CCT Chambers - Air Drying Mode - how it works
CCT Chamber - Air Drying Mode
This mode of operation is provided as standard on all models of Ascott CCT chamber. During this mode, air is drawn from the room in which the chamber is located, and may be heated before being blown into the chamber. This air displaces the air inside the chamber and 'drys' the chamber atmosphere by evaporating any moisture from the interior and dispersing it via the exhaust vent. The chamber can be used for air drying at a user adjustable temperature from ambient to +70°C/158°F.
The control system fitted to Ascott CCT chambers enables the user to program whether air drying is conducted alone, or in sequence with other climates, to form a cyclic corrosion test, for automatic execution by the chamber.
Air inlet & blower
Fresh air, at ambient temperature and humidity, is drawn from the immediate surroundings of the room in which the chamber is located, by a powerful centrifugal fan type blower. Two blowers are fitted to 2000L size chambers. These blowers deliver air to chamber interior via a heater, ball valve and air diffuser, described below.
An in-line electrical heater is provided to raise the temperature of the incoming ambient air from the blower - if required (determined by user adjustable set temperature), before delivering this air to the chamber. The heat generated by the blower heater is supplemented by the chamber heating mats (described below) in the air drying mode of operation, to give the chamber a user adjustable temperature range from ambient to +70°C/158°F.
An electrically operated ball valve automatically seals the blower/heater from the potentially corrosive atmosphere inside the chamber, whenever the blower is not running.
A carefully shaped air diffuser delivers the fresh air from the blower/heater and disperses it evenly throughout the chamber interior.
Chamber heating mats
Silicone rubber encapsulated electrical heating mats are strategically bonded to the outside surfaces of the bottom and sides of the inner working chamber. If required (determined by user adjustable set temperature), these heater mats operate in conjunction with the blower heater to raise the temperature of the chamber interior. In the air drying mode of operation, the heater mats and blower heater, operating together, give the chamber a user adjustable temperature range from ambient to +70°C/158°F.
Forming the centre-piece of the ergonomically designed control panel is a state of the art, touch-screen, Human Machine Interface (HMI). It is here that the user controls and monitors the various chamber functions. The HMI incorporates alpha-numeric text messaging and digital displays of chamber variables such as temperature, humidity and time . Also included is a useful trend logging facility. This generates a graphical display of set values for temperature & humidity, over a 72 hour time period, and compares this to the actual temperature and humidity achieved inside the chamber, over the same period.
All chamber control panels incorporate an emergency stop and other safety facilities.
The chamber canopy is effortlessly opened/closed using pneumatic cylinders, which are activated at the touch of a button on the control panel. An automatic purge facility is incorporated to minimise the risk of corrosive salt spray escaping into the laboratory when the chamber is opened.
Strategically located sensors, mounted inside the chamber and air saturator, monitor the climate continuously and convey this information to the Human Machine Interface (HMI), where it is displayed digitally at the control panel. Temperatures are monitored by PT100 precision temperature sensors and displayed to a resolution of 0.1°C. CCT chambers are also equipped with a special design of corrosion resistant humidity sensor. This measures the relative humidity electronically inside the chamber and displays this at the HMI as %RH to a resolution of 1%RH.
Test samples are accommodated within the chamber generally by placing on, or by suspending beneath, sample racks. A full set of sample racks are provided as standard with each new chamber (see chamber data sheets for quantity) in a choice of styles. Additional sample racks are available as optional accessories, if required, as is a reinforced false floor (ref; ACC19) for supporting large/heavy test samples directly on the chambers internal base.
This vents spent air from inside the chamber to atmosphere. The chamber should therefore ideally be located adjacent to an outside wall, and a hole made through the wall to accommodate the exhaust pipe. The end of this pipe should be directed away from persons and property, and be shielded from wind to prevent any disturbance to the conditions inside the chamber.
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