Gruenberg Open Container Dry Heat Vivarium Sterilizer

The Gruenberg Steri-Dry™ Vivarium Sterilizer provides the animal care market with equipment to sterilize animal habitat cages through the process of dry heat sterilization. These sterilizers are designed and built for lab animal science applications. This line of sterilizers has a maximum temperature of 340°F. Gruenberg sterilizers incorporate a flexibility of design that allows customization to suit virtually every application. These systems are built to ensure a smooth and quiet operation, which is an important feature when working around noise-sensitive animals.

Features

• Heavy-duty, fully welded structural steel frame
• Exteriors constructed of 16 and 18 304 L stainless steel with a #4 polish to withstand frequent wash downs
• Direct drive circulation system
• All interior surfaces are 100 percent continuously welded 316 L stainless for quick and easy wash downs
• Custom trucks, trays and other transfer carts are available
• Plate steel floor

Open Container Design

Chamber Construction

The Sterilizer is designed to accommodate 2 UOP carts that are 24”W X60”L x 70”H. The Sterilizer shall be constructed from a welded heavy-duty steel frame that supports the interior 304L stainless steel chamber and the exterior sheet metal. All interconnecting struts are non-continuous from inner to outer walls, thus keeping the exterior as cool as possible. A full 4” of insulation shall surround the work chamber on all sides, with the exception of the floor, which is a 3/16” thick plate.

Fully Welded 304L Liner

The oven’s liner shall be continuously welded thus creating an impervious barrier between the process chamber and the insulation material and preventing any contamination from entering the chamber from that source.

Inside Corner Radius

The chamber liner shall be formed with ¾”, inside-corner radii in order to simplify cleaning.

Doors

Double doors shall be fitted to the loading side of the oven. Both doors and oven are reinforced at all attachment points in order to maintain true door operation. The doors are hung on heavy-duty industrial hinges and close over a silicon rubber gasket and are held closed by a Brixon latches.

Air Heating System (Electric)

Seamless-tubular incolloy sheathed heaters that produce a high energy, efficient output, supply electric heat. The heaters are suspended in the plenum, adjacent to, but separate from the process chamber, so that work in progress and operators are protected. Terminal ends are inserted through the walls of the oven and use sufficient dead zones so that heat is not generated beyond the plenum. All heaters are wired with double nut connections.

Process Air Circulation (Oscillating Horizontal)

A high volume horizontal airflow system is installed in the unit to accomplish the distribution of airflow. A circulation fan located in a plenum chamber near the top of the unit, directs air into circulation ducts down both sidewalls. The air enters the workspace through a semi-pierced wall, flows horizontally across the product from one side then reverses its direction to flow horizontally from the opposite side. This oscillating airflow design provides for optimum impingement of the process air onto the product load. The spent air exits the workspace through a semi-pierced wall on the opposing sides of the work space, depending on what direction the air is flowing (right to left or left to right) of the chamber. The spent process air is then directed back to the conditioning plenum for re-heating and re-circulation.

Note: Output of the circulation fan will be controlled by a Variable Frequency Drive to allow correct tuning of the oven system.

Floor

The oven shall contain a 3/16” plate floor with front edge beveled edge for truck loading.

Filtration Air Pre-Filter

Air shall be pre-filtered through a 25-40%, 20” x 20” x 2”, roughing filter.

Air Intake HEPA Filter

A 18” x 18” x 6” HEPA filter, rated at 99.97% efficient at particles 0.3 microns or larger, shall be installed in a stainless steel housing on the incoming airflow side of the conditioning path. Challenge ports are provided for the verification of filter integrity. Access panels in the filter housing are secured with acorn nuts on 3” centers.

Air Exhaust HEPA Filter

A 18” x 18” x 6” HEPA filter, rated at 99.97% efficient at particles 0.3 microns or larger, shall be installed in a stainless steel housing on the outgoing airflow side of the conditioning path. Challenge ports are provided for the verification of filter integrity. Access panels in the filter housing are secured with acorn nuts on 3” centers.

Forced Exhaust System

A 290 CFM exhaust blower will be installed to the oven’s air exhaust system and be initiated by an output from the programmable temperature controller to provide a cooling capacity at the end of the temperature soak cycle. The blower will be 2-speed, with a lower rpm during the ramp and soak period, and a higher speed during the cooling period.

Temperature Uniformity

The oven is equipped to maintain a temperature uniformity of ± 5°F, at a test temperature of 280°F. Test temperature readings are taken within a volume of space not exceeding 80% of the work chamber or closer than 6” from any of the six interior surfaces and with the oven empty.

Controls and Instrumentation Control Panel

All operating controls for the oven are housed in a single panel, thermally insulated from the hot work chamber, mounted on the right side of the oven. Circuit wiring is complete, including a step-down transformer to provide the control circuits with 110 volt power. Wiring in the panel terminates in a suitable block for connection to the customer’s power supply.

Temperature Controller

A Yokogawa UT150 digital temperature controller shall be provided. The controller is microprocessor-based with single input, dual output, and auto tuning. Additional features include dual digital display, accuracy at 0.1% of span, easy setup, and operator friendly prompts.

Temperature Controller (optional)

A Yokogawa UP550-00 programmable time/temperature controller with digital set and digital, easy to read, 5-digit readout shall be supplied. The unit offers PID control with an accuracy of +/- 0.1% of reading. It operates on input from a thermocouple type sensor and provides a 4-20 mA output. Program capacities include 30 available program patterns for a total of 300 linkable segments.

High Limit Thermostat

A separate, independent Yokogawa UT150L high limit thermostat shall be provided to de-energize the heating system should the process temperature reach the customer’s preset limit. The high limit control must be manually reset to reactivate heating.

Airflow Switches

Pressure differential switches shall be installed and located in the air stream of the circulation and forced exhaust systems. Upon failure of either system, the airflow switch will de-energize the heater circuit.

Separate Main Power Relay

This relay is in addition to the normal relays serving the heater circuits. It is wired into the control circuit so that the high limit thermostat activates it. Should the main relays become mechanically frozen, as a result of extended use, this “back up” relay is deactivated and the heat system will be deenergized.

SCR/SSR

The power controls are installed to proportion power to the heaters only as necessary to maintain setpoint temperature. This minimizes swings in setpoint temperature, provides good temperature uniformity within the chamber, and conserves energy.

Door Switch

A door switch shall be installed on the oven to de-energize the heating and circulation systems when the oven door is opened. This is to prevent hot air from being expelled from the oven should the door be opened during the heating cycle.

Temperature Recorder

A Honeywell DR4300GP single pen recorder, with a 10” diameter circular chart and 24 hour chart speed shall be provided. The unit includes a thermocouple type temperature sensor. Customer is to specify desired chart speed at the time of order placement.

Process Timer (optional)

The oven shall be supplied with a microprocessor-based, solid-state timer that features a 4½ digit display with ½” tall digits. Programming is entered through a sealed, membrane keypad. Operational mode enunciators also appear on the display. The timer provides 5 user-selectable timing ranges up to 200 hours. Unless otherwise specified, the timer will be factory set for the 199-hour range. Timing accuracy is ±0.001%. U.L. and C.S.A. recognized.

Disconnect Switch

For safe electrical maintenance of the unit, a fused main power disconnect switch is installed on the access door of the control box. This necessitates the power to be disconnected before allowing the panel to be opened.

Magnehelic Gauges

Two magnehelic gauges are installed in the control cabinet face to register both process chamber pressure and pressure drop across the HEPA filters.

General Dryer Characteristics

Models sized to meet custom throughput requirements. (Volume, Width, Depth, Height)

Equipment Descriptions and Materials

* Subject to minor modifications if dictated by further engineering design study.