Eccentric values

Eccentric disc pumps with CIP technology can help manufacturers reduce maintenance and improve uptime and sanitary standards. Laurens Janssen, industrial sales & marketing manager at Blackmer explains how

Pharmaceutical manufacturing can be a challenging area for pump technology in that many applications call for process pumps that are capable of handling shear sensitive media and liquids that cause damage to mechanical seals. Also there is the requirement for pumps to have true clean-in-place (CIP) capabilities.

These requirements are addressed by eccentric disc technology, whereby the pump unit employs an oscillating eccentric piston to produce the pumping performance of a rotary positive displacement pump, creating a more consistent flow, even with changes in pressure and viscosity. Invented in France and introduced to the market more than 100 years ago, it has only been in recent years that the technology has reached the global stage. Today, this type of pump is best known as the Blackmer Mouvex C-Series (see figure 1).

The past decade has seen global competitive pressures and environmental protection regulations force companies to improve operating efficiencies, reduce product losses and improve sanitary standards. Eccentric disc technology pumps are specifically qualified to meet these requirements and, as a result, international demand for these pumps has risen steadily.

The oscillating motion of the pump disc on the cylinder causes very slow internal velocity, resulting in gentle low shear pumping action and lower energy consumption. Self-priming and capable of dry-running, this type of pump will clear both the intake and discharge lines of any residual liquid. Lubrication of all moving parts is provided by the pumped medium.

Looking at the factors that are fuelling growth in demand, the first benefit is its seal-less construction, which helps to eliminate high value product loss. Of even greater importance to users is the pump's true CIP capability. This is recognised as a significant economic advantage over pumps that require time-consuming disassembly between batches in order for them to be properly cleaned and sanitised. Blackmer's Mouvex C-Series pump can be completely drained, flushed and cleaned in place without there being the need for it to be disassembled. Nor is there any need to remove piping or pump housings, so maintenance time and costs can be reduced.

Eccentric disc CIP pumps are capable of handling up to 10,000 cps (46,000 SSU) liquids and working pressures of 5 bar - 9 bar, depending on the model. The speed range is 50-1000 rpm, with capacities of 0.6 l/m -718 l/m. Rated up to 150ºC, the C-Series has a particle size range of 1-3 mm and is effective at handling suspended solids with mild abrasives.

The C-Series is used worldwide for high value fine chemical applications and sanitary applications. The eccentric disc principle makes the pump extremely flexible and capable of pumping low viscosity, high viscosity and abrasive media within a single process without the output being affected by such variations.

An application where this type of pump has been installed as a replacement includes the feeding of glucose into a buffer tank for the manufacture of pharmaceutical syrup. The stainless steel bellows that totally enclose the mechanical transmission eliminates the traditional mechanical seal and safeguards against any possible leakage of this viscous fluid. Where used for drawing off lactacide gel with a viscosity of 1,500 cps and a temperature of 18ºC from a 1,000 litre container, this type of pump has been shown to give a far superior performance to that of a circumferential piston pump.

Even at low speeds the suction capability of the pump allows for perfect priming and draining of mobile tanks and stationery pipes. The seal-less design makes it particularly suitable for a broad range of media, including sticky and highly viscous liquid sugars, toxic chemicals and extremely thin products such as solvents.

The stainless steel C-Series holds 3A Approval Certification and is EHEDG (European Hygienic Equipment Design Group) approved, designed specifically to be flushed and cleaned in place. Other accepted technologies such as lobe pumps may experience a 15-20% loss of volumetric efficiency when designed for CIP drain ability with vertical porting. The C-Series does not experience any loss of performance due to porting and does not need to be by-passed to clean-in-place, provided the pressure does not exceed 3 bar (2 bar for Micro C pumps).

It is common for the CIP process (see figure 2) to begin with a water flush followed by concentrations of various cleaning solutions such as mild caustic and perhaps, reheating solutions that are circulated through the pump, piping and valves. The process concludes with a final rinse. In some cases, stream is used rather than water or other cleaning solutions.

Before starting the CIP cycle, it is essential to minimise the amount of residual product in the pump and piping, particularly if it is expensive or hazardous. The excellent suction lift and line stripping capabilities of the C-Series enable the reduction of residual product, thereby minimising product loss, easing cleaning and reducing cycle time. For optimum cleaning of sticky or viscous products, the flow through the pump is between 90lt/m and 900lt/m, depending on the pump model and less for thinner and easier to handle products.

In most CIP applications the centrifugal pump used for CIP cycles is positioned upstream of the C-Series, with the pumps being installed in series in order to take advantage of the C-Series pump's unique disc/cylinder design. During the clean-in-place process, the pressure at the pump inlet is higher than at the outlet, so the disc lifts from the pump cylinder allowing passage of water or cleaning solutions to flow through the pump for thorough cleaning (Figure 3). This feature eases the cleaning process and reduces cycle times so that the pump can be back in operation quickly. Unlike other technologies, the C-Series pump does not need to operate during the CIP cycle.

The most efficient CIP's generally comprise five stages, these being:

• Pre-wash with clean water at room temperature to evacuate remaining residues.
• Washing with an alkaline detergent, typically soda at 2.5% at a temperature of 80ºC to enable dissolving and evacuating any grease and proteins.
• Rinsing with clean water at room temperature to avoid mixing two different cleaning solutions.
• Washing with acid solution, typically nitric acid at 2.5% and room temperature to dissolve and evacuate any proteins and inorganic salts.
• Rinsing with clean water at room temperature to evacuate any traces of acid solution.

CIP technology can improve operating economics because it is fast, efficient and effective. Quite simply, where a sanitary process requires routine cleaning between process batches, CIP technology can improve uptime performance and reduce maintenance costs dramatically.