GC Covers: Sizes, Types and Equipment

The company mission is: to manufacture products for the environmental sector and, with the aid of product- and technical development, make these products more functional, environmentally-friendly and easy-to-operate. This creates a better working environment for the people using the products as part of their work.

The company manufactures a number of core products for the environmental sector, including covers developed and improved with the company mission in mind. The spring assist system, for example, can reduce the opening force to just 10 -15 kg for heavy covers with a lid weighing up to 1,000 kg.

 

A: Load and Location.

Covers from Gerhardt Christensen A/S are produced according to European Standard DS/EN 124 and in the load classes specified by DS/EN 124. See Figure 9a and Table 1. To meet the requirements of DS/EN 124, the strength of the covers are checked by the Aarhus Institute of Technology, providing certainty of compliance with DS/EN 124.

 

Figur 9a

 

 

Group Class Load Application
1 A15 15 kN Places and footpaths primarily used by pedestrians and cyclists.
2 B125 125 kN Access roads associated with pedestrian zones and parking lots for cars.
3 C250 250 kN For footpaths and kerbs, where parking may occur. May reach max. 0.5 m into the roadway.
4 D400 400 kN For places with access for all types of vehicles, such as roads, emergency lanes, escape routes, pedestrian malls, car parks.
5 E600 600 kN For places exposed to high wheel loads, such as docks, airports etc.
6 F900 900 kN For places exposed to very high wheel loads, such as airports.

B: Clear Opening for Covers.

Gerhardt Christensen A/S makes rabbeted and recessed covers to measure and in the following standard types.

Standard dimensions for rabbeted and recessed covers: See table 2.

 

Table 2: Standard Sizes

Kept in stock
Inside measure in mm Rabbeted Recessed
600 X 600
600 X 800 X
660 X 820 X
800 X 800
1000 X 600
1000 X 800
1000 X 1000
1100 X 1100
1200 X 800
1200 X 1000 X X
1200 X 1200
1320 X 820 X

 

C: Functional Requirements:

Standard covers from Gerhardt Christensen A/S are manufactured according to the following guidelines:

 

 

Load:

Walking load equivalent to 2 kN.

 

Standard sizes:

See table 2.

 

Choice of Material:

Lids are made from quintet aluminium floor plates of a sea-water-resistant quality as per EN AW-5754-AlMg3.

The cover frame can be made from the following materials:
Steel St37 hot-dip galvanized as per DS/EN ISO 1461-1999 and stainless steel AISI 304 or AISI 316.

 

Safety support for the lid:

For safety reasons, lightweight rabbeted and recessed covers are always equipped with a safety support for the lid, preventing unintentional closing when work is carried out at the cover.
Apart from the safety support for the lid, additional equipment for the cover should be chosen based on the location and function of the cover. See Table 3.

 

Solid recessed covers.

 

Load:

The load class of the cover is determined acc. to Figure 9a and Table 2 and is usually in the range from A15 = 15 kN to D 400 = 400 kN. Covers in the classes E600 and F900 rarely occur and are specially made.

 

Standard sizes:

See Table 2.

 

Greased bearings:

In order to comply with an opening force of max. 10-15 kg, covers above a certain size and weight are equipped with greased bearings.

 

Choice of Material:

As standard, the lid and frame are made from steel St37, hot-dip galvanized as per DS/EN ISO 1461-1999.
In special cases the lid and frame can be made from stainless steel AISI 304 or AISI 316

 

Safety support for the lid:

For safety reasons, hinged recessed covers are always equipped with a safety support for the lid, preventing unintentional closing when work is carried out at the cover.

Apart from the safety support for the lid, additional equipment for the cover should be chosen based on the location and function of the cover. See Table 3.

 

D: Type Designation and Extra Equipment.

The following table specifies the designations and available extra equipment.

 

Table 3: Type Designation and Extra Equipment.

Type Inside measure Material Load Spring Assist Extra Equipment
PF Specify inside measure L x W in cm
L: hinged side
AA Specify in kN

or use:
A15
B125
C250
D400

Specify desired lifting force in kg

Fxx

B – Locking bolts – light traffic load
OF AS P – Locking bolts – heavy traffic load
FD AR C – Latch
AF E – Balusters + chain
ST R – Safety grid, loose
RR E+R – Combined safety grid and railing. Hinged in cover frame.
FF
H – Internal handle
I – Insulation
K – Floating frame
KBH – Mortice lock
L – Padlock fitting
M – Covering
N – T-key hole
T -Smell tight
T(water) – Water tight
U – Vent cap
X – Panic lock

 

Abbreviations:

 

Type:
PF: Recessed cover

OF: Rabbeted cover

FD: Recessed cover with hidden floating hinges
Material:
AA: Aluminium lid and aluminium frame

AS: Aluminium lid and hot-dip galvanized steel frame

AR: Aluminium lid and stainless steel frame

AF: Aluminium lid and acid-resistant steel frame

ST: Lid and frame of hot-dip galvanized steel

RR: Lid and frame of stainless steel

FF: Lid and frame of acid-resistant steel
From the extra equipment mentioned in the table, the following is described:

B: Locking bolts
The purpose of the locking bolts is to tighten the lid to the frame so it doesn’t “rattle” when the lid is driven on. The nut of the locking bolt in the frame is shaped and placed in such a way that sand and dirt from the road cannot accumulate in the nut.

 

Locking bolts and nuts for cover frames are available in the following designs:

Locking bolt A2-70 Nut st. 37 Inserts Chrome Nickel steel
M16 M16 No inserts
M16 Spring impact M24 M16/M24 replaceable
M20 M20 No inserts
M24 Spring impact M33 M24/M33 replaceable
F: Spring system
Spring system to ensure that the opening force does not exceed the allowed 10 – 15 kg.

The spring in our system is a powder coated coil spring in a stainless telescopic tube. The ends of the telescopic tube are made from bronze.

The combination of stainless tube, ends of bronze and a powder coated spring of high-strength steel ensures a highly corrosion-safe design.

The advantage of a coil spring over a gas spring is, that when the lid is open and weighs almost nothing, the coil spring is extended and as such has no force, as opposed to the gas spring, which has an almost even force throughout its entire travel.

Subsequently, Gerhardt Christensen do not use gas springs in their covers.
 
If gas springs are used, the following should be observed:
  • When a cover is assisted by gas springs, there is a risk that the closing force will be equal to, or greater than the opening force. At the same time, it will become difficult or impossible to comply with the Danish WorkCover authority notification no.4.05.02. Assessment of lift. ( 10 to 15 kg open – close force )
  • The surface treatment of the gas spring is usually black enamel with a hard chrome plated piston rod, i.e. not stainless.
  • Gas springs have a very high pressure in the cylinder (up to 300 bar) and are not to be opened under any circumstances.
  • When disposing of / recycling gas springs. Gas springs mainly consist of metal and can be handed in for material recycling, however, the gas pressure has to first be released from the cylinder. In this case, oil must be separately removed and disposed of.

R: Safety grid:

The safety grid can be loose or hinged.

E+R: Combined safety grid and railing.

The safety grid operates as safety grid in horizontal position. And as railing in vertical position; this is achieved when the lid is open and the grid is raised to vertical position.

The safety grid railing is dimensioned according to DS 410 page 40 , 13.1.5 with a horizontal force equal to 0.8 kN / m.

P: Wedge system ensuring that the lid does not move in the frame with a dynamically moving load – traffic load.

At the same time the table serves to determine the type of cover as per the following system:

PF-142×083-ST-D400-B-F10-H possibly two-part, four-part etc.

The above example indicates a recessed cover with inside measure of 1,420mm (hinged side) x 830mm and steel lid and frame. The cover is dimensioned for a 400kN load and equipped with locking bolts, spring system and internal handle.

 

 

Table 1: Extracts from DIN/EN 124 with added fields of application