Tank Storage Magazine v03 i02

40.00

Volume: 3
Issue: 2
Date Published: June 1, 2007

Category:

Headlines

STOCEXPO REVIEW: Reviewing the latest StocExpo Europe event in Antwerp 20-22 March.

With a slightly southward change of location and an upward change of size, March saw StocExpo 2007 go to the charming Belgian city of Antwerp for three packed days. Home to Europe’s largest chemical cluster, Antwerp was a superb choice for the third StocExpo Europe. The event saw an exceptionally high rate of returnees in terms of exhibitors, visitors and conference delegates, and an impressive number of new faces, companies and nationalities. StocExpo 2007 saw conference delegate numbers hitting a record 250, and the show generating 1,800 visitors. The range of countries of origin and nationalities of attendees – 78 in total – is proof that StocExpo has become the bulk liquid storage market’s event of choice, offering a great opportunity to meet existing and new customers and suppliers, debate the big issues driving the sector, display and demonstrate new products and services and, crucially, network. With people travelling to Antwerp from as far afield as Australia, Brazil, Saudi Arabia and Serbia, StocExpo Europe has quickly become more of a melting pot than an enormous Belgian chocolate fondue, and everyone’s dipping in. More positive contacts were made during this show than at any other time, with quite a few companies managing to get deals signed on the spot. One company which experienced particular success was UK-based tank equipment designer and manufacturer Emco Wheaton. The company is still busy contacting potential customers, having made 64 firm leads from the event. France-based vapour recovery supplier CarboVac experienced similar results. The company says it gained good business opportunities and definitely sees StocExpo as a meeting point between itself and its international agents and customers. ‘It is very important that we participate,’ says Guillaume Heurteloup, commercial engineer at CarboVac, who hopes that a future StocExpo will be held in Latin America. The quality of the visitors to StocExpo pleased a majority of the exhibitors so much so that over 50% of the present exhibitors have signed up for StocExpo Europe 2008. So with its increased floor plan, it is looking to be another sell-out show. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


FRENZY HITS STORAGE CONSTRUCTION IN US

While corrosion, emissions, leaks and spills continue to be major challenges in the bulk liquid storage industry in the US, 2007 is still turning into a big year for consolidation and expansion. Possibly bolstered by uncertainty in the oil sector – as storage is central to reducing price volatility and to smoothing seasonal and other demand variations – there has been some major interest from investors. Working in the industry’s favour as well, was the gradual introduction of low-sulphur petroleum and diesel products. These required additional capacity at many terminals and offered some companies the opportunity to provide extra services connected with distributing this new fuel. Where financial reports are available, 2006 appears to have been a good year for those with terminals and distribution facilities and they have continued into 2007. Magellan Midstream Partners, with its 45 terminals and seven marine facilities, showed an increase in operating profits of 43%, while Plains All American Pipeline recorded a facilities segment profit increase approaching 400%. Earnings at the Norwegian owned Odfjell Terminals’ Houston facility were $22 million (€16.3 million) in 2006, up from the previous year’s $17 million. It is this profitability, perhaps, that has fuelled a number of company takeovers, mergers and splits. Last year Valero LP and Valero GP were hived off from Valero Energy Corporation to become NuStar Energy with a rebranded image and entry on the New York Stock Exchange; and in April, LBC Tank Terminals announced that, subject to regulatory approval, ownership from One Equity Partners LLC, the private equity arm of JP Morgan Chase would be transferred to Australia’s Challenge Infrastructure Fund (CIF). The current construction frenzy is illustrated by happenings at Plains All American Pipelines (Plains), where even before the commissioning of Phase I at its St James Terminal in Louisiana, a second phase expansion project was announced. Begun in mid-2005, it became operational in March this year, with seven crude oil storage tanks and an interconnecting piping system. The capacity of phase I is 3.5 million barrels, and it was delivered at a cost of approximately $93 million. Matrix Service of Tulsa has been re-appointed as contractor for phase II, which will see the terminal expand to 6.2 million barrels costingS $64 million, and is scheduled to become available for use during the Q1 of 2008. Greg Armstrong, chairman and CEO of the partnership, said that the investment decision was based on a belief that foreign imports would continue to increase as a result of increased US crude oil consumption and falling domestic production. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


HOUSTON PREPARES FOR ILTA

The 27th International Liquid Terminals Association (ILTA) Operating Conference and Trade Show will take place in Houston, Texas from 11-13th June 2007. Over 220 companies exhibit at the show each year, providing the terminal industry with information about the latest technologies around, while the simultaneously run conference provides insider knowledge on the industry’s hottest issues. With all the hype surrounding biofuels within the terminal industry, ILTA has added a new track this year, on renewable fuels. This set of presentations will examine the rapidly expanding market, and will examine storage, handling and blending strategies. The featured speaker for the event is a partner in a law firm, who is also discussing the investment boom in downstream assets and renewable fuels. The talk will address the prospects for the continued flow of fresh capital into the biofuels industry. A range of other issues will also be covered at the event, such as the operation of floating roofs, environmental health and safety, industry updates and management issues. A series of other workshops will also tackle tank air emissions and safe tank entry. The list of exhibitors for the trade show is almost as impressive as those at Europe’s StocExpo in March. From automation to vapour control, and from aluminium roofs to vents and valves, the whole range of technology used in the tank storage sector will be showcased. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


GROWING WITH THE TIMES

The 27th International Liquid Terminals Association (ILTA) Operating Conference and Trade Show will take place in Houston, Texas from 11-13th June 2007. Over 220 companies exhibit at the show each year, providing the terminal industry with information about the latest technologies around, while the simultaneously run conference provides insider knowledge on the industry’s hottest issues. With all the hype surrounding biofuels within the terminal industry, ILTA has added a new track this year, on renewable fuels. This set of presentations will examine the rapidly expanding market, and will examine storage, handling and blending strategies. The featured speaker for the event is a partner in a law firm, who is also discussing the investment boom in downstream assets and renewable fuels. The talk will address the prospects for the continued flow of fresh capital into the biofuels industry. A range of other issues will also be covered at the event, such as the operation of floating roofs, environmental healthUS-based Westway Terminals has big plans for 2007 and beyond. Westway Terminals is one of the premier providers of bulk liquid storage, and as such owns 29 storage sites worldwide. With roots going back to 1940, the company focuses on niche markets such as chemicals and commodities. The main products it handles are agricultural liquids and specialty chemicals, rather than the more traditional storage liquids such as petroleum or gasoline. But company president Wayne Driggers is not adverse to new products. He has been with the company since 1991, and has been in his current role for five years. ‘We’re always looking at new opportunities, and we look at new products every day,’ he explains. According to Driggers, Westway has spent the past 15 years expanding, and it certainly doesn’t intend to stop now. The company has 15 sites in the US, 12 in Europe, one in Mozambique and one in South Korea. Its global storage capacity is approximately 400 million gallons, and its customers are most of the top 20 chemical manufacturers and distributors, major oil companies and major agricultural companies. The 1950s and 1960s were periods of rapid expansion for the company. Westway established numerous bulk liquid terminals on the inland rivers, the Great Lakes, and important rail locations, which greatly expanded its terminal network. In the 1970’s and 1980’s Westway diversified its terminal operations to include the storage and handling of many other bulk liquid commodities. The company is now carrying out the largest expansion in its history at its site in Houston. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


PREVENTION IS ALWAYS BETTER THAN A CURE

In an industry as potentially dangerous as fuel storage, health and safety needs to be more than just a message on the noticeboard. Earlier this year, international oil giant BP was castigated by US safety investigators over its Texas City plant explosion, which killed 15 workers in 2005. According to the draft report from the US Chemical Safety Board, the blast was the result of lax safety culture at BP. Fortunately, explosions on this scale are rare, but the recent report highlights that when safety is compromised on any plant or tank terminal, lives are at risk. Explosion and fire safety equipment in tank terminals is often bespoke to the site to avoid any potential misapplication. Regulations, such as the European Union’s ATEX directive, have created a framework for controlling explosive atmospheres and the standards of equipment and protective systems used in them. The ATEX directive was designed to open up free trade across Europe, and align technical and legal requirements across member states for equipment and protective systems used in potentially explosive atmospheres. Since July 2003 it has been mandatory for all electrical and mechanical equipment used in potentially explosive atmospheres to be compliant with the ATEX 94/9/EC directive. The burden also falls on the end-user with a second ATEX directive 1999/92/EC and its requirement to assess an area for explosion risk. Previously there had been no obligation to use certified equipment or to grade an area as potentially explosive. In the US, there is a system of class standards, and within those are divisions. ATEX zone one will roughly translate as US class one division one, but certification with one standard does not imply reciprocal certification. Site managers at tank terminals protect storage tanks from implosion or explosion using a variety of measures. Thermal combustion units in chemical, pharmaceutical and petrochemical plants use burner systems for thermal waste disposal to reduce emissions. The problem with using premixing burner units is that they require highly flammable fuel and oxidant gases to be mixed in confined chambers before they are burned. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


LASTFIRE UPDATE

Approximately 12 years ago, recognising the need to have validated data on the risks associated with fires in large, open top floating roof storage tanks, 16 oil companies joined together to form a project group to thoroughly investigate the issue. The project was known as Lastfire - Large Atmospheric Storage Tank Fires. The project was initiated due to the oil and petrochemical industries’ recognition that the fire hazards associated with such tanks, although known to be relatively low, were insufficiently understood to be able to develop fully justified site specific fire response and risk reduction policies. Open top floating roof tanks, introduced to reduce evaporative losses of product to atmosphere, had always been recognised within the industry as having a relatively good fire incident record when compared to other types of facility. However, the associated risk had not been sufficiently quantified. It was also recognised that when a major incident occurred, such as a full surface fire due to ignition when the floating roof had sunk, control measures, mechanisms for incident escalation and consequential potential damage to life safety, the environment, business interruption and asset value were largely misunderstood. When such major incidents, albeit infrequent, occur, media interest is high and consequently there is considerable pressure on tank operators to demonstrate that they are taking all reasonable measures to minimise risk. In many cases there has been insufficient data to determine whether some risk reduction measures were truly effective or justified. Often the only information available was from organisations with a strong commercial interest in promoting one particular product or service. It had thus been difficult for operators and legislative or statutory authorities to base risk reduction requirements on credible scenarios or proven effectiveness of mitigation measures. When this situation was coupled with a general international recognition that prescriptive standards for fire protection were not always appropriate, it is clear there was a need to investigate, in depth, the fire risk associated with such facilities. A true Fire Hazard Management (FHM) approach to reducing fire associated risk to as low as is reasonably practicable was adopted during the project. This was in line with international regulatory trends towards preparation of safety cases whereby all aspects of risk mitigation including incident prevention are reviewed. Previously, fire hazard management has tended to be very prescriptive and concentrated on fire fighting measures rather than incident prevention. As risk is defined as the product of incident probability and incident consequence, it is as important to reduce incident frequency as it is to minimise or mitigate potential incident consequences. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


SHUNTS CAN TRIGGER FIRES

Companies from BP and Shell to ExxonMobil and ConocoPhilips are adopting a new grounding technology known as Retractable Grounding Assembly. Floating Roof Tank (FRT) shunts are far from the safe conductors of stray electrical energy they are intended to be and can, in fact, trigger tank fires. Recent tests conducted for the American Petroleum Institute (API) RP 545 Lightning Protection for Above Ground Storage Tanks task group have shown that shunts can generate showers of sparks during lighting strikes, according to a bulletin of the task group. If there is a gap between the seal and the tank wall during a lightning strike and if a flammable mixture is present, a tank fire may result, continues the bulletin. Despite the widespread use of shunts, hundreds of tank fires occur each year worldwide. Recently in Minatitlan, Veracruz, Mexico, a lightning strike ignited a tank containing 55,000 barrels of petrol. Fearing the fire would spread to other tanks in the facility led authorities to evacuate an entire neighbourhood until the fire was extinguished. In New Orleans, a lightning strike ignited a tank holding 200,000 barrels of gas recently. Fire officials stated the blaze began in the seal of the tank, requiring local responders and company fire crews to bring the fire under control. Independent third-party testing, performed in cooperation with the API and the Energy Institute in the UK, has shown that arcing will occur at the shunt-shell interface under all lightning conditions, whether or not the shunts are above the roof or submerged. If the shunts are above the roof, however, arcing occurs in the worst possible place: in a Class I Division I hazardous area, which may have a highly ignitable concentration of fuel-air vapour. Floating installations are more susceptible to unintended sparking and fire than other oil and gas facilities due to their flash points being reached more easily. The severity of fires and explosions in FRTs, the difficulty of fighting those fires, and the risk of the loss of the entire facility have upped the urgency of establishing a reliable means of bonding the tank roof and shell. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


VALVE ACTUATORS - VITAL ELEMENTS FOR FIREPROOFING AND OVERALL PLANT SAFETY

In any oil and gas installation the requirement for safety is paramount and recent accidents at refinery and tank farm sites offer vivid illustrations of the catastrophic consequences of such events. Valve actuators have an important impact on safety as vital components for the movement and isolation of bulk liquids, providing not only the muscle to open and close the valves but also the brains to communicate their activities and operating condition. The advent of digital communication technology has dramatically enhanced the functionality of modern actuators whilst a long history of development in the oil and gas industry environment has produced a comprehensive range of designs and technologies to meet isolating, modulating, failsafe and ESD (emergency shut down) duties. Valve actuation company Rotork has extensive experience of tank farm installations. In the early 1960s Rotork began to develop design features in its electric actuators that have become benchmark industry standards. Probably the most significant is O ring double-sealing, born out of the environmental challenges of east Asia, where the practice of fitting breathers and drains to explosionproof equipment caused problems with condensation leading to breakdowns and high maintenance costs with traditionally designed actuators. Rotork’s solution was to adopt circular spigoted flamepaths as an alternative to the customary flat flanges and fit them with O rings to provide environmental sealing. The result was the first electric actuator designto feature an explosionproof and watertight enclosure. The double-sealing aspect of the design concerned the terminal compartment, where covers could be removed for days on site whilst wiring up was in progress, once again leaving the internal electrics vulnerable to the elements. Double-sealing prevented this through the introduction of a separately O ring sealed terminal bung. As a result, when the terminal cover was removed any ingress of water or condensation could not reach any part of the actuator’s internal electrical parts. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


RECENT ADVANCES IN AUTOMATED OVERFILL PROTECTION AND INVENTORY MONITORING

The entire industrialised world is undergoing a profound technology revolution which is dramatically benefiting the tank storage industry. Never before have the demands for improved safety, environmental protection, and enhanced supply chain management been greater. It is indeed fortunate that recent and ongoing meteoric advances in three specific technologies have brought new and innovative solutions to our industry in such a timely manner. In the field of industrial automation, few breakthroughs have caused such intense product innovation as those brought about by spread spectrum wireless and lithium ion primary batteries. These have led to the development of ground-breaking new automation products in virtually every industrial discipline. Another technology, magnetostrictive sensing, has also undergone a relatively recent revitalisation, which has allowed for even greater benefits to be realised as it now permits extremely highaccuracy yet power-efficient level measurement in the tall AST’s common to our industry. Suitability of wireless systems Many in the industry have attempted, usually with dubious results, to employ various off-the-shelf industrial radio systems to transmit tank sensor data back to control points. Certainly, the benefits of reliable wireless telemetry are obvious to anyone who has purchased, installed, and maintained conventional hard-wired storage tank monitoring systems. Unfortunately, most industrial wireless telemetry systems are not well-suited for storage tank applications. Many have suffered the frustrations of attempting to use the wrong radio technologies for this extremely challenging application. Most of these commercially available industrial wireless systems are optimised for continuously transmitting huge quantities of data at high speed over rather long distances (>5 km), and generally require line-of-sight between the transmitter and receiver. This is certainly not the scenario required for storage tank monitoring. Companies need only transmit very small packets of data over relative short distances (<5 km; but rarely have the luxury of lineof- sight telemetry. High bandwidth and speed are not particularly advantageous, but data redundancy and robustness are absolutely essential to achieving the required reliability. Tank overfill protection is considered an extremely critical function wherein the failure of proper alarm enunciation can be life threatening. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


UNDERGROUND STORAGE - THE UNDERSTUDY

Industrial plants do not generally win awards for aesthetics, and tank terminals are no exception. It is hard to see a future where refineries are hidden underground, but at the same time, the use of rock and salt caverns to store various types of fuels is well known. Use of the underground per se is nothing new, for living in, for tunnelling to get from A to B in secret, for taking refuge, for secret government bunkers or laboratories, to house museums or private collections, for storage of food, archives, …and yes, of fuel. There are numerous caverns, of rock or salt, in various locations around the world that have been, or are being, used to house crude oil and liquid gases safely and securely, with the added social and environmental benefits that going underground brings. Crude caverns in particular are becoming more attractive with the attention paid to the need for strategic stocks, good examples being found along the Texas and Louisiana Gulf coast for the US government’s Strategic Petroleum Reserve (SPR). Canada opened its first underground crude storage cavern in 2003. Caverns storing crude are also to be found in locations including Japan, Korea, Norway, Sweden, France, Zimbabwe and South Africa, and cavern storage projects for strategic reserves are also believed to be underway in India. Underground storage tanks (USTs) are still largely in the realm of retail outlets, where they are of course the norm, but a number of studies have examined the feasibility of installing bulk size tanks underground in various ways. Some have had success where particular conditions mean going subsurface makes sense but practical applications of bulk USTs are few and far between. Cavernous capacity Construction of an underground cavern generally comprises of an initial geological investigation; extensive cavern stability analysis; initial rock support design; excavation works; and redesign of rock support as necessary. According to the International Tunnelling Association (ITA), salt formations offer a low cost environmentally secure way to store crude oil for long periods, and it compares the circa $3.50 (€2.6) per barrel cost of storing crude in artificially-created underground salt caverns with the $15-18/barrel cost of using conventional ASTs. Artificially-created salt caverns are made by drilling a well into a salt formation and injecting huge volumes of fresh water, which dissolves the salt, creating a void. The exact dimensions of the cavern can be controlled by controlling the pressure and direction of the water injection. A major benefit of storing crude in a cavern is the natural temperature difference between the top and bottom of the cavern, which keeps crude inside constantly moving and maintains a consistent quality. Geological pressures seal any cracks that might develop in the salt formation so that crude oil cannot leak from the cavern and, providing the site is below the level of the ground water table, oil can be stored directly against the rock surface without any steel or concrete lining. Stored product is extracted from salt caverns by pumping brine into the cavern. Because of density differences, the brine does not mix with the stored product and forces the product out of the cavity. When brine is removed from the cavern, it is stored in specially-constructed brine storage ponds and can be used over and over again, minimising environmental impact. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


MIXING IT UP

In many areas of fuel processing, blending and mixing are two of the most significant, yet basic operations. For the simplest fuel blending, two or more components are combined and diffused by means of flow movements. This results in a uniform compound, the elements of which are in the smallest possible volume. The process of bringing two or more liquids together covers a range of technologies, including static in-line blenders, dynamic mixers, multi-stream blenders, top entry mixers, positive displacement meters and injection systems using multi-headed reciprocating positive displacement pumps. All have their particular role to play both upstream and downstream of tanks and within the tanks themselves where it is often necessary to keep blended products in a stable condition. In many industries, continuous in-line blending is highly desirable as it is far more economic than batch blending and allows other processes downstream to be optimised. Where a range of products such as automotive fuels, toiletries and beverages are made up from a common base, in-line blending and injection systems enable fast switch-over from one product to another to meet demand. In the case of the automotive fuels industry, multi-stream blending can be performed at the loading rack, thereby reducing dependence on multiple storage tanks. Blending technology gives companies greater flexibility, enabling customer-specific products to be produced on demand far more economically, even when taking into account the costs of investing in such systems. Additive injection is of great importance within the fuels industry, where dyes and markers, anti-foaming agents, cold-flow enhancers and lubricity enhancers are essential ingredients. The same can be said for the offshore oil exploration and recovery sector, where chemical injection packages for adding biocides, oxygen scavengers and anti-foaming agents are a continuous requirement. However, the types of technologies used are very different. Jon Denis of Netherlandsbased Enraf Fluid Technology says that in the fuels industry the whole concept is now about how companies differentiate their products or make them easier to handle and this involves adding various ingredients. ‘At one time, because of the small volumes of additive required it was easier to dose the additive in bulk storage,’ comments Jon Denis. ‘As additives became widespread, the need for flexibility drove additive dosing to the headers and load racks, which resulted in very small volumes of additive being required. Volumes of this proportion were difficult to mix and meter and it is this that has led to the development of new dosing techniques.’ To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


TANK CLEANING IS A DIRTY BUSINESS

It might take a year, maybe three or even five years, but at some stage in their operating life storage tanks will need to be cleaned. Vertical storage tanks, particularly those holding crude oil, heavy fuel oil, slops oil or catalytic cracker residue, will accumulate a collection of stones, grit, sludge and mechanical items swept down the pipeline or from the tanker making a sea delivery. Tank cleaning is neither an easy, nor an inexpensive operation, but it is necessary. The contents of the tank have to be reduced to a minimum level, new entries might have to be formed, a secondary storage facility made available to receive the residual product, services and utilities provided close to the tank, and if physical entry is required it must be gas free. Oil Pollution Environmental Control (OPEC), one of the best ways to extend the time period between cleaning is to install a submerged rotary jet (SRJ) mixer system as a permanent fixture. A similar unit can also be used as a temporary device fitted to the storage tank to enable it to be cleaned at any time. As a permanent feature of the tank’s maintenance system, the SRJ mixer is mounted in the centre of the tank, and used on an intermittent basis to control the formation of sludge – how frequently will depend upon the condition and characteristics of the oil, and the frequency of loading and discharge. The unit can direct a single jet, or two opposing jets of oil horizontally across the tank while it slowly rotates at a programmed rate. This action cuts into the sludge that has settled on the tank floor, re-suspending and homogenising the hydrocarbons that have become trapped in the sludge. About nine years ago OPEC was involved with a project for the Formosa Petrochemical Chemical (FPC) company. At stake was the potential to supply 28 centre mounted SRJ mixer systems for installation in vertical floatingroof storage tanks of 87 metres diameter, and a capacity of up to 700,000 barrels of crude oil. FPC undertook a detailed study of available equipment, including the use of side entry propeller mixers (SEPM), and compared the benefits and disadvantages of employing each of the systems commercially available. Ilsley says: ‘The most notable reason that FPC gave for choosing to go with the SRJ mixer technology was its ability to eliminate the buildup of sludge in the tanks, thereby maximising the amount of storage capacity available at all times.’ To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details


LEAK DETECTION AND PREVENTION

There are many methods used to detect leaks on tanks or pipes but only some are able to prevent environmental contamination. The best way to prevent and detect leaks is by using double walled tanks and pipes, and constantly monitoring the integrity of the interstitial space. In 1956 German law claimed that groundwater had to be protected against environmental pollution. Leak detection systems for singlewalled tanks have been developed and used up to the 1980s. Finding out that these systems still have some weak points an upgrade in the law in the 1970s required doublewalled tanks and more advanced leak detection systems. Within a short time there was a new standard, requiring and defining overpressure, underpressure and liquid leak detection systems. These standards have been taken over by other countries like Switzerland and Austria. Within the last 15 years requirements for double walled tanks and pipes equipped with under- or overpressure or liquid leak detection system spread throughout Europe and the world. Liquid leak detection systems work by filling the interstitial space with leak detection liquid and locating a header tank with a sensor on top of the tank. In case of a leak, leak detection liquid will enter the inner tank or the environment, causing a liquid level drop in the header tank which is recognised by the sensor. It is necessary to place the header tank higher than the ground water table, which might cause additional installation costs. Part of the functioning of the liquid system is that the stored product and/or the environment will be contaminated with the leak detection liquid in case of a leak. In many European countries the liquid systems are not allowed to be installed anymore as the used liquid itself is defined to be a water endangering product such as ethylenglykol with fungicide additives. Underpressure leak detection systems (also called the vacuum systems) realise the following monitoring principle: The pump in the leak detector creates an operational underpressure in the interstitial space. The operational and the alarm underpressure are adjusted so they are at a higher pressure than that of the stored product. The underpressure is high enough to suck product or groundwater into the interstitial space and up into the liquid stop valve, which is installed on top of the tank in the suction line of the leak detector. To read this article in full you will need to subscribe to Tank Storage Magazine or buy the back-issue. Click here for further details