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In our Brühl glossary, we have summarized all relevant terminology for machines and plant safety through Brühl safety fence systems. Ordered alphabetically, you will find the term that is important to you and its explanation by simply clicking on the corresponding field.

Dimension between axes

Dimension of a component from the middle of the first post to the middle of the second post.

Door opening direction

The opening direction is determined from the stop side. The stop side of a door is the side to which the door hinges are attached. A distinction is made here between DIN left (stop left) or DIN right (stop right).

Opening outwards

By default, the swing doors are designed in a way that the door leaf opens outwards (i.e., towards the operator side).

Ground clearance

Height from the ground to the lower edge of the grid element.
Ground clearance + grid height = fence height

Opening inwards

With inward-opening doors, the wings open towards the machine side. This may be necessary if, for example, there is not enough space outside. It must be checked whether this is permissible in the respective safety concept. For escape doors this option does not exist. You always have to open in the direction of escape to the outside.

Frequency converter

The frequency converter changes the mains frequency of the alternating voltage (three-phase frequency) from 50 Hz to an adjustable value. The speed of the connected motor depends directly on the three-phase frequency and can therefore be controlled by the frequency converter. The gate can therefore be steered steplessly slower and faster, and functions such as "crawl speed" or "slow start" are possible.

Hazard area

Area in or around a machine where a person is at risk of injury or damage to health.
The danger can be:

• either permanently during the intended use of the machine (movement of hazardous moving parts, electric arc during a welding phase, etc.)
• or unexpected (inadvertent, unexpected startup, etc.).

Identification of hazards

The machine must have all the markings required for safe use, for example:
• maximum speed of rotating parts,
• highest load capacity,
• the need to wear protective equipment,
• setting values ​​for the separating safety guard,
• frequency of inspections, etc.

The labels on the machine should remain durable and readable for the expected lifetime. Signs or written warnings only with the words "Danger" must not be used. Markings, signs and written warnings must be easy to understand and clearly related to the particular sub-function of the machine. Well-understandable signs (pictograms) should preferably be used before written warnings. Only signs and pictograms should be used which are understandable in the culture in which the machine is to be used. Written warnings must be in the language of the country where the machine is used for the first time and, if requested, in the language understandable to the operators. According to machine safety standards, such markings belong to the indicative safety technology (user information regarding the residual risk).

Grid elements

A grid element is part of a barrier of an area, usually by means of a complex fencing of the respective danger area. Grid elements in combination with posts result in a protective fence system.

Grid height

The grid height is the height of a grid element.
Grid height + ground clearance = fence height.

Transom profile

The transom profile is a horizontal connecting element of the frame, above the door leaf. This combination of the fighter profile with the hinge and the stop post increases the rigidity of the door portal.

Conventional safety switches

Electromechanical safety switches equipped either with an integrated actuator (type 1) or with a separate actuator (type 2).

Clear width

The clear width corresponds to the actual passage width of doors.

Clear height

The clear height corresponds to the actual passage height for doors from the floor to the lower edge of the door sills.


Manipulation is the deliberate overriding or bypassing of protective devices and their components. Safety switches and other safety devices must be such that the protective function can not be changed or bypassed by hand or with a simple aid. Simple aids are:
• nails,
• pieces of wire,
• adhesive strips etc.

No bypassing in a simple way (according to BGI 575) is:
• disassembly of parts,
• turning the safety switch away from its protective position,
The use of a second actuator,
• bridging the contacts, etc.

In terms of design, it should be borne in mind that despite protective devices, simple and proper operation of machines and systems is possible.

Machine safety

Machine safety describes colloquially protective measures on machines and systems with the aim of avoiding dangerous situations and their risks. The subject of machine safety is considered from two perspectives. For the manufacturer of the machine it is important to place safe machines on the basis of the Machinery Directive and to consider safety measures during the design phase. The operator of a machine or plant is responsible for ensuring safe work with and on the machine to protect its employees.

Average speed

The average speed corresponds to an average of the different production speeds.

Performance Level (PL)

Discrete level that specifies the ability of safety-related parts of a controller to perform a safety function under predictable conditions (as defined by EN 13849). More simply, the performance level is a measure of the reliability of a security function. One distinguishes between the performance level to be achieved (PLr, the "r" stands for "required") and the "actual" PL, which is actually reached. There are five performance levels that stand for different residual risks.


Compared to other plastics, polycarbonate is used where they are too soft, too fragile, too scratch-resistant, too little dimensionally stable or not clear enough. Polycarbonate is crystal clear, can be dyed, welded and glued. In addition, it is very dimensionally stable and has a high impact resistance.

Position switches

Position switches are used to detect a position of movable guards. As soon as a position switch is used as a safety-relevant component, this is referred to as a position switch with safety function or a safety-related position switch. In this case, the switching element must contain at least one positive opener.


By the latch tongue, the actuator is guided mechanically when entering the safety switch. The door frame mounted part of the latch consists of a protruding latch tongue in a guide, a handle and the actuator. On the post side, the bolt receptacle and the safety switch are attached. The latch receptacle, when closed, catches the forces on the door that would otherwise act on the switch and actuator and could damage these components.

Anti-slip property/class

Slip classes determine the slip resistance or the surface properties of floor coverings, for example.

Safety Integrity Level (SIL)

Safety Integrity Level is the level that describes the likelihood that a safety-related system will perform the required safety functions under all specified conditions within a specified time period as required. To do this, one compares the Safety Integrity Level to be achieved (SILr, the "r" stands for "required") with the "actual" SIL that is reached.

Safety edge

A safety edge recognizes a person or their body part or an object under pressure on the effective actuating surface. It is a linear protective device with contact function. Its task is to avoid possible danger situations for a person within a danger area such as shearing and pinching edges. Typical areas of application are door and gate systems, moving units on machines, platforms and lifting devices.

Safety equipment

Safety equipment is intended to protect persons, production material and the environment from danger. A distinction is made between guards and non-guards.


A protective measure is a means of reducing the risk. A distinction is made in protective measures on the constructive side and protective measures when operating the system.

Weld mesh / spot weld mesh

Smooth, drawn wires made of steel or stainless steel are used to make spot weld meshes. These are connected at the crossing points by electrical resistance spot welding at right angles. The welded nodes give the mesh its extremely high stability.

Phenolic plywood

Phenolic plywood plates are plywood plates with an anti-slip surface, which are frequently used in vehicle construction and for hard-wearing industrial floors.

Support means monitoring

The support means monitoring is an electromechanical safety device to prevent a crash of the gate by signal triggering in case of breakage of a support chain. Brühl doors with suspension monitoring always have several suspension elements and are designed so that in the event of failure of a suspension element to signal triggering of the support means monitoring and the other support means keeps the wing in position. Furthermore, a faulty behavior of the track unit can be registered via the support means monitoring, whereby the wing comes to a standstill immediately.

Chequer plate

The chequer plate is a durable and non-slip textured sheet metal. By rolling the sheets get their almond-shaped "chequers". The bottom, however, remains smooth. The arrangement of the chequers is designed in a way that a high slip resistance is given and an optimal liquid flow is ensured.

Laminated safety glass

Laminated safety glass consists of at least two panes of glass, between which a security foil is inserted. There is thus no risk of injury in the event of glass breakage, since the pane does not shatter, despite innumerable cracks.

Laminated safety glass with soundproofing

In the case of laminated safety glass with soundproofing, a 1 mm thick layer of cast resin or a soundproofing foil is used instead of the safety foil. In both cases, very good sound insulation values can be achieved.

Fence height

The fence height corresponds to the total height of the protective fence from the floor to the top of the fence element. Fence height = ground clearance + grid height.