Fit for purpose
Published: 02 July, 2014
ODEE spoke with Ned Trigg, senior vice president global marine sales at Dometic Marine, about the importance of providing a fully rounded design, installation and service package for customers of HVAC and related equipment early in the offshore supply vessel design process.
The marine solutions marketplace in general is truly global. A vessel could be built in China and spend its operational life in the European North Sea. Therefore, a heating, ventilation and air conditioning solutions provider needs to be able to offer a global network of design, installation and servicing partners that are fully conversant with HVAC products and the bespoke requirements of customers. This is the view of Dometic Marine’s senior vice president global marine sales, Ned Trigg. “The provision of a complete service package has been the mainstay of our success over the decades,” he reflected. “In the commercial sector, which includes offshore supply vessels, a lot of the work we carry out is done by systems integrator partners. This is because the builders of these vessels want full turnkey solutions; they want our team to be able to come to the yard and undertake the complete installation of the HVAC equipment, not just supply everything to site.”
Over the years Dometic Marine has evolved a successful formula whereby its agents are able to provide the required type of design, installation and service package required by architects and end customers.
The right calculations
Trigg explained that at the start of any building project Dometic Marine and its partners normally begin with the design of a vessel, either on paper on a computer. “Once the basic design has been completed we then consider all the necessary calculations,” he pointed out. “The architect or end-user sends us the plan drawings and we make the load calculations to determine the HVAC system’s capacity requirements for each zone on the vessel. At this stage there could be a number of options in terms of how much redundancy and backup is needed on each system, and whether the customer wants independent controls for each separate cabin. So we normally work hand-in-hand with the architect to come up with a design that perfectly fits the customer’s specifications.”
Of course, it is critical to know where the vessel will operate. Therefore, Dometic Marine puts together a detailed equipment list that takes into consideration all the operational and environment conditions that are to be expected during the life of the vessel and the equipment it carries. “For example, because air conditioning involves such a large electrical load the architect must discuss in detail all the power requirements with generator suppliers in order to determine what size generator will be needed to support the equipment on the vessel,” explained Trigg. “We can then customise the chiller and air conditioning package so it can fit the required orientation in as optimal a fashion as possible, given the dimensions of the vessel. Our team can then go to the yard and work with the installers to verify the docking of the air handlers and make sure the return air grills etc. are to the right specification.”
Solution sampler
In terms of the type of specific equipment Dometic Marine can supply to the offshore oil & gas market, the company’s recently launched Durasea range of 36,000 – 120,000 BTU/hr air-cooled condensers are suitable for the operations of both supply vessels and platforms. The air conditioning condensing units are designed for durability in harsh nautical applications, offering long service life, reliable performance and energy efficiency.
“The DuraSea’s cabinet is constructed of stainless steel 304, which can resist heavy salt-spray and also provide UV protection,” said Trigg. “Designed for deck or rooftop mounting, the optional risers elevate the unit above the mounting surface to provide effective water drainage and protect the coil from debris and salt water. To further fortify the unit from severe marine conditions, corrosion-resistant stainless-steel fasteners are used, and all other external components have a protective coating. The control box and compressor are strategically located within the cabinet for easy service access and for extra protection against corrosion.”
Trigg added that Dometic’s designers have taken steps to eliminate puddling on the top of the units by angling the surface to all 4 sides for fast drainage. The permanently lubricated fan motor has IP 54, or better, protection and drives a vertically mounted composite fan, which has been designed to eliminate rust problems often experienced when used in the continuous operation experienced in the offshore environment.
High efficiency copper tube and aluminium fin coil with dipped coating has been tested to exceed 6000 hours of continuous usage. “This exhaustive salt spray test ensures the Durasea will operate trouble free throughout extended periods of operation whatever the conditions experienced,” said Trigg.
All DuraSea units employ hermetically sealed scroll compressors with internal overload protection, the latest in high-efficiency, reliable compressor technology. They reduce noise and vibration, and have a higher tolerance of liquid refrigerant and system contaminants. Scroll compressors also feature low start torque to minimise the starting-current spike that occurs with old-technology compressors. Units are available in 410A refrigerant or 417A refrigerant for retrofit of existing systems. The new 7.5- and 10-ton sizes offer a compact footprint in an ‘industrial’-styled equipment design that includes forklift slots and lifting eyes.
Modular design
Trigg explained that when it comes to chilled water project work most of what Dometic Marine provides is to a modular design. He added that Dometic Marine also ensures all solutions supplied are easily serviceable, allowing easy maintenance procedures to take place as and when required. “Ultimately, it all comes down to satisfying the customer’s needs as accurately as possible,” concluded Trigg.
