ETHOS DESIGN FEATURES
Construction and Safety
The ETHOS is the most rugged closed vessel microwave system available. Unlike other systems that are designed around an open steel frame inside a molded plastic cabinet, the ETHOS features an 18/8 stainless steel cavity surrounded by a cabinet of solid 18/8 stainless steel, fitted with a heavy duty, spring mounted door for optimum operator safety and long operating lifetime. The door and cavity have a multi-layer PTFE plasma coating, applied at 350°C, with a 5 year warranty against corrosion. Unlike other systems, the user control electronics and user display have been moved out of the mainframe into a separate control module, protecting them from corrosion caused by acid vapor.
The new Ethos is constructed with a self-sealing, all stainless steel door, which is mounted on spring-loaded high impact steel bars on both sides of the mainframe. Although Milestone’s unique vent-and-reseal vessels and unmatched cavity volume means that a sudden over-pressurization of the cavity itself is extremely unlikely, should it occur, the self-sealing door will release pressure via its spring mounts and instantly reseal, protecting the operator. No other manufacturer offers a self-sealing door: other designs rely on simple latches housed in plastic to hold the door closed under normal operation.
With a redesigned cavity of over 70 liters, the Ethos is capable of accommodating larger rotors to improve productivity and throughput. Completely new rotors SK-15 and MAXI-44 provide high pressure and high throughput capabilities. The larger cavity is inherently much safer since a larger volume can better contain any gases escaping from vessels in the event of a sudden over-pressurization.
SafeVIEW, a high definition digital camera, is interfaced with the instrument terminal. It enables observation of the digestion while fully protected by the all-stainless steel door of the instrument. The terminal displays the video of the entire run in real time alongside the digestion parameters.
Additionally, the system employs a rotating diffuser that uniformly distributes microwaves throughout the cavity. As a result, samples are heated evenly, resulting in complete, reproducible sample digestions.
By employing both direct temperature control in a reference vessel, and the contactless IR temperature control, the Ethos plots the temperature in each vessel of the digestion run – in real time. This allows the analyst to confirm that each sample reached the target temperature and was held there for the time required by the digestion method. This is of particular importance when following U.S. EPA Methods. For example EPA 3052, used for the digestion of environmental samples, specifies that a temperature of 180° C +/- 5° C must be held for 10 minutes. Other systems display only the max. temperature each vessel reached – not the time the max. temperature was held for.
Additionally, contact-less pressure monitoring allows for control of all vessels simultaneously preventing any leaking or venting. These sensors ensure complete, safe, and reproducible, digestions without the loss of volatile elements.