Cornell Pumps often receives queries from the pump industry about its hot cooking oil pumps.
For some reason these pumps always hold a special attraction to people who have a technical mind-set. Or maybe it's just because of the end product – fried snack foods…
Cornell has been producing a series of pumps for this application since the 80s. Therefore, now is an opportune time for a technical feature of the most important characteristics of a hot cooking oil pump.
The problem
When fresh products are immersed in hot cooking oil during the frying process, water vapours are released from the product into the oil changing its consistency and temperature. This temperature and liquid property transition requires the oil to be circulated through the fryer and a heat exchanger.
Obviously, at a temperature of 180° Celsius or more, the cooking oil can't be pumped using a standard centrifugal pump. In addition to sealing issues there are several other technical challenges which need to be resolved in order to guarantee a reliable pump system. During the pumping process water in liquid form travels along the bottom of the fryer until it reaches the pump suction, the action of the impeller breaks up the water into smaller droplets that flash into steam. This presence of steam doesn’t just cause damage to the pumps through the possibility of cavitation, the resulting turbulence and vibrations are also detrimental to the pumps performance.
The solution
Firstly, selecting the right pump is of vital importance. A cooking oil pump obviously has to cover the system curve, providing the lowest possible NPSHr. This is why in practice cooking oil pumps generally work a little to the left of the BEP – Best Efficiency Point.
In addition, Cornell Pumps has developed several technical innovations which reduce the chance of cavitation or other pump damage to practically zero:
Anti-cavitation system, here a small amount of oil circulates back to the heart of the impeller through the vapour suppression line. The high pressure jet into the impeller eye suppresses the vapour bubbles until they have passed through the pump.
External balance system, this ensures that any build-up of debris around the shaft sealing is transported to the suction side of the pump to prevent damage to the mechanical seal. In addition, Cornell’s external balance line equalizes pressure between the impeller hub area and the pump suction to reduce axial loading action on the impeller, shaft and bearings.
609S ʺOʺ Seat Mechanical Seal, as standard, Cornell uses a shaft sealing which is suitable for cooking oil temperatures of up to 200° Celsius without the need to install external cooling systems.
For extremely high temperatures there is the option to add a water-cooled mechanical seal that can withstand oil temperatures of up to 288° Celsius.
The result
The only thing that counts is the result; users in the snack and food industry often work in shift rotations, and they don't want to worry about the technical side of installations and pumping systems.
There are now countless Cornell hot cooking oil pumps running all over the world, whose users know that pump yield and up time are both at the maximum level. Down time simply isn't an option!
The picture shows three pumps of the 8H-F18K type, these are the largest hot cooking oil pumps that Cornell has in its range. These units will be used in a new project in which the operating capacity will be 770 m3/h @ 40 mwc. With an efficiency of up to 88%, the motors power is limited to 90 kW.