A change in bottle design from a simple, symmetrical shape to an asymmetrical but ergonomic shapes caused problems for a domestic product manufacturer.
During the bottle filling process in many manufacturing units, empty plastic bottles are carried in single file on narrow conveyors, similar to those on airport baggage carousels and for many years those bottles have been stabilised on the line by vacuum fans beneath the belt creating a negative pressure, ultimately sucking the bottle securely to the conveyor to prevent it falling or moving out of place.
The change to a new bottle shape led to instability at one point on the line. The production engineer responsible for the production line, correctly identified that they could increase the vacuum by raising the current fan speed and by increasing the supply frequency to the motor from 50Hz to 66Hz, could obtain the required stability. However the increased speed and heavy duty on the fans meant that the fan motors were burning out regularly every two weeks. What the engineer had not taken into account was that the increase in fan speed had more than doubled the loading on the motor, hence the regular motor failures.
John Holden, our technical manager, extrapolated the curve of the medium pressure CMP fan (a forward curved single inlet centrifugal fan from Sodeca) at the new frequency and by taking measurements at the fan discharge was able to calculate the air volume being delivered and hence the pressure developed by the fan.
Using this duty point John selected a suitable fan from the Axair range of CAS high pressure blowers, further increasing the vacuum and bottle stability and preventing the problem of motor failures.
The bottles would then be securely held along the moving conveyor to be filled and capped before making their way into stores and homes Worldwide.