Documentation:VWR Drying Oven
What are the drying ovens for?
The drying ovens are typically used to dry soil to determine soil moisture. The suitability of non-soil materials must be confirmed by checking the equipment manual for each oven.
Description of equipment
The VWR 89511-412 is a forced air oven. Forced Air ovens are the optimal choice for fast drying processes, removing humidity faster than gravity convection units. In a forced air drying oven, the forced, blower-assisted airflow design offers excellent temperature uniformity and fast recovery. This unit has a temperature range of 50oC to 250oC with a temperature alarm and a dual sensor safety concept are providing peace of mind. For data monitoring the oven can be connected with a standard RS-232 interface to a computer. Heat stays inside the unit due to a unique insulation design, with benefit of low energy consumption and cool outside. Air exchange can be controlled by a damper - open it for drying to remove humidity quickly, and close it for heat treatment with highest requirements for temperature accuracy.
General Safety Guidelines
This SOP applies to anyone who intends to use the drying ovens. Any questions regarding their use are to be directed to the APBI Teaching and Research Support Technician (1st) or the Operations Manager (2nd). Anyone who intends to use the drying ovens is to review this SOP.
The following guidelines outline hazards associated with the use of the drying oven:
DO NOT LOAD OVEN with tissue, material, or liquids that:
· Are easily flammable, combustible or explosive
· Release poisonous vapor/dust that forms combustible mixtures when exposed to air
· Exhibit exothermic reactions, are pyrotechnical substances (eg: flash powder)
· Create a humid atmosphere
· release dust
· exhibit exothermic reactions
· are pyrotechnical substances
DO NOT exceed the specified hurdle load to ensure sufficient air circulation and uniform heating.
· VWR
o Maximum load: 25kg/55lbs
o Do not use more than 70% of the maximum surface area of the work space.
o The bottom floor of the chamber must be kept free and clear of objects and never used as a shelf.
o Bulky objects in the work space that dissipate heat may impair heat distribution
· ECONOTHERM
o At least one inch (2.5cm) should be left between objects placed on the shelves.
o The bottom floor of the chamber must be kept free and clear of objects and never used as a shelf.
o At no time should solid shelves be substituted for the shelves that are provided. Additional shelves and shelf supports are available from Thermo.
DO NOT place sealed containers in chamber. Sealed containers filled with materials do not provide room for expansion or evaporation, may develop vapor pressure as temperature increases.
DO NOT place plastic materials that melts at extreme temperatures as this poses a fire hazard. (If plastics are placed in the oven, do not leave it unattended)
DO NOT store containers filled with acidic or caustic solutions within the chambers, as vapors from these materials will attack the chamber interior and electrical components.
DO NOT use these ovens for food service or the preparation of meals.
Required PPE
· Always wear heat resistant gloves when loading / unloading into a hot oven.
· Lab coats and closed toed shoes are required in the laboratory.
· Use appropriate PPE for specified cleaning solutions where required
WARNING: All internal surfaces become hot. Wear appropriate gloves and
other PPE when removing items from the oven or loading into a hot oven.
Setup Procedure
Consult the manual for installation instructions. These are beyond the scope of this SOP. For long periods of no use, the oven may be unplugged from the power source. Before reconnecting the oven to the power supply, check the plug and power cord for damage. Do not use damaged cables for connecting the oven to the power source.
General Operating Instructions
The general operating instructions are as follows:
· Fill in pink oven use form with a dry erase marker to ensure other users know when the oven will be finished operation.
· Check that door seals properly. Notify Technician if seal is damaged.
· Turn ON:
o For Econotherm press the ON/OFF switch to the ON position.
o For VWR turn the oven on by pressing the On/Off button for 2 seconds.
· Set the temperature:
o For Econotherm rotate the Temperature Control knob to achieve the desired temperature (4 for 105 °C). Note: Temperature has stabilized when the lamp turns on and off at regular intervals.
o For VWR adjust the temperature set value. The temperature controller will start adjusting the workspace temperature to the set value.
· Load samples into the oven ensuring that:
o At least one (1) inch (2.5cm) of space is between objects placed on the shelves.
o The bottom floor of the chamber is kept free and clear - it is not a shelf.
· Shut down oven:
o For Econotherm, press the ON/OFF power switch to the OFF position.
o For VWR press On/Off button for 2 seconds.
· Clean up any spills that occurred.
· Leave temperature controls at 4 (105 °C), the standard temperature for drying soil.
Note: When the lamp above the Temperature Control is illuminated, an electric current is being applied to the heater. It is normal for this lamp to cycle on and off during operation of the oven.
· Unplug AC power plug to power down the oven completely.
Maintenance
Regular Inspections
The drying oven is to be inspected and a log recorded a minimum of once per year. Before connecting the oven to the power supply, check the plug and power cord for damage. Do not use damaged cables for connecting the oven to the power source!
£ Check power cord for damage
£ Check the oven for overall cleanliness and remove any debris from previous processes.
£ Make sure that the air inlet is not obstructed or blocked by any adjacent objects. If an air filter is present (optional on VWR), check to see if it needs to be replaced.
£ Check integrity and proper seating of the door seal.
£ Check vent shutter cap is in good condition (Econotherm)
£ Check door gasket to ensure it fits firmly against cabinet at all points. Replace torn/ damaged gasket.
£ Check required clearances against the operations manual.
£ Check internal temperature by placing a thermometer in the oven and turning the oven on until it reaches stable temperature. Ensure 1 hour minimum time is allocated for an empty chamber to stabilize at the set temperature setting to equilibrate between ambient and operating temperatures.
Cleaning Procedures
Be sure to clean all spills as soon as possible – do not leave spills for the next user. Remove all samples from work place and put them in a safe place. Wipe the interior of the oven with a dampen cloth. Do not use chlorine-containing disinfectants as they can corrode stainless steel and galvanized metal surfaces. If a disinfectant is required please refer to the operating manual. Disinfectants with alcoholic content of > 10% may form an easily combustible environment therefore it is critical to avoid open flames / exposure to excessive heat when using alcoholic disinfectants. The components must be wiped thoroughly dry after using a disinfectant.
□ Wear safety gloves and safety goggles.
□ Wear mouth and respiratory system protection gear to protect your mucous membranes.
□ DO NOT use strong acid and alkaline cleaners (eg: HCl, H2SO4)
□ DO NOT use steel wool, brass scouring pads/ metal cleaning tools
□ DO NOT place any objects on the floor of the oven to prevent premature corrosion if liquids become trapped and localized hot spots in the work load.
□ DO use soft cloth/sponge/plastic scouring pad with MILD detergent solution (pH4-9)
Heat Resistance Check
WARNING
1. The unit must be completely disconnected from its electrical power source before any readings are taken.
2. Disconnect oven from its power source before proceeding.
(Refer to the wiring diagram at the end of this manual and locate the electrical leads for the heater).
3. Ensure to disconnect at least one heater lead before taking the reading with ohm meter.
Heater Replacement
£ Check the resistance between each lead of the heater and a base metal point on the oven chassis.
£ Check all wires leading to the heater for signs on shorting for electrical contact to the chassis of the oven.
£ Replace heater if:
i. the heater is opened (infinite resistance)
ii. the heater reads less than 5 ohms (shorted heater)
iii. less than infinite resistance (at least a million ohms) between the heater and the chassis, the heater is shorted to the ground.
Troubleshooting
Check the manual for more information in case of problems or alerts. The manual can be found in the APBI Teaching Lab Quartzy database; request access from the responsible technician. Refer any additional questions to the responsible technician. When necessary, the technician will contact the supplier or other for servicing.