GB2507034A

GB2507034A - Safety post and fall arrest system

Info

Publication number: GB2507034A
Application number: GB201216419A
Authority: GB
Inventors: Andrew Davis
Original assignee: UNIVERSAL SAFETY SYSTEMS Ltd
Current assignee: UNIVERSAL SAFETY SYSTEMS Ltd
Priority date: 2012-09-14
Filing date: 2012-09-14
Publication date: 2014-04-23
Also published as: GB201216419D0

Abstract

A safety post for use in a fall arrest system includes a base fitting (26) for attachment in use directly or indirectly to a roof element; an upper fitting (28) for connection in use directly or indirectly to a safety line, and a body portion (24) of plastics material. The base fitting (26) and the upper fitting (28) are at least partially embedded in said body portion (24), whereby in use on application of a shock loading to said upper fitting, the body portion (24) deforms to moderate the shock loading transmitted to the base fitting.

Description

Safety Post and Fall Arrest System This invention relates to safety posts for use in a fall arrest system as well as to fall arrest systems including said safety posts. In particular, but not exclusively, the invention relates to safety posts in use in a fall arrest system in which a horizontal safety line is supported between an arrangement of posts.

However the invention also extends to posts that may be used for other purposes such as e.g. single point attachment.

In a fall arrest system which uses a horizontal safety line, a safety line is secured to a roof or other building structure between a pair of end posts at the end of the run of the safety line. Between the two end posts, there may be corner posts where the line changes direction, and intermediate posts disposed between the end posts and any corner post. A person working on the roof or other area at risk of a fall will be provided with a safety harness and a lanyard which can be coupled onto the safety line by a suitable connector and which typically can slide along the length of the horizontal line past the posts without requiring disconnection.

Due to the geometric considerations, should a person fall and be arrested by the system, the resolved forces transmitted along the lines to the posts, and particularly the corner and end posts, is high and the resultant shock loading can cause damage to the roof structure. The lanyard and/or harness may have some form of shock absorption but it is found that the horizontal line and its supports need to be provided with shock absorption characteristics to prevent or limit damage to the roof. The safety posts are typically connected to a base plate which is configured for the particular type of roof building structure on which the system is installed. Thus, different plates may be used for membrane roofs, various roof claddings, standing seam roofs and so on.

It is known to provide safety posts which provide shock absorption by toppling over in the event of a shock load and which are provided with a metal coil spring and/or plastically extendable element which unravels to provide damping. Such posts are complicated in design and manufacture and, once used, cannot be redeployed.

We have therefore designed a safety post for use in a fall arrest system which provides shock absorbing characteristics which overcomes or mitigates at least some of the above disadvantages.

Accordingly, in one aspect this invention provides a safety post for use in a fall arrest system, said safety post including: a base fitting for attachment in use directly or indirectly to a roof element; an upper fitting for connection in use directly or indirectly to a safety line, and a body portion of plastics material, wherein the base fitting and the upper fitting are at least partially embedded in said body portion, whereby in use on application of a shock loading to said upper fitting, the body portion deforms to moderate the shock loading transmitted to the base fitting.

In this arrangement the provision of the plastics body provides a simple yet effective means for moderating the shock load transmitted by the post into the roof structure in use.

Although in some instances the plastics body may provide the only connection between the base and upper fittings, for example where the post is to be used as an intermediate post, the base fitting and the upper fitting are also conveniently interconnected by a tie element. The tie element may conveniently include a chain linking the two fittings. The fittings may be connected to their respective associated components in any suitable way but it is preferred for at least one of said fittings to include a thread for engaging a cooperating element, or another rotary connection such as a bayonet connection.

At least one of said fittings conveniently includes a loop formation embedded in the plastics material of said body portion; thus the fitting may include be in the form of an eye nut or other element comprising a loop portion and a threaded bore.

Preferably the plastics material forming the body portion includes a polyurethane material. The plastics material conveniently has a Shore A Hardness of at least 80 for safety posts intended to be used as an intermediate post, and a Shore A Hardness of at least 95 for safety posts intended to be used as an end or corner post.

The invention extends to a method of making a safety post as described above, which includes providing a base fitting and an upper fitting, and moulding a body portion of plastics material around at least part of said base fitting and upper fitting, thereby to embed said fittings in the plastics material.

The invention also extends to a fall arrest system itself, including a plurality of safety posts as described above, secured in use to a structural element of a building, with a horizontal safety line passing therebetween.

Whilst the invention has been described above, it extends to any inventive combination or sub-combination of the features set out above, in the

following description, claims or drawings.

By way of example only, one specific embodiment of the invention and various modifications thereof, will now be described in detail, reference being made to the accompanying drawings in which: Figure 1 is a schematic view showing a fall arrest system on a flat roof structure; Figure 2 is a side view of a corner or end post for use in the system illustrated in Figure 1, and Figure 3 is a top plan view of the safety post of Figure 2.

Referring initially to Figure 1, a fall arrest system comprises two end posts 101, a corner post 102 and a number of intermediate posts i03 secured to the roofing structure of a building. A horizontal safety line in the form of a tensioned steel cable 12 passes through fixings 14 secured to the top of the posts 101, 102 and 1 o3. A harness 16 is secured to one end of a lanyard 18 which has at its end a connector 20 which can be connected to the horizontal safety line and slide therealong between the end posts.

The end, corner and intermediate posts 101, 102, i03 are connected to the roof structure by a suitable plate 22 (see Figure 3) which is secured to a structural component of the roof. In the event that a person clipped to the horizontal safety line 14 should fall, they would be restrained by the harness 16 and the lanyard 18, with the loading being transmitted from the lanyard to the horizontal safety line 14 and thence via the posts 101, 102, i03 into the roof structure. In order to dissipate or moderate the shock loading transmitted to the roof structure, the posts are formed to have inherent shock absorbing ability.

Referring now to Figure 2, there is shown a corner and end post in accordance with this invention. The post comprises a body 24 of plastics polyurethane material of Shore A Hardness in the range of from 80 to 95 in which are embedded a base fitting 26 and an upper fitting 28, here in the form of eye nuts, which are interconnected by a short length of chain 30 connecting the eyes. The body 24 is formed by moulding and is made by locating the eye nuts 26, 28 and the interconnecting chain 30 in a mould, and then introducing molten plastics in the mould to flow around the links of the chain and the eyes of the fitting to provide a body with substantially no voids. The eye nuts include threaded portions 32 and 34 respectively into which a bottom fixing such as a threaded bolt 36, and a top connection such as an eye bolt 14 or stub may be threadedly engaged.

In use, having selected and fitted a suitable plate 22 to the roof structure leaving the threaded end ofa bolt 36 upstanding, the safety post 101, 102, io3 is screwed onto the bolt to secure the post to the plate. A top connection 14 is screwed into the upper fitting 28 and, once the various posts 101, 102, 1 o3 have been fitted to define the path of the horizontal safety line 14, the horizontal line is passed through the top connectors, tensioned, and secured at the end posts 101. The user dons a harness 16 and they then secure themselves to the horizontal line 14 using the connector 20 at the end of the lanyard 18. In the event that they should fall from the roof, their mass is transmitted through the harness 16 and lanyard 18 to the horizontal line 14 and thence reacted through the posts 101, 102, i03 into the roof structure. The shock load is moderated by the safety posts deforming under load to absorb some of the shock loading by deformation of the plastics body.

Although all the posts could be of the type shown in Figures 2 and 3, it is acceptable for the intermediate posts i03 to be of simpler construction with just a base fitting 26 and an upper fitting 28, without any interconnecting chain.

Claims

CLAIMS1. A safety post (20) for use in a fall arrest system, said safety post including: a base fitting for attachment in use directly or indirectly to a roof structure; an upper fitting for connection in use directly or indirectly to a safety line 14, and a body portion (24) of plastics material, wherein the base fitting (26) and the upper fitting (28) are at least partially embedded in said body portion, whereby in use on application of a shock loading to said upper fitting, the body portion deforms to moderate the shock loading transmitted to the base fitting.
2. A safety post account to Claim 1, wherein the base fitting (26) and the upper fitting (28) are also interconnected by a tie element (30).
3. A safety post according to Claim 2, wherein said tie element includes a chain (30).
4. A safety post according to any of the preceding Claims, wherein at least one of said fittings (26, 28) includes a thread (32, 34) for engaging a cooperating element.
5. A safety post arrangement according to Claim 4, wherein at least one of said fittings includes an eye nut (26, 28).
6. A safety post according to any of the preceding Claims, wherein said plastics material includes a polyurethane material.
7. A safety post arrangement according to any of the preceding Claims, wherein the plastics material has a Shore A Hardness of at least 80.
8. A safety post arrangement according to any of the preceding Claims, wherein the plastics material has a Shore A Hardness of at least 95.
9. A safety post according to any of the preceding Claims, wherein at least one of said fittings (26, 28) includes a loop formation embedded in the plastics material of said body portion.
10. A method of making a safety post according to any of the preceding Claims, which includes providing a base fitting (26) and an upper fitting (28) and moulding a body portion (24) of plastics material around at least part of said base fitting and upper fitting, thereby to embed said fittings in the plastics material.
11. A fall arrest system including a plurality of safety posts (101, 102, 1 0) according to any of Claims 1 to 9, secured in use to a structural element of a building, with a horizontal safety line (14) passing therebetween.