Customer requirements

Carroll & Meynell Ltd, a leading manufacturer of electrical transformers, moved to new premises to accommodate considerable growth in their business. Further growth caused them to re-think their production methods. The handling of the fine silica sand used to ‘pot’ transformers was a major bottleneck in their production line.

Silica sand was received in 25kg bags each of which had to be emptied into a hopper at ground level. The hopper was lifted on to a platform by a fork lift truck to provide a head of sand for filling around the winding within each transformer casing. Control of the sand was by hand-operated ball valves. These valves stuck open from time to time! All in all, it was a time consuming and very messy process - given that Carroll & Meynell are using around one and a quarter tonnes of sand a day!

Carroll & Meynell concluded that the optimum solution was to receive their dry sand in sealed 1 tonne big bags (FIBC’s), then mechanically convey it up to small holding hoppers above each of 2 production lines and to have a more reliable flow control valve at the end of the sand delivery tubes.

Spiroflow solutions

Spiroflow was identified as a potential supplier of screw conveyors via the internet. A meeting convinced Carroll & Meynell that we could take care of the whole system. Besides being a manufacturer of the flexible screw conveyors, with which our name is synonymous, we produce one of the most comprehensive ranges of bulk bag dischargers in the business.

A previous Spiroflow installation handling silica sand for potting electrical fuses served as an appropriate reference. This, together with, the obvious expertise of our engineers, convinced Carroll & Meynell to place an order for the complete silica sand handling system with us.

The Spiroflow system comprises a standard bulk bag discharger, a flexible spiral conveyor that lifts the sand 5.5 metres over a distance of nearly 5 metres, a diverter valve with tubular feed chutes to the holding hoppers, two holding hoppers with level probes (that actuate both the conveyor and the diverter valve at the conveyor outlet to ensure sand is delivered to the hopper in need of topping up), discharge chutes to the sand filling points on each of the two production lines and iris diaphragm valves to control the flow of sand. The cleanliness of the whole area around the Spiroflow system is a testament to the high degree of containment built in as standard.

The installation has been in operation for many months now and has literally transformed the output of the 110 volt transformers produced for the construction industry. Production is now up to 6,000 units a month – several times more than before.

Carroll & Meynell’s own engineers installed the system and, being electrical engineering specialists, they manufactured the controls system to our specification. As Director, Bob Carroll, concludes, “We started to get cold feet about doing the installation ourselves having manufactured the supports to drawings provided by Spiroflow - but it was so easy to install. It was spot on, it all slotted together well! It has been doing a sterling job ever since and has eliminated both the bottleneck and the housekeeping problems on our production line”.