The marine constant pressure unit is an integrated, pre-assembled marine system that combines multiple functions within a ship's central air conditioning circulating refrigerant (or heating) water system. These include heat exchange, chilled (or heated) water circulation, pressure regulation, air venting, make-up water supply, filtration, water treatment, and electrical control. The unit comprises heating heat exchange apparatus (plate heat exchanger), steam flow regulating valve assembly, steam trap assembly, constant pressure expansion diaphragm tank, automatic air venting device, differential pressure controller, make-up water isolation device, deionised water treatment unit, and electric/manual valves with control unit.

Marine pressure-regulating devices possess the following characteristics:

(1) Marine constant pressure devices represent an ideal replacement for closed-loop refrigerant (or heating medium) circulation systems within shipboard air conditioning installations. By eliminating the conventional elevated open expansion tank, they also resolve numerous disadvantages previously associated with positioning such tanks on upper decks or outside compartments.

(2) Automatic switching between cooling and heating modes; automated regulation of steam flow entering the heating unit; the exhaust system automatically purges free gases and dissolved gases from the circulating water within the system. This resolves the longstanding issues within naval air conditioning systems caused by gases in the circulating water, such as air locks, corrosion, and energy losses. Concurrently, it effectively prevents pump cavitation, thereby reducing maintenance requirements and extending the operational lifespan of the equipment.

(3) The constant pressure setting for the circulating water system may be adjusted at any time to meet the requirements of the ship's air conditioning system, with high pressure regulation accuracy (±0.1 bar);

(4) Automatic water replenishment may occur based on pressure reduction relative to the system set point;

(5) The control system displays the actual operating parameters of the system and features automatic alarms for delayed water replenishment and audible/visual alerts for equipment malfunctions.

(6) The unit features a compact structure, light weight and ease of maintenance. Once installed, it requires only the connection of relevant pipelines to the unit before commissioning and operation can commence, thereby reducing on-site installation workload and shortening the construction period.

(7) The unit may be adapted, modified, or reconfigured in terms of its functions and components to suit the scale and configuration characteristics of various shipboard air-conditioning systems. It may also be adjusted or split in terms of its external form and layout to accommodate the equipment arrangement within the installation compartment.