Description of standard freezing cabinet MEC
MEC developed a standard cryogenic cabinet series with 2 different dimensions:
- “MGM” Model, engineered to contain 1 trolley with dimensions 600×800 mm
- “MPM” Model, engineered to contain 2 trolleys with dimensions 600×800 mm
Stainless steel 304L, Satin finish, Thickness 1.5mm
Stainless steel 304L, Finish 2B, Thickness 1.5mm
Structure made by stainless steel 304L
A collapsible ramp is fixed to the doorjamb. The inclination allows an easy entrance for the trolleys into the freezer.
Internally and externally fully weld at TIG, in conformity with the regulation HACCP.
The freezer roof is supplied with 4 winglets, slightly bent, made by stainless steel with thickness 10 mm. They have a hole whose dimensions are suitable for the connection with belts that support the lifting with crane.
A tubular bumper has been installed in the posterior wall of the freezer, about 1.000 mm for the floor. This bumper has been engineered to stop the trolley and to avoid any crash against the bottom wall.
Freezing cabinet dimensions
The removable parts (ejection collar, bumper, eyebolts, etc.) are not included in the reported dimensions. Dimensions tolerance: ± 5mm or 2%.
|Weight||870 kg||1.270 kg|
Walls/Door: the thermal isolation has been realised with expanded polyurethane (without CFK), with an average density of about 50 kg/m3, and class E. Thickness 120 mm, conductivity factor λD = 0.021 W/mK. Floor: the floor has been built with 2 stainless steel plates with thickness 3 mm, between those a panel of P.U. has been inserted. The interior has been reinforced with isolating spacers.
The door is equipped for the opening with the following components:
- Stainless steel hinges
- Lacquered steel handle
- Closing locks in composite material + lacquered steel
A supplemental security handle (stainless steel) has been inserted in the cabinet, which allows the emergency exit. The handle, the locks and the hinges are developed to be used and cleaned in food environment with moderately aggressive agents (directive IAA).
The fan blades have been installed to suck up the air through the centre of the fan, and to blow the gas through the opening near the deflector. The injection points for the nitrogen or the CO2 have been installed next to the fan blades and they are oriented in the same direction as the airflow. Stainless steel plates protect the fan engines.
3 engines inside the cabinet model MGM (6 engines for the model MPM) from 0.75kW -1450 rpm. Shaft 19 mm Ø, shaft extension in stainless steel (36 mm Ø), standard flange B5
HasconWings with 5 blades (TM440/5-5°/MD/PAG/Rot D/LDD F3D), diameter 450 mm, material with steel core
The deflector is fixed at the cabinet wall, but it can be easily disassemble to execute maintenance or specific cleaning
The engines stops at the bottom pressure. The door is opening completely only after a pre-defined delay that allow the complete shutdown of the ventilation engines. The door can be open from inside in case of workers trapping. To facilitate this operation the door has a handle that allows the opening in an easy and instinctive way by pushing it toward the exterior.
Spurt system for different gases
INJECTION ON N2
INJECTION ON CO2
The gas injection has been achieved with a spurt ramp installed inside the freezer that runs down next to the ventilators with an upside-down U form (2 ramps with cryo-box MPM). The liquid/gas transformation occurs through calibrated holes on the descending parts of the spurt ramp, which are designed to distribute the gas on each plates of the trolley in a uniform way. The manifold of the spurt ramp is installed inside the box.
The gas injection and the carbonic snow spurt occurs through a multiple installation with a spurt connected to each ventilator. The spur system is for the main part outside the cabinet, it is made by stainless steel and it is properly isolated. A cryogenic valve is connected with each spurt in order to control the gas entrance.
Connection to the extraction
The exhausted gas extraction occurs with overpressure, through an opening on the freezer roof.
- Diameter D206 – D200 (external – internal) mm
- Diameter collar D206 mm x H100 mm, removable
If a extraction fan is installed on the freezer, to allow the forced gas extraction, its diameter should be at least 300 mm, in order to avoid obstructions o resistance to a natural extraction in case of fan malfunctioning. An extraction fan can create a depression inside the cabinet, which makes hard the door opening. During the opening, the gases inside flow out.
The electrical components are grouped in an electric cabinet. This is installed on the same side of the fan. A door allows the components accessibility. This door is locked with triangular key.
- Structure AISI 304
- Class IP55
- Feeding 3 x 400V + T + PE 50 Hz (± 5%)
- Door the door has a triangular key. It is sealed with rubber washer
- Transformer 220V/24VDC, 150VA
- Certificate CE IIA
Thermo-regulator for 1 set of freezing parameters that check the room temperature
Thermo-regulator for 1 set of freezing parameters that check the temperature of the product heart
Temporization of spurt pause for the cryogenic injection
Temporization of the cycle duration
Temporization to define the ventilation time after cycle end
PLC to manage pre-defined solutions
The typology, the model and the brand of the components has been chosen by MEC, unless specific requests ordered in advanced by the customer.
Probe of product temperature Pt100 that manages the process not with the room temperature, but with the temperature of the heart of the product.
The freezers must not work in environments without monitoring systems, which control the composition of the atmosphere in the environment. Those sensors are not included in the equipment and have to be purchased and installed by specialized companies according to the existing laws.
Certifications and documentations
The cabinet is supplied with handbook in Italian. The cabinet is designed and built according to the CE regulations. Furthermore, the following documents are included:
- CE declaration
- User handbook
- Instruction handbook
- List of recommended spare parts
- Maintenance notes
- Security symbols
- Security instructions for cryogenic equipment
The machine is built according to the following European regulations:
- Machines directive 2006/42 CE
- European directive 1935/2004 regarding food applications
- EN13371 cryogenic containers – Coupling for cryogenic usage
- EN13648-1 cryogenic containers – Security instruction to protect against overpressure