Historically, valve manufacturers have performed accredited witness flow testing for relief valves at third-party facilities. Testing is a costly process and is usually carried out over the course of a week. The test program is pre-agreed and allows little scope for development changes whilst testing is underway, nor the ability to test every valve with a combination of a gauze, bursting disc or cowl. Furthermore, there are very few facilities around the world able to test at the required flow rates.
For these reasons, Fort Vale made a significant financial investment in a purpose-built Test Laboratory at its U.K. headquarters. Their gas flow rig is designed to BSEN4126 and ASME VIII Div.1 and is approved and certified by Lloyds Register. Devised to test relief valves with a maximum flow rate of 6.1 Nm3/s at 5.28 Bar, it has allowed the company to accurately and quickly assess any combination of relief valve and ancillary item that may affect flow, within the limitations of the test rig. Fort Vale believes that this is an unrivalled facility that allows them to make a unique contribution to the universal safety of tank containers.
As part of their Continual Development program, Fort Vale conducted a detailed analysis of the operation and flow characteristics of its entire range of relief valves. This is believed to be the most comprehensive study ever undertaken on valves and systems for intermodal tanks and has brought about an enhanced practical understanding of valve operating conditions, particularly with regard to de-ration factors for ancillary parts, such as gauzes and burst discs.
When a tank builder is determining a relief valve flow requirement, the calculation is based upon a valve fitted with a burst disc and gauze to allow for maximum de-ration, even if no ancillary parts will be fitted eventually. Witness testing has proved that the flow rate of an 80mm Hyper Maxi relief valve, both with and without de-ration factors, meets current regulatory requirements and, at the time of going to press, exceeds all current published comparative flow rates of relief valves by other manufacturers.
The Hyper Maxi series of 80mm relief valves will offer a range of pressure settings from 3 PSI up to 204 PSI (0.21 Bar to 14.07 Bar) and vacuum settings from 0.5”Hg to 24”Hg (0.02 Bar to 0.81 Bar). There are 3 body styles; standard, short extended and long extended, each with a slotted flange to facilitate 4 common drilling patterns.
The valve body and port geometry has been optimized and now incorporates a “lift stop”, which is subject to a patent application and which enables the valve’s pressure plate lift to be precisely controlled. This reduces turbulence and improves the valve’s performance which means that the flow rate of the valve remains accurate and consistent – a fact which has been proved by repeated testing.
Fort Vale reports that, whilst the new 80mm flanged Hyper Maxi will be phased in to replace their existing 80mm Super Maxi model, the supply of the current range of 65mm bore and 65-80mm tapered bore Super Maxi valves will continue. It is planned to incorporate the “lift stop” safety feature across Fort Vale’s range of relief valves and this process has already started with the 65mm Super Maxi range.
Because of the design changes, some of the components are not interchangeable between the existing 80mm Super Maxi and the new 80mm Hyper Maxi. However, Fort Vale states that they will continue to supply spare parts and world-wide after-market service and support for the Super Maxi indefinitely.
Fort Vale regularly stresses the importance of using only genuine spare parts, ancillaries and consumables, available through its authorised worldwide distribution network. “To accept substitute or “copy” components is not merely false economy. This practice invalidates product warranty and jeopardises the safety and performance characteristics of both the Fort Vale product and the vessel to which it is fitted,” comments the company. “Our test data corroborates that customers will experience significantly reduced flow rates and greater de-rations when non-genuine components, such as springs, or alternative ancillaries, such as gauzes, are used in conjunction with a Fort Vale relief valve.”
The new Hyper Maxi relief valve will be available to order from 1st November 2015. For more detailed information on flow rates and de-rations relating to this valve and associated components.
November 12, 2015