We’ve recently supplied a number of bitumen emulsion offloading pumps to various clients. Tanker offloading pumps like these are essential for offloading fluids at agricultural, chemical, food, fuel, and other facilities where bulk fluids are transported. These fluids can range from non-hazardous inert liquids to toxic chemicals, making the correct pump selection crucial after factoring in the fluid’s temperature, viscosity and toxicity.
Compressed air going out of favour
In the past, tankers have usually been offloaded by using compressed air to force the fluid out. However, there are a range of hazards associated with this method and there are now safer and more efficient ways to inject the supply container with compressed air. In addition, evolving regulations have shifted towards more controlled and safer pumped discharge processes.
Why is it dangerous to use compressed air?
Many manufacturing processes and the machinery used in industrial environments use some form of pressurised air or gas.
However, the fact that this is so commonplace, means that many people are unaware of the risks of blowing with compressed air. This is why it must always be handled with care as a small slip-up or momentary lack of attention can cause big problems.
Risks to people
There are many ways that compressed air can be harmful to operators:
- Even at relatively low pressures around 5 PSI, compressed air can cause serious injuries to the eyes, ears or other parts of the body
- Just 12 pounds of compressed air pressure can force an eye out of its socket
- Compressed air can enter the bloodstream through a break in the skin and cause air bubbles in the blood that can lead to a fatal blockage in a blood vessel
- If an air bubble gets to the heart, it causes symptoms just like a heart attack. If it reaches the brain, this may lead to a stroke
- The noise from an air hose can reach 120-130dB which is well above the Occupational Health and Safety Administration (OSHA) permissible exposure limit of 90dB. That kind of level can easily cause damage or even loss of hearing
Risks to the environment
Unloading tankers and removing the fluid by using compressed air to pressurise the container can lead to:
- Over-pressurisation of the container possibly causing an explosion
- The risk of hot liquids being discharged and damaging the local area and environment
Why a dedicated tanker offloading pump is better for the task
These types of pumps are specially designed to carry out low-pressure tanker offloading. They handle the task with greater precision and at higher safety levels, removing many of the hazards and challenges which can occur during tanker discharge:
- All of the contents of the container can be extracted
- Fluids with a low vapour pressure can be handled easily
- Flammable or toxic liquids where concentrations are unknown can be unloaded
- Viscous liquids or those which can solidify quickly can also be unloaded
- The risk of dry running is minimised particularly towards the end of the tanker discharge process
What if no power is available?
To help load or offload bitumen or emulsions between tanks, one option is to use an engine-driven vane pump as shown in the diagram below. If three or single-phase power is not available, this type of unit can be powered by an engine.
Vane pumps like this are reversible which makes them a good option for filling tanks or unloading as the pump can be operated in both directions. Vane pumps are usually fitted with a single mechanical seal, a double mechanical seal with barrier fluid, or gland packing.
In addition, they can handle a wide range of viscous fluids such as oils, diesel, petroleum, fuel oil and animal oils/blood. They can also pump non-lubricating fluids like solvents as there is no metal-to-metal contact within the unit.
What did we specify for our client?
Working with a dedicated pump manufacturer like North Ridge Pumps helps ensure that a low-pressure tanker offloading pump is designed to meet these challenges, and enable safe and efficient offloading across a wide variety of applications.
At North Ridge Pumps, we’re not restricted in the type of pumps we can specify. As the UK’s biggest pump supplier with over 25 years under our belt, we’re expert at selecting pumps for a wide range of uses and users.
We use our specialist knowledge and experience to deliver the right specification for every client, not a basic solution straight off the shelf. Just as important, we select the best pump for every project brief offering the most cost-effective option.
Our design solution
For this client, we specified an NRBAL3C three-inch horizontal long-coupled vane pump. This also came with the option of installing heat trace probes to lower the viscosity of the pumped liquid, and also prevent solidification of the bitumen within the pump head.
This low-pressure offloading pump delivers up to 30m³h at three bar and is fitted with a bypass valve to prevent over-pressurisation of any tanks or containers being fed – an important safety feature.
Using a vane pump design like this for bitumen emulsion transfer also ensures that the liquid is moved with low shear forces.
If you have an application requiring the swift unloading or loading of tankers, and need guidance on the best pump to use, speak to North Ridge Pumps to see how we can help.
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