Feed-transfer peristaltic Pumps

We all know that in a biological fermentation process, environmental factors influence the rate of an organism’s growth. In an ideal bioreactor, most of the living cells like bacteria, fungi, algae, yeast, and molds proliferate in four different phases. Lag phase, log phase, stationary phase, and death phase.

In the lag phase, organisms try to adapt themselves to the environment and culture conditions in a reactor and then they start to multiply. When their multiplication capacity becomes proportional to the present cell density in the reactor, they grow exponentially. This phase is known as the log phase. A point of time comes in the stationary phase when the cells use up all the nutrients and substrate while multiplication and due to lack of nutrients environment of the reactor change. A drop in pH due to increasing acidic constituents produced by multiplied cells is observed and, the formation of inhibitory products like organic acid is below or above the tolerance band for species. Due to unfavorable culture conditions, eventually, cells die in the death phase. It is recommended to add all essential nutrients and substrate at a few intervals, after the log phase and before the stationary phase of cell growth. Vigorous and continuous agitation in a reactor leads to foam formation which is again not good for cell growth.

To achieve a suitable growth environment it is necessary to go for dosing feed (to provide sufficient nutrients), acid/base (to balance pH in the vessel), defoaming agents (to eliminate bubble formation) with the help of peristaltic pumps. These pumps are special products that can transfer feed, acid/base solutions, and other nutrients without contamination in a running batch of fermentation process with more accuracy and quantitatively. Thus, known as batch transfer peristaltic pumps.

Product Amerging- Amerging peristaltic pump is easy and convenient to operate. It is designed to be supportive and compatible with the whole reactor system. The pump space is compact and equivalent to reactor controllers. Less viscous to more viscous liquids can be pumped at lower and higher-pressure rates.

• Amerging peristaltic pump is a piece of smart delivery equipment that has been widely used in various industries like Biotechnology, Biopharma, Chemical, and Agriculture industries.

• It is a solution to neat and precise feeding requirements for a particular process application. Reduces labor costs, provide hygienic transfers, clean and pollution-free, without contamination risks to give better results.

• Delivers with accuracy, helps in the determination of liquid stability, reliability, and reproducibility.

• It is based on the constant flow of liquid, can easily calibrate the flow by changing the speed of the pump.

• It can be used for a long run process for a long time, can maximum speed up to 600 rpm without damaging the pump body. It does not require any fill-ups as the pump is a self-prime pump. Work without the need of filling and emptying.

• A pump that can deliver sensitive and corrosive organic solutions which are no damage to itself. It is easy to replace pump tubes after using strong acid and base liquids. It can also transport high-temperature liquids up to 100 degrees continuously without damaging pump components.

• It can work in reversible directions.

• Simple maintenance- only need to replace tubing consumables, when transporting solutions of different properties.

How to choose a suitable pump- Well, the solution to this question is to focus on two issues.

• Application- What is the main application of the pump? Which solvent is going to pass through this pump? Once you know your industry and application of peristaltic pumps, then it will be easy to distinguish which one will be suitable for work.

• Medium- Based on the type of medium, its temperature, constituents, viscosity, and flow rate you can choose a peristaltic pump.

In general, small flow rates are usually used in laboratories as they require high accuracy whereas in the case of production and packaging high flow rate pumps are used. Similarly, the price for high precision and accuracy will be more compared to other pumps. So, pumps used in industries and laboratories/ medical treatment are different according to their flow rates and how viscous is the solution.

Working principle of peristaltic pump- The pump tube of the peristaltic pump is compressed and displaced by the pressure roller during the working process. With the displacement of the pressure roller, the pump tube that is not compressed by the runner will rebound naturally. This process is a peristaltic process. This peristaltic process pushes out the substance in the pump tube and therefore produces a pumping effect.

A negative pressure is formed at the inlet end of the pump tube, and the liquid in the pump tube flows along with it, and the liquid will flow out of the outlet end of the pump tube.

Tubing materials- The main objective of the tube materials used in pumps is to transport liquids in a contamination-free system since only part of the pump is touched by the solution in the interior of the tubing. Generally, materials like silicone, VITON, PP, PVC are used based on the type of solution to be pumped.

PVC is used when the acid or base solutions are fed in the reactor yet are cost-effective and the most common type of material which can withstand aqueous solvents as well. But certainly, they cannot be autoclaved and have almost no tolerance for corrosive solvents. silicone tubes on the other hand are used for solutions having a percentage of alcohol, compatible with corrosive fluids, and have a longer shelf-life. It can tolerate higher temperatures and can be autoclaved.

Factors affecting pumps- At the pump inlet a roller shoe squeezes the hose trapping liquid in the tube ahead of it. As the roller shoe rotates liquid is pushed out the pump's discharge. When the roller shoe releases the hose after discharge a momentary void or pocket is created where there is no product. This creates a partial vacuum as some product is actually sucked back to the discharge. This action along with normal pulsing action created by its positive displacement nature makes the peristaltic pump very difficult to dampen the discharge flow. Results in the flow pulsing as it comes out as discharge and that there is a very large swing in pressure on the pressure gauge. the flow actually stops at every rotation of a roller shoe.

Another problem that we hear is the tube vulnerability- prone to aging, losing elasticity, and damage under continuous working conditions. Well, let us discuss how we can overcome these situations!

Troubleshooting pumps-

• Normally, the life of ordinary silicone pump tubes is about 200 hours when the runner is continuously running at 100 RPM, if the pump tube requires a long-term operation of the peristaltic pump or is rarely replaced the pump tube, it is necessary to reduce the speed of the peristaltic pump as much as possible or choose a peristaltic pump tube with longer life.

• Also, make sure the nature of the liquid is compatible with the material of tubes in the industrial environment.

• To reduce pulsation problems and protect piping and system components, it is recommended to activate the dampner or use an inlet stabilizer by opening an isolation valve. Using dampner the flow becomes steady and smooth and no fluctuations of pressure are observed.

Summary- Peristaltic pumps are precision pumps covering laboratories and industrial markets. The rollers of the pump head squeeze and release the tubing cyclically, the tubing generates suction under its own elastic force to pump fluid. It can help in the filtration process, purification, drug solution transfer, the transmission of acids, bases, organic solvents, and other industrial applications. We can choose the type only by knowing our industry, the medium we carry, and the fluid properties of the medium. From a safety point of view, another pump called a gear pump can be used for higher flow rates, and for that different products are available.