Quick Closing Valves are, actually, shut off valves that are designed to isolate oil tanks in the event of a fire and also to prevent fuelling of a fire in case of a piping system and its components failure. These valves are designed to be remotely operated from a designated place onboard vessel (Fire Control Station) and they must be kept in good working order and ready to use at all times with no exception.
All the outlet valves from the fuel oil and lubricating oil tanks, from which oil could flow to feed a fire, are equipped with hydraulically or pneumatically operated quick closing valves.
The quick-closing valves are closed by pulling on a handle which operates a piston in a hydraulic or pneumatic cylinder. The action of the piston is transmitted to the collapsing mechanism of the associated valve or valves, causing the valve to move to the closed position under the force of a spring.
In the video above, there is a test on a pneumatic controlled system, where the quick closing valves are activated by turning the three-way valve in the line to the valve actuators. This sends compressed air to the quick closing valve actuators which trips the valve causing it to close under the force of the spring.
After a valve has been tripped by means of the quick-closing device it must be reset locally. This is done by turning the hand wheel to close the valve, then turning the hand wheel in the opposite direction to reopen the valve. Before reopening the valve, the air supply line to the tripping mechanism must be vented and a check must be made to ensure that the collapsing mechanism is correctly repositioned.
The quick closing air reservoir is supplied with the compressed air from the control air system and the inlet valve to the reservoir should, under normal operating conditions, be locked in the open position. There is a drain valve on the air reservoir and this should be opened at regular intervals to remove any water which may be present.
In most cases a single hydraulic cylinder or pneumatic valve lever will operate a group of valves either on the same tank or on tanks which are located close together.
Diesel generator engines and sometimes main engine have their own quick-closing valve handles allowing individual diesel generator or main engines to be shut down, by closing the fuel inlet valve to the engine, should that be necessary. The emergency generator has a quick-closing valve on its fuel tank and this is closed by means of hydraulic cylinder handle, pneumatic valve or a wire link located outside the emergency generator room.
There are some tanks, such as some LO tanks, which are not equipped with quick closing valves as their valves are assumed to remain closed when the tank is not in use.
Operation of the quick-closing valve system should be tested at monthly intervals or in accordance with the company’s operating procedures to ensure that the valves function correctly. Operation of the quick-closing valves is essential to the safety of the vessel. Testing of the quick-closing valves should be carried out when the closing of the valves will not impede the operation of the vessel.
In addition to operating the quick closing valves, the air system also supplies the pneumatic cylinders which keep the engine room fan dampers and the funnel louvres in open position.
Fire dampers are fitted for air discharge from the engine room and they need to close the ventilation openings in the event of a fire in the engine room spaces. The dampers are kept open by air pressure supplied from the control air system. The dampers either have a counterweight attached to the damper linkage which ensures that the dampers close when the air pressure acting on the pneumatic cylinder is released, or are of the multi-blade type, whereby the dampers are linked and thus all close the damper when the air is vented from the cylinder.
In the case of the large fire flaps being fitted, the weight of the fire flap alone is sufficient to ensure closure and there is no need for additional counterweight.
All fire flaps may be closed locally by operation of a three-way vent valve to vent the pneumatic cylinder. If this vent valve is used to close the fire flap, the fire flap may be opened again by turning the valve back to the open position which allows an air supply to the operating cylinder. Vent valves are located, usually, at the port and starboard sides of the accommodation block on deck. They can also be operated through wire links and in this case the flap will close under its own weight once the wire has been unleashed from its normal resting position.
Fire flaps are also operated remotely by means of pushbuttons, levers or wire handles located in the fire control station (inside accommodation) and at the operating board situated outside the accommodation on deck.
Fire dampers should be tested at weekly intervals or in accordance with the company’s operating procedures to ensure that the dampers function and close correctly. Operation of the fire dampers is essential to the safety of the vessel and testing of should be carried out diligently and carefully independent of the vessel being at sea or in port.
In the event of a fire, it is important that any oil and air supply to the compartment on fire to be shut off and isolated. Thus all machinery that could constitute an addition to the fire must be electrically isolated as required and they comprises of all fuel pumps, hydraulic oil pumps, lubricating pumps, boiler, purifiers, ventilation supply and exhaust fans. The various emergency stops are grouped together for identification purpose, being coded on the switchboard where the group starters are situated (e.g ES1, ES2 etc.).
Emergency stops are available in order to stop the equipment, pumps and fans and to close valves in an emergency and they are provided in the fire station, on deck or at the engine room entrance. They must not be confused with the remote stops which are available for stopping some pumps when carrying out normal ship duties. For example, emergency stop pushbuttons are provided at the bunker stations for stopping the MDO and HFO transfer pumps or sludge pump, when using these pumps to pump oil or sludge ashore.
The emergency stop switches are located under a cover or inside a locked box in order to prevent accidental operation.
Usually, the emergency stops should be tested at 3 monthly interval or in accordance with the company’s operating procedures to ensure that the emergency stops work correctly. Operation of the emergency stops is essential to the safety of the vessel and testing of should be carried out diligently and carefully without impeding with vessel normal operations (emergency stops should not be tested during maneuverings as this can lead to vessel black out and accidents) .
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