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Project CPCL - 1


We were contacted by a clay pigeon manufacturing company to quote for a pair of silo safety systems to be installed during a 7 day planned maintenance shutdown. A pair of silos are used to store limestone essential to the manufacture of thousands of clays per day, with production running 24/7. Both silos were being vented to a regular fabric envelope type filter via spiral ducting from the top of the silo which historically easily became overloaded and clogged during tanker filling meaning filling had to be done at a lower pressure than ideal with a resultant longer filling time. In addition there was an over pressure vent but no warning system for overfilling or over pressurising so the risk of the product escaping through an open pressure vent was always present. We provided 2 independent silo safety systems which each consisted of:

  • Silo mounted reverse jet cartridge filter with differential pressure pulse controller
  • Rotating paddle high level probe with ground test facility
  • Over pressure safety switch
  • Silo safety system control panel
  • Fill pipe butterfly valve
  • Tanker fill pipe coupling


Access to the location for installation was restricted by the production demands, a tanker delivery being required 5/6 days out of every 7 so installation of the safety system was not possible and required a planned maintenance shutdown period. The filter units are compact but in order to get them to the top of each silo a Hi-Ab crane with a 15m reach was required and the only suitable location for the crane was in the neighbouring specialist cheese factory car park, thankfully permission was kindly granted so access became a brie’s J. Local Electricians Ian Smith Electrical were contracted for the electrical install, an on-site meeting with their foreman and our install foreman ensure a plan was formed between FDL and the client which would see the work both commencing and completing within 5 days of a planned 7 day shutdown. Mounting panels were drawn and fabricated to suit and replace existing bolted panels on top of each of the silos but one of silos required a new 1200mm diameter hole cutting out to suit the filter. Where possible the smaller items were designed to be grouped together as space was limited, one of the existing over pressure vents requiring removal and relocation in order to successfully locate all items on that particular silo. All the equipment was delivered to site well in advance which enabled Chris, who would be in charge of the electrical install to familiarise himself with the requirements in advance. Once on site work took place largely as planned in advance.

Some highlights of the install

Project CPCL - 2


On site inductions and RAMS signing, work permits issued

Remove smaller existing ducting sections

Cut out the hole for the silo filter (fit temporary weather cover)

Electricians install containment ready for wiring

Mount control panels at ground level near tanker fill point

Project CPCL - 3



Crane on site, inducted and RAMS, liftplan sign off

Remove remaining existing ducting sections

Lift all large items and place on the top of the filters

Electricians wiring ready for connecting

Project CPCL - 4



Complete all welding tasks on silo’s

Install additional safety items on top of silos

Modify fill pipes to accept butterfly valve and coupling

Electrical connections made

Install and connect compressed air lines

Project CPCL - 5



Commissioning of safety system and control panel functions

Test of safety systems prior to tanker fill

Tanker lorry delivery split 50/50 into the silo’s

Maximum safe delivery pressure without triggering the immediate closure of fill pipe butterfly established

Filling rate/time observed

Project CPCL - 6



Full tanker load delivered into smaller silo

Alteration made to increase the safe capacity in smaller silo

before triggering the high level alarm

System acceptance


Project Manager: Stewart Callis Completed: May 2017