A Step guide to the PSM System

Approval certification

 

System overview

Water Detecting Sensor options

Siting of the sensors.

Principle of operation

Central Monitor/Alarm Station.

Mounting considerations for Central Monitor

For use in Hazardous Zones

Holds used for seawater ballast purposes.

Factory Configured – simple installation

Full support – Future proof

PSM Engineers can assist

Installation considerations

Bulkhead Penetration

Cabling

Installation drawings

 

editorial

 

Questionnaire form 

 

The individual elements and components that comprise the PSM system are as follows. The quantity of individual components may be selected to suit the actual vessel. To assist in cost preparation a component breakdown sheet is attached from which, a full system cost can be readily calculated. A questionnaire form is attached for use by specifiers and customers. Simply fill in the requested data and return to our Sales Engineering dept. for an instant quotation. Also for quick reference purposes a brief guide to the regulation indicates the designation of various holds and spaces. However, this is a guide only and is not the definitive regulation. Purchasers should refer to the relevant Standards and Bodies to satisfy themselves of compliance.

W.I.A.S. Sensors

The Series 260 sensor body is all 316 stainless steel with a sensing diaphragm in Hastelloy C276 for corrosion resistance. The sensor was designed from the outset for arduous shipboard application and features unrivalled tolerance to shock, overload, and extremes of application conditions. All active electronics are housed remotely in the amplifier module which is itself contained within the deck mounted termination enclosure. The Deck enclosure also contains a simple test mechanism for the sensor. A small hand operated pump is used to temporarily simulate an applied pressure and cause the sensors output to rise to alarm levels. There are no additional pressure lines required for this function as this is carried within the sensor cable, there is no possibility of damaging the sensor by over pressuring and the sensor will automatically reset a few seconds after the pump is operated.

The Hydrostatic sensor outputs a 4-20mA signal in relation to actual liquid level, this means that only one sensor is needed to detect both Pre and Main alarm conditions.

Under dry conditions the hydrostatic sensor outputs a continuous signal of 4mA.  In the event that there is water ingress into the hold the sensor output will rise.  The central display panel constantly monitors the sensors output signal.  If the water level rises beyond the permitted limits (usually 500mm for pre-alarm) it will provide an immediate visual and audible annunciation.  If the water level continues to rise, a further main alarm will be provided. 

The central WIAS monitor features dedicated lamps and a multi-tone audible alarm (different tones distinguish pre-alarm and main alarm conditions) for reporting of the alarm conditions. The current status of all sensors is displayed on a backlit LCD display. Individual alarms are clearly identified and may be acknowledged.

Where the cargo hold or deck is classified a Hazardous Zone, Zener barriers are incorporated into the central monitor to provide an Intrinsically Safe installation.

The Bulksafe W.I.A.S. system is factory configured in accordance with a questionnaire (copy attached) which should be completed by the user for each installation. Installation and commissioning of the system is straightforward an requires no specialist knowledge and may be undertaken by Shipyard personnel or Riding squads whilst the Ship is underway.

WIS Sensors are designed to provide complete simplicity and flexibility on retrofit and new builds. Adaptors are provided so they may be clamped in the holds, secured onto pole or pipe ends, or inserted into a “Still” tube enabling later removal without entering the hold, tank or void space. If a still pipe is used then a separate (PSM supplied) filter assembly may also be employed. Whereas the filter is not necessary for operation it is recommended as it will significantly reduce the need for any routine cleaning of the sensors, as the cargo has no way of coming directly into contact with them. The filter itself is designed for simple cleaning / flushing, either from within the hold or by back-flushing via the still pipe.

Typically, the central monitor should be located in a continuously manned area (e.g. Navigation bridge) where this is not possible or additional displays are required, an optional repeater panel may be provided. These repeater panel(s) communicate with the central monitor via a single screened twisted pair cable using an RS485 link and multiple repeaters can be daisy chained. The repeaters can be for display only, or may be enabled for alarm acknowledgement.

Each sensor is pre-fitted with a specified length of cable to allow termination in the Deck enclosure.

The 4-20mA signal from each sensor requires a 2 core cable which is run back from each deck enclosure to the central monitor.

Optionally, a marshalling enclosure may be provided which enables all cabling from the deck to be combined in a single multi-core that runs to the Main display on the Bridge. This marshalling enclosure will normally be located in the accommodation block.