As the world converts over to electric vehicles, more and more vehicle manufacturers are shrinking their combustion engine range – it is still difficult to gauge when the combustion engine will be a relic of the past like the steam locomotive.
But hydrocarbon fuels remain big business, and at the core of the economy, keeping the wheels on the road or for that matter wings in the sky.
The refining, storage and transportation of these fuels require their own support industry and equipment to move and manage these commodities from source to consumption.
Purpose built vehicles and equipment are a niche that need to abide with many laws and regulations in order to keep it safe for us and the environment.
Key equipment like pumping and metering systems are often fundamental parts in the design of these vehicles.
Pumps and meters very often go hand in hand in the trucking business. That is of course if one is in the business of transporting liquids and in particular fuels. Liquid fuels include an additional component that needs close consideration and that is safety and security. With the ever increasing price of Petrol and Diesel and LPG (Liquified Petroleum Gas), taking care of these precious commodities can be quite a complex and expensive part of the transporters business.
Added to that the responsibility towards the environment and making sure spillages, emissions and contaminations are prevented.
From point of loading up until final delivery to the end customer pumps and meters can be used a number of times during the custody transfer stages.
From loading a tank truck at the fuel gantry utilizing high volume pumps (up to 2500L/min) and a meter to verify the quantity loaded. Followed by the fuel being pumped and metered from the loaded tanker into the next storage point e.g. Fuel depot or Fuel station and finally once again the product is pumped and metered into the vehicles it was destined to reach. Of course PETROLs and DIESELs are normally delivered to fuel stations via Gravity into underground storage tanks, but it is commonplace to store DIESEL fuels above ground for the industrial applications such as mining, farming and other commercial installations.
Without blabbering on too much about that and getting off topic – Consideration to using the right pump and meter system for the job can be the difference between being efficient…..or not.
When it comes to pumps – Typically those used on road tankers one will normally find a “vane” type pump is doing the job. These pumps are driven either via the trucks PTO system or by hydraulic motor if the pump is installed on the trailer side. They are super-efficient and much smaller and lighter in construction than alternate designs.
Metering can get a bit more complex and with many varieties and configurations available, one should investigate the options closely before making an informed decision. Typical meter types include vane meters, turbine meters and Venturi systems. Each of these are specific by their application designed to provide the most optimized solution in terms of accuracy and product safety.
For example – Vane meters are the most commonly used meter type for automotive fuels. However, one compromise is that they retain residual product at all times even when the tanker is empty. This requires then a second meter and piping system to separate different products i.e. PETROL and DIESEL in order to prevent contamination between them. The additional meter also has an added capital cost and eats into payload capacity as well.
An alternative solution is to use a Turbine meter system – The beauty of a turbine is that in the right design it will empty completely. This conveniently allows for only one meter and multiple products can be delivered without the risk of contaminating each other or creating cocktails inside storage tanks. The additional up side being cost and weight advantage.
Venturi meter systems are generally not commonplace in the automotive fuels market, but have proven quite effective in terms of efficiency and accuracy when applied in the LPG market. With no moving wear parts inside, these meters can maintain their accuracy almost lifelong and don’t suffer the same maintenance problems that a typical mechanical type meter has.
Another sector worth mentioning and analysing is the Aviation fuels market – Aviation fuels are typically split into two groups, each with their own range of blends. However, for the ease of the article we will just name them as AVGAS and JET (commonly called JETA1).
Like PETROL and DIESEL, the fundamental difference between AVGAS and JETA1 is the engine types they are used in. In the aviation world, refuelling of aircraft are divided into two groups – Overwing fuelling and Underwing Fuelling (Helicopters also fall into these groups depending on model and size)
Overwing fuelling applies to light aircraft types typically propellor driven and these use AVGAS fuel and the fuelling nozzle is a hand held unit similar to the type one will refuel one’s car at a service station with. The pumps fitted to these trucks are also typically “vane” type units but run at much slower speeds than Diesel pumps (around 60-150l/min).
Underwing fuelling applies to larger aircraft with JET Turbine driven engines, such as EXECUTIVE JETS, Boeing 737, and Airbus A380 etc. In this case the connection nozzle is positively secured underneath the wing of the aircraft with much higher flow rates applied.
The vehicles used to refuel these aircraft normally have very large storage tanks (too large to legally travel on public roads) and sophisticated platforms that must raise and lower to reach the underside of the wings. In fact, larger airports often do not use tankers but instead use a hydrant system underneath the apron. The vehicles used here are called hydrant dispensers and have no pumps or storage tanks. These types of vehicles fundamentally control the hydrant pressure into the aircraft and filter the fuel one last time.
In both cases of Overwing and Underwing, metering systems are used to measure the volume of fuel dispensed into the aircraft for billing purposes. Again, there could be a few options of meters to use, but normally a typical vane type meter works fine.
These trucks are never emptied completely and each type are typically dedicated to either AVGAS or JET. Filtration is key on these trucks with the emphasis on clean and water free fuel (for obvious reasons) – Safety systems are built into the fuelling process with devices known as “Deadman” control to ensure the operator is alert and focused on the task. In the event that the operator looses focus or even consciousness or does not respond on the “Deadman” unit, the fuelling process is stopped immediately, by closing valves and turning off the pump.
So – Refuelling as you can see is not a one type fits all operation. There are many factors which need to be taken into account. These vehicles are specialized and customized equipment, engineered often for bespoke requirements.
Alfons Haar is a German owned company, specializing in fuel handling equipment and fuel metering systems in the Automotive, Aviation and LPG markets. After 60 years in business, we have got pretty good at what we do.
For more information and support contact us on www.alfonshaarsa.co.za – Serving the South African Market since 1975.
