Conversion of Silage Pit to Refrigerated Box Store

Store Brief

Required 600 tonnes of processing potatoes to be stored at 6°C with facility to CIPC gas throughout the year. Potatoes are stored for McCains through to June so a fridge and ambient system would be required. We have fitted a 42kw air mixing refrigeration unit.

Existing Building

The most suitable building was an old silage pit covered by a round roof Dutch barn. This building was 45000mm long x 8530mm wide x 6000mm high. We fitted a false gable end in at 36500mm give a store that held 600 tonnes with a new side roller shutter door for access.

Installation

We repaired the roof and fitted new steel sheets to cover old roof lights and filled in open area alongside of store. The gable end was sealed with a new curved gable end flashing.

The refrigeration unit is sited at the rear of the store with 2 x exhaust louvres to each side at high level.

We cut through the existing silage retaining wall that was brick and concrete – a job that would usually take 2 men x one day. The wall was reinforced like a bomb shelter. We ended up with a digger and pecker to create the hole, taking 3 days.

The louvres and cowls were fitted to the back wall ready for the refrigeration unit.

At low level around the store we clad the walls with timber framing and slab insulation and 12mm plywood to 1.2m high to stop the forklifts knocking the foam off when filling and emptying the store.

We constructed a false gable end with steel stanchions, timber purlins and clad with tin sheet to match existing gable end and fitted a steel personnel door.

A frame was prepared ready for the insulated roller shutter door, complete with top beam with brush strip seal.

Electrical

We now first fixed the electrical to louvres, fridge, air mixing fans, lights and roller shutter door.

The power came from the mains board in an adjacent store.

Sprayfoam Insulation

We then applied 75mm of sprayfoam on the whole store to give an insulation value of 0.030w/mk (Class 1 surface spread of flame). 

The store had to be blown down to clean and any loose concrete on walls was removed.

Final Fitting

Now sprayfoamed, we fitted the air mixing refrigeration unit into place and installed the air distribution tubes on top.

2 x Air Moving fans were fitted 2/3rds of the way down the store to help propel the air to the end of the store. The insulated roller shutter door was fitted and flashed around.

Refrigeration

The unit is a 42.0kw air mixing refrigeration unit that hunts for cheap rate electricity at all times, has automatic defrost on demand, a large evaporator coil to keep humidities high and a drying program to dry the potatoes when first into store. The controller is fitted with a USB memory stick so data can be looked at remotely on a computer.

CIPC

Within the box layout we have left 2 alleyways to distribute the CIPC positively.

Each gap is 900mm wide and covered on top with plywood and 710mm fan in the centre. 

The sides of the plenum are covered with plastic sheets to hold in the gas.

Opposite each plenum there is a gassing port and a speed control to slow fans down whilst pulling the gas into the boxes.

Electrical Works

We now second fix all equipment, test and instruct the customer on use of the store.