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In-Tank Valve with pneumatic actuator

Function and Description

PROTEGO® NB/AP in-tank valves are used in storage tanks for cryogenic liquids in order to seal off discharge lines in the event of an accident or emergency (pipe bursting). These devices meet the requirements of API 625.

The device consists of the bottom plate (1) which has to be welded onto the vessel bottom; a nozzle (2) which has to be welded to the discharge line; the flanged fast-acting valve (3) with valve piston (4) and release valve cone (5); and the complete pneumatic actuating device (6) which is mounted onto the roof of the tank. The required tightness is ensured by a lapped metallic valve pallet and relief valve cone.

The quick-release valve (3) and the actuating system (6) are connected by an actuator cable (7). An additional emergency cable enables the quick-release valve to be opened if the main actuator rope is damaged.

During normal operation, a pneumatic cylinder holds the valves in the open position. The pneumatic cylinder is actuated by a control line to lift the valve piston. The bottom valve is only closed in an emergency. In the event of an energy drop, the valve piston, due to its own weight, falls onto the valve seat which closes the bottom valve.(fail safe concept).

The valve design is independent of the nominal size. The nominal size DN 1 is determined by the nominal size of discharge line.

Material selection depends on the substance and the operating temperature.


DN 1 DN 2 abcdefHub
150 / 6"80 / 3"200 / 7.871130 / 44.491430 / 56.30550 / 21.65175 / 6.89465 / 18.31160 / 6.30
200 / 8"80 / 3"200 / 7.871130 / 44.491430 / 56.30600 / 23.62175 / 6.89470 / 18.50160 / 6.30
250 / 10“80 / 3"200 / 7.871130 / 44.491430 / 56.30740 / 29.13175 / 6.89485 / 19.09160 / 6.30
Dimensions in mm / inches

Material of fast action bottom drain valve

Bottom plate with nozzle*
Valve housing with valve coneStainless Steel
Actuator ropeStainless Steel
* upon request


Housing Stainless Steel
Actuator spindleStainless Steel
Guide bushingCopper
Protective capStainless Steel
Pneumatic cylinderAluminium

Data Necessary for Specification

Stored medium
Operating temperature T (°C or °F)
Operating pressure p (bar or psi)
Connection size DN 1
Tank height (m or ft)

Selection and Design

The main process data and product properties of the stored medium as well as the temperature of the stored product determine the material for the specific valve. Subsequently the nominal diameter and the type of connection are checked and selected.

The in-tank valve is available in nominal diameters of DN 150 mm / 6"and DN 200 mm / 8", whereas the connection for the pneumatic actuating device has a nominal diameter of DN 80 mm / 3".

The length of the actuator rope and of the emergency rope is determined by the height of the tank. The final adjustment is completed during installation. The material for the gasket is determined based on the operating conditions and/or other special requirements.

The material of the valve bottom plate needs to be compatible to the material of the tank bottom plate. If the material of the bottom plate is provided by the tank manufacturer, then close coordination between manufacturing planning and installation planningis necessary.

 For special requirements the valve and the actuation system (e.g. with inductive position indicator) can be supplied with a special design.

Deviations from our standard design will be sized and specified with the support of our engineers for the specific application.

Flange connection type

EN 1092-1, Form B, PN 40 or upon request