Maintenance Technology

Drive On-Time LPG Deliveries

Reliable sliding-vane pumps and non-mechanical flow meters are keeping liquid-propane gas suppliers on schedule and their customers happy.

Fleet operators in any industry have one driving principle: to keep their vehicles on the road lest delivery schedules—and customer satisfaction—be compromised. With package handlers and suppliers of inventory to grocery or clothing stores, for example, that requirement can be pretty straightforward, i.e., just make it to the customer’s site and unload the cargo. For other types of suppliers, however, the task is often easier said than done.

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Thanks to the efforts of innovative product-transfer solution providers such as UK-based Meller Flow Trans Ltd., LPG-delivery company Flogas now has a next-generation, fit-and-forget solution for keeping its LPG-delivery vehicles on the road in the form of a product-transfer and metering system that incorporates Blackmer LGL series sliding-vane pumps and Flowcom 2000 flow meters.

Take liquid propane gas (LPG). Providing this product to customers is not just a simple case of arriving at the desired address and leaving a box on the front porch. While a truck is a critical and indispensable component in the LPG supply chain, actual delivery can only be accomplished if the vehicle is outfitted with a series of working pumps, meters, hoses, controllers, and monitors that enable transfer of the LPG into a storage vessel. Unfortunately, since the abuse of daily over-the-road travel can hamper the performance of sensitive transfer equipment, the need for reliable components is a critical concern for LPG delivery companies.

“Vehicles are notoriously damaging and require robust operation,” explained Mark Allcock, managing director for Meller Flow Trans Ltd., located in Bradford, United Kingdom. “We don’t want sensitive equipment on the vehicle that will not stand the test of time and the rigors of daily road use.”

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Since 1984, Flogas has operated a fleet of LPG tankers that make deliveries to bulk customers while also offering cylinder-filling services at its network of LPG depot terminals.

A systematic solution

Founded in 1960, Meller Flow Trans began as an industrial-engineering firm. In the years since, it has evolved to focus on and specialize in creation of product-transfer solutions for the United Kingdom’s transport industry, including development of cutting-edge LPG-delivery systems. Traditionally, these systems featured a mechanical metering component that governed LPG transfer from the storage tank to the delivery vehicle, and from the delivery vehicle to the customer’s storage vessel.

While mechanical positive-displacement oscillating piston-type meters have, over time, performed well in such applications, the fact that they require moving parts to operate makes them susceptible to damage that can put them out of commission and hamper on-time deliveries.

According to Allcock, although mechanical meters are reliable in their own way, things can go wrong with moving parts. “What we’re trying to do as a systems provider,” he said, “is bring together the most reliable pieces of equipment that we can find to give our end users, our customer base, a fit-and-forget metering and delivery system.”

In the search for a solution, eight years ago Allcock and Meller Flow Trans came upon the Flowcom 2000 flow meter, produced by Flow Instruments & Engineering GmbH, a European company based in Solingen, Germany. What sets the Flowcom 2000 apart from traditional meters is that it facilitates fluid transfer through venturi-based pressure-differential metering principles, rather than mechanical moving parts.

“These were the first people I knew of to use pressure-differential metering on trucks,” said Allcock. “The Flowcom 2000 is highly machined, a very, very accurate piece of equipment. It lends itself perfectly to the road-transport industry because there are no moving parts.”

The Flowcom 2000 turned out to be the final piece in Meller Flow Trans’ delivery-system puzzle that, over four decades, had included LGL series sliding-vane pumps from Blackmer, Grand Rapids, MI. (Blackmer is a product brand of the Dover Company’s Pump Solutions Group [PSG] based in Oakbrook Terrace, IL.) Working with the vast majority of LPG-truck fabricators in the UK, Meller Flow Trans has outfitted hundreds of vehicles with the Blackmer/Flowcom 2000 delivery system.

“We’ve been selling Blackmer cargo pumps in the UK for more than 40 years,” recalled Allcock. “It really is a fit-and-forget piece of equipment, very reliable, very easy to maintain when required, which is minimal to say the least.” As a result, he estimates that these pumps are used in 90% to 95% of the UK’s mini-bulk or bobtail LPG delivery trucks, and for good reason.

Operation of the Blackmer/Flowcom 2000 delivery system begins when the driver initiates it from a control box at the back of the vehicle. At that time, the prop-shaft-driven pump moves the LPG through a delivery line to a gas-bubble sensor that checks for pockets of air in the LPG. From there, it moves through a temperature probe that, if necessary, converts the temperature of the LPG to 59°F (15°C). Then it’s on to the flow meter, which creates a restriction in the line that builds pressure—high before the venturi and low after the venturi. A differential pressure transmitter converts the pressure into a 4-to-20-mA signal that’s sent back to the control box where the driver can read the measured flow in volume or mass.

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After searching for a dependable LPG-transfer solution for more than eight years, Mark Allcock, right, managing director for Meller Flow Trans, was able to supply the Flogas team, including mini-bulk delivery-truck driver Paul Ward, left, and depot manager Gary Rolfe, center, with a reliable metering system featuring the Flowcom 2000 flow meter and Blackmer sliding-vane cargo pump.

Guaranteeing satisfaction

Another of Meller Flow Trans’ long-standing relationships in the UK LPG industry is with Flogas, Leicester, United Kingdom, which has been a customer for more than 30 years. Flogas entered the UK’s LPG market in 1984 with the acquisition of Portagas, and has grown to the point that it now has LPG-delivery operations in Ireland, Northern Ireland, Sweden, Norway, Belgium, and The Netherlands. In the UK, Flogas operates a fleet of LPG tankers that makes deliveries to bulk customers, while also offering cylinder-filling services at its network of depot terminals.

“At the Flogas site in Leicester, we have a wide variety of customers, cylinders, bulk, we do commercial bulk customers, a lot of dealers that do a lot of business for us,” noted Gary Rolfe, depot manager at Flogas’ Leicester LPG terminal. “We have more than 100 mini-bulk trucks in the company, and have been putting on a stronger, better metering system on the trucks. The Flowcom 2000 meters are certainly reliable, faster, and a lot easier for our drivers to use.” Moreover, as he characterized it, the whole process is simpler for all parties involved.

As a mini-bulk delivery driver for Flogas, Paul Ward is on the LPG industry’s front lines every day. His opinion of the Blackmer/Flowcom 2000 solution’s inherent reliability is clear. “It’s good to know,” he emphasized, “when I set off on my deliveries in the morning, that the pump isn’t going to cause me any problems, and that I can make my deliveries efficiently and safely.”

Application Specifics

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Equipped with a Blackmer LGLD2E pump (2-in./51 mm), Flogas’ mini-bulk trucks perform hose-reel deliveries through 130 ft. (40 meters) of hose at a flow rate of 53 gpm (200 l/min). On its larger bulk-delivery semi-trailers, the company uses LGLD4B pumps (4 in./102 mm) that are capable of achieving flow rates as high as 185 gpm (700 l/min).

Featuring a cavitation-suppression liner that reduces the type of noise, vibration, and wear caused by entrained vapors, these pumps are well suited—and UL-listed—for LPG service. Their sliding-vane design also gives them significant self-priming and dry-run capabilities.

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