The cover has ventilation holes as prescribed within European Standard EN 124. Accordingly, for a cover with 600 mm clear opening, the total air inlet section has to amount to 140 cm².
Covers with vent holes can yet be rendered surface-watertight. For this, a dirt pan with encircling drainage channel is fitted below the cover. From the drainage channel the penetrated surface water is lead to an outlet point connecting to the drainage system on site.
Renders cover tight against ingress of pressureless surface water. Surface-watertight access covers may not be flooded permanently!
Surface water penetrates through cover and is collected by means of combined inner cover with encircling drainage channel. This needs connection to a local drainage system (e.g. soak-away bed).
Water pressure from above. Cover is fitted with adequate locking devices and sealed accordingly. Dimensioning as per customer's information in respect of expected frequeny of overdamming (in millimeter or water column pressure/bar). Customer/installer must ensure proper anchoring and sealing between cover unit and shaft structure.
Water pressure from below. Sealing and locking of cover are designed in relation to the backpressure expected on site. Depending on size of cover and expected backpressure intensity, a screwed-down inner cover may be required. Ingressing surface water is drained via an encircling drainage channel. With single cover units, the top cover itself can be rendered backflow-proof. The frame must be anchored to the frame structure in relation to the backpressure to be expected. For this, the frame comes shaped accordingly (fixing material locally).
Gastight against gases of atmospheric pressure. In general meant only for sewer gases – if needed for other gases, please consult us.
The frame is fitted into a locally provided bushing. This secures it against shifting due to braking or turning wheels on top of cover.
The frame must be securely anchored (plugged) to the shaft top. For this, the frame comes with relevant apertures. Dimensioning and type of fixing is in the responsibility of the installer. We gladly assist with advice. Cover units for embedding into concrete can be welded to the reinforcement iron – provided the materials are compatible.
Hinged covers are easier to open – even without assist-lift. Securing against accidental closing: either by opening cover to an angle of >105 ° or by cover hold-open latches.
Covers are fitted with gas rams for easier opening. Cover opens to 88/89 degrees only, hence cover hold-open latches are required!
overs are hinged to the frame and opened by means of hydraulic cylinder(s). Opening and closing can be effected by electric-driven hydraulic aggregate or by hand- or foot-operated pump. This opening system is particularly well suited for covers of large dimensions and high load classes, such as used in harbours, airports, container ports, certain industrial areas and for emergency exits (in this case, cover opening is from inside).
Here, covers are fitted at underside with a thermal insulation panel, covered by metal sheating.
Covers can be equipped to conform to fire resistance classes F 30, F 60 or F 90 (figures expressing resistance time in minutes). Fire protection is possible on one or on both sides of cover. Verification of resistance class is confirmed by expert certificate, available on request, with delivery documents.
The type of locking chosen depends on the sealing effect sought:
Locking by bolt in cover and thread in frame. Particularly suited to achieve high compression strength for high sealing effect. In place of commercial type of bolt heads, special heads (hex./square/hollow) are available to increase protection against unauthorized cover opening.
"Nontensional" type of locking, does not transmit traffic load from cover to frame. Its main idea is to protect cover/shaft from unwanted opening and access (theft, vandalism etc.). In place of commercial type of bolt heads, special heads (hex./square/hollow) are available to increase protection effect.
Force-locking (cover to frame) by spring and thread bolt. Works like a latch but requires pre-stressing. Main advantages: no loose parts and no open threaded sleeves. Serves both for sealing of cover and safeguarding it against unwanted opening. In place of commercial type of bolt heads, special heads (hex./square or hollow) are available to increase protection effect.
The use of profile cylinder inserts or central locking mechanisms – and of other special locking devices – also allows the use of safety-profile split-cylinder locks for securing cover in frame.
Serves to open cover manually from below by one single handle. (Force-locking mechanism, can be re-adjusted)
EJ Deutschland GmbH Hellerwaldstr.6 56154 Boppard Germany Phone: 0049 (0)67428722-0 Fax: 0049 (0)67428722-50