
|Maximum arrest distance||24 inches**||24 inches**||54 inches**||54 inches**|
|* Wet, cold and hot and humid conditions
** Not required for SRL-LEs, but should be recorded
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