Whitley DG250 Workstation
Statements in red in the Detailed Specification refer to features and benefits which we believe are exclusive to Don Whitley Scientific.
1. Whitley DG250 Anaerobic Workstation
The Whitley range of anaerobic and variable atmosphere workstations combines advanced ergonomics, contemporary aesthetics and superb atmospheric conditions. The Whitley DG250 workstation is the entry-level model within the Whitley Workstation range.
2. Capacity
The workstation will accommodate up to 400 x 90mm plates.
3. Construction and Materials
The chamber is manufactured from 10mm acrylic for structural stiffness and optical clarity. Both during fabrication and after fabrication is complete, the structure is annealed. The annealing process relieves the stresses induced in the structure as a natural consequence of machining, bonding and polishing acrylic fabrications.
Don Whitley Scientific Limited guarantees the integrity of the chamber for ten years.
Other workstation components are manufactured from a variety of materials including stainless steel, mild steel, polypropylene and polyurethane. Each component has been designed and manufactured for optimum performance.
Physical dimensions: 810mm x 635mm x 760mm (L x H x D).
Incubation area: 650mm x 510mm x 240mm (L x H x D).
A removable shelf divides this space into two areas 250mm high. If the optional sliding trays are fitted then the lower area height is reduced to 210mm.
Working area: The working area is 650mm wide x 235mm deep with a height of 315mm at the front of the chamber, rising to 510mm immediately in front of the incubation area with a maximum capacity of 400 Petri dishes, the workstation offers the best capacity/footprint on the market.
5. Gas Requirements
The workstation will operate on either one cylinder of conventional anaerobic gas mixture (10% hydrogen, 10% carbon dioxide and 80% nitrogen) or one cylinder of
2011 Don Whitley Scientific Limited. All rights reserved.
anaerobic gas mixture and a cylinder of nitrogen. The workstation operates in either mode without any modification.
6. Gas Alarms & Control Systems
Various audible and visual system indicators, fail-safe devices and alarms are provided:
Low gas pressure: if the pressure of anaerobic gas mixture or nitrogen fed to the workstation falls below the necessary minimum level, a buzzer will sound and the relevant labelled lamp on the front panel of the workstation will illuminate.
Continuous flow: if anaerobic gas to the chamber flows for more than five minutes, a buzzer will sound and the appropriate lamp on the front panel will illuminate. The gas supply to the workstation will be cut off automatically.
Gas demand: a green lamp on the front panel confirms when gas is flowing into the chamber.
7. System Operation:
The Whitley DG250 workstation has been designed to operate with a slight positive internal pressure. Any pressure drop within the workstation is sensed and a pressure switch controls the flow of fresh gas into the unit. In addition, a timer controls the delivery of a small volume of gas at pre-determined intervals. This ensures that fresh gas is regularly introduced into the chamber, helping to maintain the finest possible anaerobic conditions.
We offer an option which will automatically gas the sleeves with the required amount of gas when the correct vacuum level has been drawn on the sleeves. This ensures that: 1) the efficient use of gas; 2) correct operation of the glove ports.
A cannister of palladium catalyst is fitted in a holder behind an access hatch at the left side of the chamber. The sachet is kept dry by the warm internal atmosphere passing over it. The function of the catalyst is to reduce levels of oxygen by causing any oxygen to combine with hydrogen contained within the anaerobic gas mixture. The water vapour produced by this reaction is removed automatically by a humidity control system.
A cannister of Anotox™ is fitted in a holder behind an access hatch at the right side of the chamber. Anotox™ is a Don Whitley Scientific patented compound, the function of which is to remove volatile fatty acids and hydrogen sulphide from the chamber atmosphere.
2011 Don Whitley Scientific Limited. All rights reserved.
The humidity control system ensures effective removal of any excess moisture in the chamber. The DG250 workstation is fitted with a fully automatic de-humidification system that does not require any operator intervention. The humidity level is controlled by the system microprocessor and a solid state humidistat located in the chamber. Dual cooling fans on the condenser panel ensure unrivalled efficiency and reliability of operation.
A pump, controlled by a timer, opens regularly for a set duration, allowing collected water to pass to an external reservoir and evaporate. The reservoir is fitted with a biocide-treated filter pad.
The operating temperature of the workstation can be set between 5°C above ambient and 45°C by adjusting the set point value on the temperature controller. Detailed instructions are contained within the User Manual supplied at the time of installation. A small internal incubator able to operate at up to 60°C (and with a capacity of up to 42 x 90mm Petri dishes) is available as an optional extra.
The DG250 anaerobic workstation can be fitted with monitoring probes for connection to an external monitoring system if required. One spare gland is provided as standard; other glands can be fitted during manufacture if requested.
7.7 Maintaining and Indicating Anaerobiosis
Maintenance of anaerobiosis in the DG250 anaerobic workstation is achieved through the reduction of oxygen by hydrogen in the presence of the palladium catalyst. The combination of hydrogen and oxygen occurs in the ratio of 2:1 by volume to form water vapour.
All that is necessary to maintain stringent anaerobic conditions is to ensure the catalyst is active and the ratio of hydrogen to oxygen is at least 2:1. Under such conditions oxygen concentrations within the chamber will be less than 5 ppm.
We advocate that at least one of the following control strains are used, namely Bacteroides fragilis, ATCC 25285; Bacteroides thetaiotaomicron, ATCC 29741; Clostridium perfringens, ATCC 13124. Growth of the control organism will clearly show the ability of the test system to support anaerobic growth. Additionally the size of inhibition zone around a metronidazole disk can be measured to provide a quantitative control measure. As metronidazole is only active under anaerobic conditions, the user will be alerted to possible cabinet failure should the inhibition zone size fall below pre-determined limits. Our Technical Note MA3 applies.
All Don Whitley Scientific anaerobic and variable atmosphere workstations are designed to provide generous working areas. Advanced ergonomic design ensures user comfort.
2011 Don Whitley Scientific Limited. All rights reserved.
The oval shape of the patented portholes allows greater freedom of movement and operator comfort compared with the use of conventional, circular portholes.
8. Plate Transfer System
Our patented porthole system provides both a means of sample transfer and operator entry and exit. Each porthole can be used to transfer up to 10 x 90mm plates (making it possible to transfer up to 20 plates in total) at the same time as an operator’s arms are inserted or withdrawn from the cabinet.
2011 Don Whitley Scientific Limited. All rights reserved.
Southern Cross seeks digital head and best use of the newspaper medium are amongthe other categories. Caxton Ctee chair Justin DrapeRadio company Southern Cross Austereo is seekingsaid: "The Caxton Awards is an opportunity to ac-a digital strategy and innovation head - a new roleknowledge and celebrate the best ideas being creat-introduced following business development and digi-ed