GB2413387A

GB2413387A - A bilge alarm which utilises a pressure sensing device

Info

Publication number: GB2413387A
Application number: GB0408924A
Authority: GB
Inventors: Francis West; Ian Mitchell
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-04-22
Filing date: 2004-04-22
Publication date: 2005-10-26
Also published as: GB0408924D0

Abstract

A bilge alarm which utilises a pressure sensing device A, the device being located in the bilge B, and is connected to a local display/alarm panel C. Upon the average level of the bilge water reaching a predetermined height D, an audible and visual alarm is activated at the local display panel C. This first height is called the normal pump level D, the alarm alerting the user to activate the bilge pump to lower the bilge water level. If the bilge water continues to rise, upon the average level of the bilge water reaching a second higher predetermined height E, a second separate audible and visual alarm id activated at the local display panel C. This second height is called the urgent pump level E. The alarm will also be activated upon the detection of a wiring fault in the cable to the sensor, or a completely dead sensor.

Description

1 24 13387 Bilge alarm IJK fishing vessels are seen to be sinking at an

alarming rate, a major factor being undetected flooding.

Classical bilge alarms work by a float switch: water rises, activating a switch, which closes a circuit causing an audible and /or visual alarm.

Once flooding starts, it only accelerates, because of the ever increasing head of water. Early warning is critical to take prompt action to stem the leak, or provide timely pumping to avoiding irrversable flooding: once a ship engine stops due to flooding, almost all power is lost for pumps, and the vessel will frequently be lost, along with crews lives.

the problems with float switch bilge alarm systems are as follows: 1: as the vessel rolls, the bilge water splashes up, causing false alarms, which leads the crew to switch off the alarm system.

2: the float switches are located in the bilge, and are very inconvenient to test, leading to testing of the bilge alarm system rarely being done.

3:float switches get stuck /jammed in the on position, so the alarm activates continually.

4: float switches get stuck in the off position, leading to an undetected, non functioning alarm system.

5:wires get damaged, so the float switch activation is not recognised by the alarm system, unless tested and detected manually 6: switches corode in the presence of seawater, hydraulic fluid, and chemicals normally found in bilges, rendering them useless.

7:the alarm panels have switches that are easily changed without realising, when coming into contact with them. This can lead to the system being disabled' or partly shut down.

8:alarms get disabled when the crew are about to take action that they know will cause an increased bilge level, and they are short handed to pump the bilge at that time.

9:if a flood occurs while the vessel is unmanned, even with an operational alarm system, the flood is still undetected.

any one of the above scenarios could lead to a controllable flood going undetected, leading to damage or loss of the vessel and lives.

The object ofthe invention is to provide a bilge monitor and alarm system that overcomes the problems of float switch type systems, and helps enforce good working practices.

One specific embodiment of the invention is described here with reference to the drawings, in which a pressure sensor (figl-a) is secured in the bilge (figl-b). and is connected to a local display/alarm panel (figl-c) which performs the necessary information processing, averaging, and decision making.

Upon the average level of the bilge water reaching a predetermined height programmed into the local display/alarm panel, an audible and visual alarm (fig2-b)is activated at the local display/alarm panel. . This first height is called the NORMAI, PUMP LEVEL( fig 1-d). The alarm may be silenced for a period of time by actioning a switch on the display/alarm panel(fig2-c) to allow time to facilitate the pumping of the bilge water, if the average bilge water level is still above the Normal Pump Level after the period of time, the alarm recurrs, giving warning that the action taken has not been effective in lowering the bilge water level, and further action is required.

If the bilge water level continues to rise, upon the average level of the bilge water reaching a second, higher predetermined height, a second separate audible and visual alarm is activated at a local alarm panel (fig2-d). This height is called the URGENT PUMP LEVEL (figl-e) The alarm may be again be silenced for a period of time to facilitate the pumping of the bilge water. If the average bilge water level is still above the Urgent Pump Level after the period of time, the alarm recurrs, giving warning that the action taken has not been effective in lowering the bilge water level, and further action is required.

The invention has the facility to have repeater display/alarm panels (see figure 3) located at various point in the vessel, typically a repeater would be on the bridge, and the local alarm located in the engine room, or other compartment to be monitored. (see figure 3) The repeater display/alarm panel is connected to the local display /alarm panel.

The repeater is designed such that the Normal Pump condition can be cancelled from its location, but an Urgent Pump condition could only be cancelled from the local alarm panel, located in the compartment concerned, forcing a manned inspection of the affected compartment.

The local display/alarm panel of the invention continually tests its connecting cable to the pressure sensor, and the pressure sensor. Because of the current output characteristics of the pressure sensor, the invention can detect an open circuit cable, or short circuit cable. Similarly, the invention detects the change in the characteristics of the sensor when it is faulty.

The repeater display/alarm panel ( if utilised) of the invention shnilarly detects the faults communicated to it from the local display/alarm panel, and also any non communication from the local display/alarm panel. If a fault is detected anywhere on the invention, it raises a seperate, identifiable alarm condition.

The panel construction may be of metal, or plastic or other suitable durable material, encasing the power supply, and electronics. Electrical connection to the panel is by suitably splash proof connector or cable entry gland depending on the aesthetic and environmental requirements. (fig2-a) Each alarm condition is visually shown by the lighting an LED or lamp, and audibly by a sounder.

Its powered condition is also indicated by a LED/lamp (fig2-e) The alarm acknowledgement switch on the panel requires to be pressed for an extended period typically at least 1 second to take effect, negating accidental pushes.

Claims

Claims 1: A monitor panel continually measuring the level of fluid in a

bilge, generating visual and audible alarms upon the fluid level reaching a predetermined height and detected wiring faults; connected to the monitor panel is the sensor used to detect the fluid level, which has an electrical current output dependent upon the height of fluid above it, has a non zero minimum current output, and a limited maximum current output, and a pressure equalization tube incorporated into the connecting cable. 2:

A monitor as in claim 1, where a second unique alarm is generated by a second level of fluid being detected. 3:

The monitor as in claims 1 has a switch which may be deliberately activated for a finite time to acknowledge and suspend the alarm as in claims 1 and 2 for a period of time. 4:

The alarms in claims 1 and 3 recurs after a finite time of continued alarm level detection. 5:

the monitor described in claim1 detects an open circuit in the wiring between the sensor and the monitor panel by the absence of electrical current, and generates an alarm as in claim1 6: the monitor described in claim1 detects a short circuit in the wiring between the sensor and the monitor panel and limits the electrical current to a level above that maximum limit in claim1, and generates an alarm as in claim1 7: the monitor described in claim1 can be manually tested by means of a 3 position switch located in a dry location close to the sensor, the switch wired to give normal operation, open circuit condition, and short circuit condition; to test the wiring, the switch would be changed to the short circuit position, and should generate an alarm as in claim1, and to the open circuit position, which should also generate an alarm as in claim1, 8: the sensor as described in claim 1 can be tested by causing a vacuum in the pressure equalization tube, by means of attaching a vacuum forming device to the tube, and generate an alarm as in claim1 r. in.

the manual testing switch as in claim 7, and the pressure equalization tube as in claim 8, may be located in a non airtight housing along with a vacuum inducing device, where cable termination for extending said cables to the monitor panel are made via an electrical terminal block, also connected to the switch as in claim7 Amendments to the claims have been filed as follows 1: A monitor panel continually measuring the level of fluid in a bilge, generating visual and audible alarms upon the fluid level reaching a predetermined height, exceeding a predetermined rate of increase in height, and detected wiring faults; connected to the monitor panel is the sensor used to detect the fluid level, which has an electrical current output dependent upon the height of fluid above it, has a non zero minimum current output, and a limited maximum current output, and a pressure equalization tube incorporated into the connecting cable. 2:

A monitor as in claim 1, where a second unique alarm is generated by a second level of fluid being detected, or exceeding a predetermined rate of increase in height, 3: The monitor as in claims 1 has a switch which may be deliberately, not accidentally activated for a finite time to acknowledge and suspend the alarm as in claims 1 and 2 for a period of time. 4:

The alarms in claims 1 and 3 recurs after a finite time of continued alarm level detection. 5:

the monitor described in claim1 detects an open circuit In the wiring between the sensor and the monitor panel by the absence of electrical current, and generates an alarm as in claim1 6: the monitor described in claim1 detects a short circuit in the wiring between the sensor and the monitor panel and limits the electrical current to a level above that maximum limit in claim1, and generates an alarm as in claim1 7: the monitor described in claim1 can be manually tested by means of a 3 position switch located in a dry location close to tine sensor, the switch veered to give normal operation, open circuit condition, and short circuit condition, to test the wiring, the switch would be changed to the short circuit position, and should generate an alarm as in claim1, and to the open circuit position, which should also generate an alarm as in claim1, 8: the sensor as described in claim 1 can be tested by causing a vacuum in the pressure equalization tube, by means of attaching a vacuum forming device to the tube, and generate an alarm as in claim1 9: the manual testing switch as in claim 7, and the pressure equalization tube as in claim 8, may be located in a non airtight housing along with a vacuum inducing device, where cable termination for extending said cables to the monitor panel are made via an electrical terminal block, also connected to the switch as in claim7