Thursday, March 29, 2012

Fully automatic prime/re-priming system handles air/liquid mixtures with ease

Cornell’s Redi-Prime® system addresses the fundamental requirement of customers to have pumps that are easy to operate, re-prime under lift condition, and eliminate carry-over issues of liquids when priming the pump.  Repriming becomes important when entrainment (due to a snore condition) or vortexing occurs. The vacuum pump is always running, so when the liquid component is missing, the float will drop to actuate  the priming process again automatically. This allows the unit to prime and reprime indefinitely.

The Redi-Prime® system utilizes patented technology, removing the requirement for a manual shut-off valve to ensure no liquid is carried over to diaphragm vacuum pump. The innovative sealing float box on Cornell Redi-Prime® systems utilizes a separator seat to accomplish this task.

Many other self-priming pumps employ a manual shut off valve on the air line between the vacuum box and the separator box. While this design addresses the problem of liquid carry over to the diaphragm vacuum pump, it does require the cost and inconvenience of an on-site attendant. Depending upon the issue, some carry over of liquid can deploy through the discharge pump onto the ground.

Redi-Prime® pumps employ a positive sealing float box; removing the need for an attendant to manually shut of the pump, and eliminating carry over discharge. These pumps use an industry leading wear elastomer formulation on the pumps. The design has been used successfully for more than a decade. Customer reported failure rate is considerably lower with Cornell products than in the industry as a whole. Other manufactures pumps have been reported to fail at significantly higher rates because of cracking and degradation of their elastomers.

Cornell’s Redi-Prime® perform so well in part because our pumps have an external lubricant and auxiliary gland—these innovations prevent drying of the seal faces when the pump is priming, re-priming, in stand by, or in run dry operating conditions. The external lubricant reservoir also acts as a heat sink, dissipating heat in the seal box area and extending seal life.

In some instances, customers have complained of excessive fail rates of competitors’ priming systems, leading to expensive downtime. When those priming systems have replaced with a Cornell system, the fail rate was markedly lower—saving valuable time and money.

Another key differentiating feature is the need for an enclosed bracket. Some pump manufacturers use one, which serves as an integral seal oil reservoir for run dry applications. Enclosed brackets increase the potential for bearing failure due to mechanical seal assembly breakdown. When this happens, pressurized liquid can flow through the failed mechanical seal into the integral seal oil reservoir / bearing frame assembly. Once that occurs, the bearings will be contaminated because of the lip seal fails in the bracket, ultimately causing the bearings to fail.

Cornell attacks the problem of seal failure with our patented Cycloseal® design. Incorporating deflector vanes in the backplate, a cyclonic action is created by impeller back vanes spinning in normal operation. That swirling action facilities the displacement of solids and abrasive material from the seal area, extending seal life and eliminating the requirement for a water flush.

The Cycloseal® also includes a John Crane convolution industrial duty elastomer bellows shaft seal constructed of tungsten carbide vs. silicon carbide seal faces and Viton elastomers. The John Crane seals are designed with a drive band and drive notches to stop overstressing of the bellows. Slippage is eliminated, protecting the shaft and sleeve from wear and scoring.

Additionally, the automatic adjustment feature associated with the John Crane seal compensates for abnormal shaft end play runout, primary ring wear and equipment tolerances. Axial and radial shaft movement is compensated for with uniform spring pressure.

Our commitment to your uptime is why Cornell is one of the few pump companies to offer the industry leading John Crane mechanical seals as standard.

To find out more about Redi-Prime® and Cycloseal technologies on Cornell Pumps, please contact your sales representative, or visit

©Cornell Pump Company 2012

1 comment:

  1. Liquid ring pumps can be single or multi-stage. Typically a multi-stage pump will have up to two compression stages on a common shaft. In vacuum service, the attainable pressure reduction is limited by the vapour pressure of the ring-liquid. As the vacuum generated approaches the vapour pressure of the ring-liquid, the increasing volume of vapor released from the ring-liquid diminishes the remaining vacuum capacity. The efficiency of the system declines as a result.