Theatre guides

24 May 2005

Recent years have seen riggers in the entertainment industry adopting rigorous standards for hoisting. Phil Bishop reports

Unsurprisingly, perhaps, it was the Germans that took the lead. In April 1998 the Institution for Statutory Accident Insurance & Prevention (Berufsgenossenschaft VBG) published BGV-C1 (which started life as VBG 70), a code of practice for entertainment and theatrical venues to use for designing their operations. Lifting and rigging equipment is just part of this code. It also covers structures, foundations and other technical matters.

It is not enshrined in law - adopting BGV-C1 is entirely voluntary - but its adoption is generally required by insurance companies in Germany, and therefore it has effectively become an industry standard. It has increasingly become the standard to which entertainment industries in other countries work.

There are certain important differences between the hoist demands of BGV-C1 and general industrial standards familiar to the rest of the lifting industry. This is because in theatres hoists are often used to move loads over performers on stage and then hold them in place. A C1 chain hoist is defined as one that can be used to move and hold loads above people. A D8 chain hoist can be used to lift loads during set up, with the area underneath cleared of people. A D8 Plus chain hoist can hold loads over people, but not move them, with no secondary safety component to hold the load in case of hoist failure.

A C1 hoist has a design factor of 10 to 1 instead of 5 to 1. It has four position limit switches (two working, two emergency). There has to be a system to detect when the chain is slack. This is so that is two or more hoists are lifting in tandem, if one chain becomes slack, another hoist may become overloaded as it runs away with the load. There has to be a double brake. Finally, if the clutch is a load bearing clutch, the overload protection must be provided through an additional method and not through a slipping clutch.

There are three dominant suppliers of chain hoists to the entertainment industry: Liftket (the Chainmaster brand) of Germany, Verlinde (Stagemaker) of France, and Columbus McKinnon (Lodestar) of the USA.

Perhaps unsurprisingly, it is the American company that is most critical of BGV-C1 and it has had to make substantial modifications to its Lodestar in order to meet the German code.

To meet the 10:1 design factor requirement, a BGV-C1 compliant Lodestar has its safe working load halved. For slack chain detection, a load cell is added to the hook and the hoist cuts out when a slack chain is detected. It meets BGV-C1 but in cutting out the slack hoist, any overload on other hoists is increased. This is a clear weakness of the code, says Adrian Forbes Black, Columbus McKinnon’s regional manager for Europe. Before joining Columbus McKinnon in 2003, Black – who is British - worked for many years in the theatrical rigging industry.

Hans van der Moolen, manager of Verlinde’s Stagemaker division, agrees with Black on this point. “We don’t like to promote the underload detection. There is no common sense there. It creates more problems than it solves because in a dynamic situation you always have hoists that are almost running free.” However, he points out that it does not actually cause other hoists to overload, since BVG-C1 also requires overload protection that cuts off not just the overloaded hoist but also the central control system.

In general, however, Van der Moolen is happy with BGV-C1. Black, however, has further criticisms. He is also critical of the braking requirements, for example, because they do not say where the brakes should be or how strong they should be. The AC brake of a 1,000kg SWL Lodestar is designed to stop loads up to 3,750kg. For the BGV-C1 approved version, the only way to fit a second brake in the casing is to use DC brakes, supplied by Stromag. “These two brakes combined have just about the same stopping power as our one brake,” Black says. “It is a typical European standard with no clear facts and figures. We can make the brake out of butter if we want.” He contrasts this with British Standards that require man-lifting winches to have one brake on the motor and one on the gearbox, so wherever the drivetrain fails, the load is protected.

But Van der Moolen disagrees that BGV-C1 lacks detail. “It has to be read with the relevant DIN standards, which are precise.” BGV-C1 does indeed make many references to various DIN standards.

Black thinks the emphasis on brakes in general is misplaced. “We’ve made a million Lodestars in 50 years and never lost a load to brake failure. Brakes are not why you drop loads.”

The Lodestar is the only major chain hoist brand used in the entertainment sector that uses a slipping clutch, so change is required here too to meet BGV-C1. “We get round this by adding an electronic device. BGV-C1 says overload is 120% of SWL. FEM norms for normal industrial hoists say that hoists with a non load bearing clutch should have an overload capacity of 125% to 140% of SWL. If it is a load bearing clutch, then it’s down to the manufacturer’s discretion. A new Lodestar will probably start to slip at around 160%. So, given that our 1,000kg hoist is rated at 500kg for BGV-C1, failure at 1,600kg is more than three times the SWL.”

The end result, Black says, is that Columbus McKinnon’s BGV-C1 Lodestar is “twice the price for half the hoist”, because of the added features and the halved SWL.

Black also questions the value of the time, money and effort that goes into meeting BGV-C1. “Most loads fall from hoists due to human error or bad maintenance. Chain hoists don’t fall from roofs very often. BGV-C1 doesn’t address the cause of 95% of accidents, which is human error. It is an expensive way of tackling 5% of accidents. For $50, a self-locking hook would cut our 30% of accidents.” He says when BGV-C1 was produced “the industry was never asked about the causes of accidents”.

Van der Moolen retorts: “Higher safety factors reduce the risk of human error.”

Columbus McKinnon only began producing its own BGV-C1 Lodestar in September 2004. Until then, its German distributor, Pfaff Silberblau, made the conversions with the manufacturer’s agreement. But as worldwide market demand rose, Columbus McKinnon needed to offer it on a worldwide basis.

There is also now a second Columbus McKinnon chain hoist that meets BGV-C1, produced by Coffing and distributed exclusively in Europe and Asia by staging equipment manufacturer Prolyte of the Netherlands as the Prolyft Performance C-ONE. The hoist is produced by Coffing to Prolyte’s specifications. Its criticisms, therefore, are not based on an inability to compete in the market.

To the bare bones of the BGV-C1 much flesh was added in December 2004 when VPLT, the German sound and light industry’s trade association, published a fuller code of practice, SR2.0 Codes of practice for event technology. It corrects one of the weaknesses of BGV-C1, putting emphasis on overload monitoring leading to automatic shutdown rather than slack chain (underload) detection.

While BGV-C1 comes from the perspective of the insurers and the safety authorities, SR2.0 is more of a user’s manual.

FEM, the European Materials Handling Federation, has also entered the fray, producing in August 2004 the manufacturers’ standard FEM 9.756 Hand operated and power driven hoists for special purposes. While BGV-C1 and the VPLT guidance make reference to German DIN standards, FEM 9.756 refers to European EN standards. It is much more specific than BGV-C1, Black says, adding that it is starting to become adopted in non-German speaking countries.

“We’re quite happy with it. We think it is a good compromise,” he says.

BGV-C1 was driven by Germany’s insurance industry and it will be up to insurers to allow FEM to be adopted as the primary standard instead. Manufacturers do not want to be producing three or four different versions of the same chain hoist, so unless Germany adopts FEM, the rigorous demands of BGV-C1 will remain the standard to which chain hoist manufacturers default to, Black says.

Matthias Hühn, managing director of Liftket, says that BGV-C1 meets the needs of the entertainment industry better than the FEM standard. “In our opinion the BGV-C1 standard is the most important for Europe and FEM does not have a wide spread popularity. The reason is that BGV-C1 has been worked out by a team of specialists out of many different branches and offices (Berufsgenossenschaften, theatre people, TV and studio engineers, stage makers and many more). Therefore it meets much more the realistic requirements of stages,” he says.

Hühn continues: “Secondly, it is not a static regulation. It may be different for each specific requirement. Talking about slack chain prevention, it is not necessary to include slack chain detection in any single hoist but essential if loads are guided in a frame or tower where they could jam or if many hoists carry the same load, especially in case of bad visibility.”

Van der Moolen, however, who was on the committee that produced the FEM standard, says that FEM 9.756 is not substantially any different in its requirements to BGV C-1, except for the fact that it does not require slack chain detection. “There are no significant differences. FEM is more detailed in product design criteria,” he says.

He adds that in due course, perhaps in five years, FEM 9.756 will become a European Norm (EN).

The American Entertainment Stage & Theatre Association (ESTA) is now working on its own chain hoist standard, but Black says it will be very different from the demands of Europe. “It will be more based on existing design standards,” he says, “but with de-rating. You won’t need a whole new hoist.”

HOIST has seen a draft of the ESTA standard - BSR E1.6-2 Entertainment Technology – Electric chain hoists for rigging purposes. It is indeed generally much less prescriptive than the comparable European documents except with regard to such procedural criteria as inspections, documentation, training programmes and quality assurance.

Van der Moolen rejects Columbus McKinnon’s criticisms, saying that they simply reflect the different attitudes to standards seen in America and Europe. He is also on the ESTA committee producing standards for both chain hoist and wire rope hoists. This work has already been in the pipeline for seven years, he says. In March this year it was finally concluded that it was not possible to produce a single document for both wire rope hoists and chain hoists because of differences of opinion over wording and over safety factors. Instead, separate documents are being produced for each.

Van der Moolen concludes: “In Europe, safety is put ahead of the personal interest of the manufacturer. I have seen a totally different approach in the US, based not on risk assessment but on product liability.”

Stage hoist in action Stage hoist in action
Verlinde hoists support De Boerderij Verlinde hoists support De Boerderij
ChainMaster's VarioLift ChainMaster's VarioLift
Eurovision song contest, 2001 Eurovision song contest, 2001
The Prolyft 2t hoist on site in Moscow's Red Square The Prolyft 2t hoist on site in Moscow's Red Square
Reed Rigging hoist and truss Reed Rigging hoist and truss
De Boerderij up close De Boerderij up close
Verlinde's Stagemaker hand chain block Verlinde's Stagemaker hand chain block